An integrated study of human and animal infectious disease in the Lake Victoria crescent small-holder crop-livestock production system, Kenya

Consumer preferences and willingness to pay for safe pork products in rural Kenya

Designing interventions to support the safe development of rapidly growing livestock value chains in sub-Saharan Africa requires a clear understanding of consumer demands. This study aimed to determine purchase patterns, consumers' preferences, and willingness to pay for safe pork attributes; specifically, the presence of a veterinary inspection stamp and the cleanliness of the butchery. A discrete choice experiment-based survey was used to investigate the purchasing behavior of 401 pork consumers: 253 buying raw pork for household consumption, and 148 buying cooked pork for out-of-home consumption. The study findings indicate that the average quantity of pork purchased by consumers was approximately 0.4 Kg per transaction, with the majority of consumers making several purchases per week. The average price per Kg of pork was KES 310 (Approx. 2.60 USD) at the time of the study. Data from the choice experiment showed that consumers were willing to pay a price premium of KES 245 (Approx. 2.1 USD) and KES 164 (Approx. 1.4 USD) per Kg for evidence of better veterinary meat inspection and higher butchery hygiene respectively; further, these were the two most important attributes they considered while making a pork purchase decision. These findings highlight the potential to leverage consumers' willingness to pay to improve the food safety within pork value chains in this context. Investing to increase consumer awareness on food safety issues should be considered to generate an effective market demand, especially in rural areas with relatively lower literacy levels.

Knowledge, perceptions, and practices around zoonotic diseases among actors in the livestock trade in the Lake Victoria crescent ecosystem in East Africa

Background

Zoonotic diseases such as anthrax, rabies, brucellosis, and Rift Valley fever pose a direct threat to health and undercut livelihoods in the communities in which they occur. A combination of anthropogenic and animal activities like migration and interaction with wildlife and their respective parasites and vectors drives the emergence and re-emergence of zoonotic diseases. Consequently, One Health interdisciplinary approaches that incorporate social scientists can provide key insights into complex local perceptions. The approach calls for collaboration between the human and animal health sectors, including the sharing of disease surveillance data necessary to alleviate disease impacts. Livestock traders interact closely with livestock, which puts them at elevated risk of infection and creates conditions by which they may spread zoonotic disease. It is thus essential to examine practices among actors involved in the livestock trade to understand the most appropriate ways to mitigate these risks.

Methods

A qualitative study was conducted among the actors in the livestock trade in Busia County on their knowledge and perceptions of zoonotic diseases and practices that may contribute to the spread, control, and prevention of zoonotic disease transmission. A thematic analysis framework was used to categorize and synthesize data from in-depth interviews (IDIs), key informant interviews (KIIs), and structured observations.

Results

Whereas participants could list livestock diseases, they could not identify which ones were zoonoses, demonstrating insufficient knowledge of zoonosis. They identify sick animals by checking for dropped ears, excess mucus production, diarrhea, bloody urinal discharge, and general animal activity levels. To prevent the spread of these diseases, they wash their animals, isolate sick animals from the rest of the stock, and vaccinate their animals. They seek help from animal health professionals for sick animals as part of curative practices. This shows that they perceive the diseases as serious and that they need to be attended to by professionals. The results also show that they perceive animals from outside the region to be more vulnerable to diseases compared to those from within. The actors in the livestock trade engage in practices like skinning dead animals before burying them; to them, this is a normal practice. Some also consume dead carcasses. These increase the risk of zoonotic disease transmission.

Conclusion

The actors involved in the livestock trade are critical in the prevention and elimination of zoonotic diseases; hence, they need to be involved when developing intervention programs and policies for animal health extension services. Training them as a continuum of animal health workers blends lay and professional knowledge, which, alongside their intense contact with large numbers of animals, becomes a critical disease surveillance tool. Increasing awareness of zoonoses by using multi-disciplinary teams with social scientists is urgently needed so that practices like skinning dead animals before disposing of them and consumption of dead carcasses can be minimized.

Epidemiology of intestinal helminthiasis with an emphasis on taeniasis in Chipata district of the Eastern province of Zambia

BACKGROUND

Intestinal helminth infections are among the most common infections worldwide and have a negative impact on the health, education, nutrition and economic development of affected populations. This study aimed to estimate the prevalence of intestinal helminthiasis, including T. solium taeniasis, using a large-scale community-based study in Chiparamba area of Chipata District in the Eastern province of Zambia.

METHODS/PRINCIPAL FINDINGS

A cross-sectional study was conducted between June 2019 and December 2022 in a rural community of 25 randomly selected villages known to be at risk for T. solium infection. Stool samples were examined for intestinal helminths using the formol-ether concentration technique and further tested for taeniasis by copro antigen-ELISA (copro Ag-ELISA). Descriptive statistical analyses were conducted, and associations between the disease prevalence of active infections and individual- and village-level variables were determined using the chi-square or Fisher's exact test. Predictors of an individual being positive for either taeniasis or other soil-transmitted helminths were determined using binary logistic regression. A total of 2762 stool samples were examined. One hundred ninety-five (7.1%) tested positive for at least one helminthic parasite on microscopy, with hookworm being the most frequent 84 (3.0%), followed by S. mansoni, 66 (2.4%). For taeniasis, 11 (0.4%) participants were positive for Taenia spp. microscopically, while 241 (8.7%) tested positive via copro Ag-ELISA. On bivariate analysis, male sex was significantly associated with the prevalence of intestinal parasites (p = 0.012) but not with that of taeniasis based on copro Ag-ELISA results. Village level differences were significant for infection with intestinal helminths as well as for taeniasis positivity on copro Ag-ELISA (p <0.001).

CONCLUSION

Intestinal helminths, including T. solium taeniasis, are prevalent in Chiparamba area of Chipata district in the eastern province of Zambia, supporting the clear need for further targeted public health interventions for surveillance and control.

Improved latrine coverage may reduce porcine cysticercosis: a comparative cross-sectional study, Busia County, Kenya 2021

Introduction

Smallholder pig farming is an important economic activity for many poor, rural communities in developing countries. Porcine cysticercosis is a growing public health risk in countries where pig rearing is popular. A sanitation-based intervention to reduce the prevalence of open defecation was completed in Busia County, Kenya in 2016. We capitalized on this third party intervention to evaluate its impact on porcine cysticercosis prevalence.

Methods

We conducted a comparative cross-sectional survey from August through to September 2021. Household selection was done using multistage sampling. Household questionnaire data on pig production, transmission, risk factors and awareness of porcine cysticercosis were collected from 251 households. Lingual palpation was used to test for cysticerci in 370 pigs while serum was tested for circulating antigen using Ag-ELISA. We compared results of our survey to an effective baseline, which was a near equivalent cross sectional survey conducted in 2012 before the third party sanitary intervention was established. The difference in prevalence was measured using Chi-square tests. Multivariable logistic regression analysis was used to identify risk factors for lingual cysts in pigs.

Results

The prevalence of palpable lingual cysts was estimated to be 3.8% (95% CI 2.3-6.3%) (14/370). This was 6% (95% CI 0.8-13.9%; p-value 0.0178) lower than the prevalence reported in the pre-implementation period of 9.7% (95% CI: 4.5-17.6%). Circulating antigen was detected in 2 samples (0.54%, 95% CI: 0.2-1.9). Latrine coverage was 86% (95% CI: 81-90%), which was 11% (95% CI: 4.8-16.8%; p < 0.001) higher than the pre-implementation period coverage of 75% (95% CI: 71-79%). There was reduced prevalence of lingual cysts in pigs from households that had a latrine (OR = 0.14; 95% CI: 0.05-0.43; p < 0.001) and where pigs were confined or tethered (OR = 0.27; 95% CI: 0.07-1.02; p = 0.053).

Conclusion

There was a reduction in the prevalence of porcine cysticercosis in Busia County over the study period from 2012 to 2021. This was not a trial design so we are unable to directly link the decline to a specific cause, but the data are consistent with previous research indicating that improved sanitation reduces porcine cysticercosis. Programs for controlling porcine cysticercosis should include a focus on sanitation in addition to other integrated One Health approaches.

Evidence of Histoplasma capsulatum seropositivity and exploration of risk factors for exposure in Busia county, western Kenya: Analysis of the PAZ dataset

BACKGROUND

Despite recognition of histoplasmosis as a disease of national public health concern in Kenya, the burden of Histoplasma capsulatum in the general population remains unknown. This study examined the human seroprevalence of anti-Histoplasma antibody and explored associations between seropositivity and demographic and environmental variables, in Busia county, western Kenya.

METHODOLOGY

Biobanked serum samples and associated data, from a previous cross-sectional survey, were examined. Latex agglutination tests to detect the presence of anti-Histoplasma antibody were performed on serum samples from 670 survey respondents, representing 178 households within 102 sub-locations. Potential epidemiologic risk factors for H. capsulatum exposure were explored using multi-level multivariable logistic regression analysis with household and sub-location included as random effects.

PRINCIPAL FINDINGS

The apparent sample seroprevalence of anti-Histoplasma antibody was 15.5% (n = 104/670, 95% Confidence Interval (CI) 12.9-18.5%). A multivariable logistic regression model identified increased odds of H. capsulatum seropositivity in respondents reporting rats within the household within the previous 12 months (OR = 2.99 90% CI 1.04-8.55, p = 0.04). Compared to respondents aged 25-34 years, the odds of seropositivity were higher in respondents aged 15-24 years (OR = 2.70 90% CI 1.04-6.97, p = 0.04).

CONCLUSIONS

The seroprevalence result provides a baseline for sample size approximations for future epidemiologic studies of the burden of H. capsulatum exposure in Busia county. The final model explored theoretically plausible risk factors for H. capsulatum exposure in the region. A number of factors may contribute to the complex epidemiological picture impacting H. capsulatum exposure status at the human-animal-environment interface in western Kenya. Focussed H. capsulatum research is warranted to determine the contextual significance of identified associations, and in representative sample populations.

Multi-Drug Resistant Staphylococcus aureus Carriage in Abattoir Workers in Busia, Kenya

Abattoir workers have been identified as high-risk for livestock-associated Staphylococcus aureus carriage. This study investigated S. aureus carriage in abattoir workers in Western Kenya. Nasal swabs were collected once from participants between February-November 2012. S. aureus was isolated using bacterial culture and antibiotic susceptibility testing performed using the VITEK 2 instrument and disc diffusion methods. Isolates underwent whole genome sequencing and Multi Locus Sequence Types were derived from these data. S. aureus (n = 126) was isolated from 118/737 (16.0%) participants. Carriage was higher in HIV-positive (24/89, 27.0%) than HIV−negative participants (94/648, 14.5%; p = 0.003). There were 23 sequence types (STs) identified, and half of the isolates were ST152 (34.1%) or ST8 (15.1%). Many isolates carried the Panton-Valentine leucocidin toxin gene (42.9%). Only three isolates were methicillin resistant S. aureus (MRSA) (3/126, 2.4%) and the prevalence of MRSA carriage was 0.4% (3/737). All MRSA were ST88. Isolates from HIV-positive participants (37.0%) were more frequently resistant to sulfamethoxazole/trimethoprim compared to isolates from HIV-negative participants (6.1%; p < 0.001). Similarly, trimethoprim resistance genes were more frequently detected in isolates from HIV-positive (81.5%) compared to HIV-negative participants (60.6%; p = 0.044). S. aureus in abattoir workers were representative of major sequence types in Africa, with a high proportion being toxigenic isolates. HIV-positive individuals were more frequently colonized by antimicrobial resistant S. aureus which may be explained by prophylactic antimicrobial use.

Zoonotic diseases risk perception and infection prevention and control practices among poultry farmers in the Buea Health District, Cameroon: A one health perspective

Background and Aim

Livestock are associated with pathogenic microbes and farm workers play a significant role in the transmission of zoonotic diseases (ZDs). Lack of awareness of exposure risk among farmers may influence their farm practices, thereby enhancing the spread of diseases on farms and to the community. This study was aimed at evaluating the knowledge, risk perception, and prevention and control practices of ZDs among poultry farmers to provide baseline data for establishing a "One Health" practical approach to reducing ZD transmission in poultry farms.

Materials and Methods

Using the exponential discriminative snowball technique, a community-based cross-sectional study involving poultry farmers was carried out in the Buea Health District from April to July 2021. Six feed-producing mills were used as focal points to identify and recruit farmers who were also referred to other farmers. Questionnaires were used to collect data related to participants' knowledge, risk perception, and prevention and control practices of ZDs. Descriptive analyses were performed for all variables while the chi-square test and logistic regression analysis were used to determine associations at 95% confidence level.

Results

In all, 183 poultry farms and 207 workers were enrolled in the study. Despite being aware that animal diseases can be transmitted to humans, most participants showed poor knowledge (54.6%), low-risk perception (51.7%), and poor prevention/control practices (54.1%) on ZDs. The majority did not consider coming in contact with birds' body fluid (blood) or apparently healthy birds to be a risk of infection. More participants with small farms (<500 birds) had low-risk perception of ZDs than those with larger farms (>1000 birds) (p = 0.03). Furthermore, most participants reported practicing hand washing but they neither used protective devices such as gloves and face masks, and >50% would not invite veterinary professionals to their farms. There was a significant association between risk perception and knowledge (p = 0.007; CI = 1.257-4.200) as well as between risk perception and prevention/control practice (p = 0.002; CI = 1.451-4.867).

Conclusion

Poultry farm workers in Buea had poor knowledge and perception of ZD risk and this might have contributed to their poor prevention/control practices on the farms. Enhanced informal education of poultry farmers through training workshops and seminars will improve their knowledge and skills on ZD transmission risk and prevention.

Molecular screening reveals non-uniform malaria transmission in western Kenya and absence of Rickettsia africae and selected arboviruses in hospital patients

Background

In sub-Saharan Africa, malaria is the common diagnosis for febrile illness and related clinical features, resulting in the under-diagnosis of other aetiologies, such as arboviruses and Rickettsia. While these may not be significant causes of mortality in malaria-endemic areas, they affect the daily life and performance of affected individuals. It is, therefore, important to have a clear picture of these other aetiologies to institute correct diagnoses at hospitals and improve patient outcomes.

Methods

Blood samples were collected from patients with fever and other clinical features associated with febrile illness at selected hospitals in the malaria-endemic counties of Busia, Bungoma, and Kakamega, and screened for Crimean-Congo haemorrhagic fever, Sindbis, dengue and chikungunya viruses, Rickettsia africae, and Plasmodium spp. using high-throughput real-time PCR techniques. A logistic regression was performed on the results to explore the effect of demographic and socio-economic independent variables on malaria infection.

Results

A total of 336 blood samples collected from hospital patients between January 2018 and February 2019 were screened, of which 17.6% (59/336) were positive for Plasmodium falciparum and 1.5% (5/336) for Plasmodium malariae. Two patients had dual P. falciparum/P. malariae infections. The most common clinical features reported by the patients who tested positive for malaria were fever and headache. None of the patients were positive for the arboviruses of interest or R. africae. Patients living in Busia (OR 5.2; 95% CI 2.46–11.79; p < 0.001) and Bungoma counties (OR 2.7; 95% CI 1.27–6.16; p = 0.013) had higher odds of being infected with malaria, compared to those living in Kakamega County.

Conclusions

The reported malaria prevalence is in line with previous studies. The absence of arboviral and R. africae cases in this study may have been due to the limited number of samples screened, low-level circulation of arboviruses during inter-epidemic periods, and/or the use of PCR alone as a detection method. Other sero-surveys confirming their circulation in the area indicate that further investigations are warranted.

Changing food systems and infectious disease risks in low-income and middle-income countries

The emergence of COVID-19 has drawn the attention of health researchers sharply back to the role that food systems can play in generating human disease burden. But emerging pandemic threats are just one dimension of the complex relationship between agriculture and infectious disease, which is evolving rapidly, particularly in low-income and middle-income countries (LMICs) that are undergoing rapid food system transformation. We examine this changing relationship through four current disease issues. The first is that greater investment in irrigation to improve national food security raises risks of vector-borne disease, which we illustrate with the case of malaria and rice in Africa. The second is that the intensification of livestock production in LMICs brings risks of zoonotic diseases like cysticercosis, which need to be managed as consumer demand grows. The third is that the nutritional benefits of increasing supply of fresh vegetables, fruit, and animal-sourced foods in markets in LMICs pose new food-borne disease risks, which might undermine supply. The fourth issue is that the potential human health risks of antimicrobial resistance from agriculture are intensified by changing livestock production. For each disease issue, we explore how food system transition is creating unintentional infectious disease risks, and what solutions might exist for these problems. We show that successfully addressing all of these challenges requires a coordinated approach between public health and agricultural sectors, recognising the costs and benefits of disease-reducing interventions to both, and seeking win-win solutions that are most likely to attract broad policy support and uptake by food systems.

Global variation in force-of-infection trends for human Taenia solium taeniasis/cysticercosis

Infection by Taenia solium poses a major burden across endemic countries. The World Health Organization (WHO) 2021–2030 Neglected Tropical Diseases roadmap has proposed that 30% of endemic countries achieve intensified T. solium control in hyperendemic areas by 2030. Understanding geographical variation in age-prevalence profiles and force-of-infection (FoI) estimates will inform intervention designs across settings. Human taeniasis (HTT) and human cysticercosis (HCC) age-prevalence data from 16 studies in Latin America, Africa, and Asia were extracted through a systematic review. Catalytic models, incorporating diagnostic performance uncertainty, were fitted to the data using Bayesian methods, to estimate rates of antibody (Ab)-seroconversion, infection acquisition and Ab-seroreversion or infection loss. HCC FoI and Ab-seroreversion rates were also estimated across 23 departments in Colombia from 28,100 individuals. Across settings, there was extensive variation in all-ages seroprevalence. Evidence for Ab-seroreversion or infection loss was found in most settings for both HTT and HCC and for HCC Ab-seroreversion in Colombia. The average duration until humans became Ab-seropositive/infected decreased as all-age (sero)prevalence increased. There was no clear relationship between the average duration humans remain Ab-seropositive and all-age seroprevalence. Marked geographical heterogeneity in T. solium transmission rates indicate the need for setting-specific intervention strategies to achieve the WHO goals.

Prevalence of Epilepsy, Human Cysticercosis, and Porcine Cysticercosis in Western Kenya

Cysticercosis is the leading cause of acquired epilepsy worldwide and has been shown to be highly prevalent in pig populations in western Kenya. We conducted a community-based door-to-door survey in a region of western Kenya with a high proportion of pig-keeping households. Persons with epilepsy (PWE) were determined using a screening questionnaire followed by a neurologist evaluation. Cysticercosis serum apDia antigen ELISAs and Western blot for LLGP and rT24h antigen were performed on all PWE and 2% of screen-negative patients. All PWE or people with positive apDia underwent contrast-enhanced brain computed tomography (CT). Of a sample of 810 village residents, 660 (81%) were present in the homestead, of whom 648 (98%) participated. Of these, 17 were confirmed to have lifetime epilepsy, an estimated crude prevalence of 2.6%. No humans with (N = 17) or without (N = 12) epilepsy had serological evidence of cysticercosis infection. Fourteen PWE and one individual with borderline positive apDia antigen ELISA underwent brain CT; none had radiographic findings consistent with neurocysticercosis. Nearly 30% of households kept pigs, with 69% always tethered in both wet and dry seasons. More than 8% (6/72) of pigs had palpable lingual cysts; these pigs all originated from homesteads with latrines, one-third of which were free-ranging at least some of the time. Epilepsy prevalence in our study was greater than the national prevalence, but we found no individuals with epilepsy attributable to cysticercosis. Additional studies are required to identify causes of epilepsy, human and porcine cysticercosis, the role of spatial clustering, and protective factors like host-pathogen immunity.

Exposure to multiple pathogens - serological evidence for Rift Valley fever virus, Coxiella burnetii, Bluetongue virus and Brucella spp. in cattle, sheep and goat in Mali

An important problem for livestock production in Mali is occurrence of several infectious diseases. A particular challenge for control of pathogens that affect different species, especially in a system with mixed herds with cattle, sheep and goats. Therefore, this study aimed to investigate co-exposure with Rift Valley fever virus (RVFV), Coxiella burnetii, Bluetongue virus (BTV) and Brucella spp. in different livestock species in mixed herds. With the exception of BTV these pathogens are also zoonotic. A retrospective assessment was carried out on a biobank of sera of cattle and small ruminants collected from Sikasso and Mopti regions. Nine hundred and twelve samples from cattle (n = 304), sheep (n = 318) and goat (n = 290) were screened. Serology tests were conducted using commercial kits as per the protocol of the manufacturers. Sero-prevalence for RVFV was 12.8% (Confidence Interval 95%: 9.3–17.1%); 4.7% (2.7–7.7%) and 3.1% (1.4–5.8%) in cattle, sheep and goat respectively. For Coxiella burnetii, the sero-prevalence was 55.3% (49.5–60.9%), 22.6% (18.2–27.6%), and 16.9% (12.8–21.7%); in cattle, sheep and goat respectively; and for BTV sero-prevalence was 88.8% (84.72–92.13%), 51.6% (45.9–57.2%), 56.2% (50.3–62.0%) in cattle, sheep in goat respectively. Brucella sp. had the lowest sero-prevalence and was only detected in cattle and sheep. Regional differences were observed with sero-prevalence of Coxiella burnetii in sheep and goat with BTV in goat being significantly higher in Sikasso than in Mopti (p<0.001). Evidence of exposure to two pathogens in the same animal was most common for the combination Coxiella burnetii and BTV in cattle (51.6%), followed by sheep (17.0%) and goat (15.5%). Considering the scarcity of disease occurrence and epidemiological data in most sub-saharan countries including Mali, this multi-pathogen survey provides important evidence that cattle, sheep and goat are exposed to pathogens that may negatively impact productivity and pose a risk for public health. The results from this study highlight the urgent need for a better understanding of pathogen diversity and their impact on human and animal health in order to minimize resulting risks. Given that some of the pathogens investigated here are zoonotic, establishment of One-Health surveillance system to monitor disease in animals and people is warranted. Therefore, intersectoral collaboration is recommended.

High prevalence of Rift Valley fever virus, Coxiella burnetii and Bluetongue virus were observed in cattle, sheep, and goats. We provided evidence that animals of the same herds have to cope with several pathogens. This study points out to need for important follow up studies to fill further knowledge gaps related to impacts of livestock diseases in Mali, especially zoonoses, and how to address the challenges.

Epidemiology of Porcine Cysticercosis in Eastern and Southern Africa: Systematic Review and Meta-Analysis

Taenia solium cysticercosis is the most common cause of acquired epilepsy in pig-raising and pork-consuming parts of Africa, Latin America, and Asia. This review aimed to systematically compile and synthesize data on the epidemiology of porcine cysticercosis in the Eastern and Southern Africa (ESA) region. Comprehensive searching strategies were employed to retrieve the studies published or reported between January 1,1997 and March 1, 2021, from Pub Med, Hinari, and Google Scholar databases and search platforms. The identified studies that met the inclusion criteria were then appraised for methodological quality. Finally, 44 studies obtained from nine countries were selected and included in this review. Relevant data were extracted using standardized templates for qualitative synthesis and meta-analysis. The overall pooled prevalence estimate of porcine cysticercosis in the ESA region was 17% (95% CI: 14-20%). The prevalence level between and within countries showed high variability. The pooled estimate showed high heterogeneity among the reports (the inverse variance index value (I2) of 98.99%, p < 0.05). The meta-analysis sub-grouped by the type of diagnostic test showed the pooled prevalence estimate of 27% (95% CI: 9-50) by carcass dissection; 23% (95% CI: 14-33) by Antibody-based immunodiagnostic techniques; 23% (95% CI: 18-29) by antigen detecting (Ag)-ELISA, 12% (95% CI: 7-18) by meat inspection, and 9% (95% CI: 7-11) by lingual examination. The meta-analysis sub-grouped by region showed a relatively higher pooled prevalence estimate for the Southern region 22% (95% CI: 15-30) compared to 13% (95% CI: 11-15) in the Eastern region. The highest country-based pooled prevalence was obtained from South Africa (33%, 95% CI: 20-48) and Zambia (22%, 95% CI: 16-29), whereas the lowest pooled prevalence was identified in Madagascar (5%, 95% CI: 4-5) and Rwanda (7%, 95% CI: 6-8). The lack of latrine, traditional pig husbandry practices, unprotected water sources, and increase in age were identified as significant risk factors for the occurrence of porcine cysticercosis in the pooled studies. The findings of this review will provide context-specific input to prioritize the possible intervention programs for T. solium control in the ESA region. More sensitive and specific test-based prevalence estimates, detailed risk factor investigations, and financial losses analysis are needed to establish feasible control strategies.

Systematic Review Registration

http://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42021238931.

The first study on seroprevalence and risk factors for zoonotic transmission of ovine and caprine brucellosis in the Province of Bam, Burkina Faso

Background and Aim:

Brucellosis is a bacterial disease notorious for its ability to infect a wide range of domestic and wildlife animals, as well as humans. This study aimed to determine the seroprevalence of ovine and caprine brucellosis and the associated risk factors in the Province of Bam in Burkina Faso.

Materials and Methods:

The individual serological status of 300 unvaccinated sheep and 300 unvaccinated goats was determined by Rose Bengal and indirect enzyme-linked immunosorbent assay (iELISA) serological tests used in parallel. The frequency of behaviors conferring risk of developing this zoonotic disease was determined through two epidemiological questionnaires, which identified known risk factors for the transmission of brucellosis between animals and humans.

Results:

Individual seroprevalence was estimated at 6.0% (18/300) in sheep and 4.3% (13/300) in goats. The “herd” prevalence of brucellosis was estimated at 60% in sheep while 40% in goats. Positivity in the iELISA serological test was significantly associated with age, sex, and husbandry system in sheep and goats.

Conclusion:

These results indicate that Brucella melitensis circulates in sheep and goat farms in the Province of Bam in Burkina Faso. As B. melitensis is highly pathogenic to humans, adequate measures must be taken to protect the population against this zoonotic disease.

Findings of a community screening programme for human cystic echinococcosis in a non-endemic area

Cystic Echinococcosis (CE) is a zoonosis caused by infection with the larval stages of the taeniid cestodes of the species complex Echinococcus granulosus sensu lato. It is prevalent among transhumant communities in East Africa, including those residing in northern Kenya. The movement of livestock from these regions of high incidence to areas of low incidence creates an indirect risk of disease spill-over to humans. To assess possible establishment of the CE life cycle outside known endemic regions, we used a portable ultrasound scanner to screen for the presence of human CE in Bungoma County of western Kenya, an area which imports substantial numbers of cattle for slaughter from neighbouring pastoralist regions. Eight sentinel sites were purposively selected based on their proximity to slaughterhouses handling animals introduced from pastoralist regions, and necessary permissions to conduct the study were sought. Regression analyses were conducted to identify risk factors associated with the presence of abdominal and cystic lesions (CL). In total, 1002 participants were screened; of these, 654 (65.3%) were female and the median age was 43. Farming (n = 403; 43.4%) was the most frequent occupation, followed by professional (i.e. on regular salary) (n = 215; 23.1%), and business (n = 207; 22.3%) categories. Sixty-seven participants (6.7%) had abnormal ultrasound findings, of these, 7 (1.1%) had simple liver cysts/CL, as per WHO classification. As such, their outcome was inconclusive and they were not put on treatment but advised to attend follow-up investigations in a referral health facility. Other abnormal findings included splenomegaly (n = 14), ovarian cysts (n = 14), uterine fibroids (n = 10), polycystic kidneys (n = 6), and benign prostatic hyperplasia (n = 6). Age was unconditionally associated with the presence of presumptive CL. These results contribute to CE baseline data while providing insights on the implementation of ultrasound diagnosis in the field, as recommended by the WHO for targeted control of echinococcosis by 2030.

Molecular prevalence and risk factors associated with tick-borne pathogens in cattle in western Kenya

Background

Tick-borne pathogens (TBPs) are of global importance, especially in sub-Saharan Africa where they represent a major constraint to livestock production. Their association with human disease is also increasingly recognized, signalling their zoonotic importance. It is therefore crucial to investigate TBPs prevalence in livestock populations and the factors associated with their presence. We set out to identify TBPs present in cattle and to determine associated risk factors in western Kenya, where smallholder livestock production is important for subsistence and market-driven income.

Results

Tick-borne pathogen infections in blood samples collected from cattle at livestock markets and slaughterhouses between May 2017 and January 2019 were identified by high-resolution melting analysis and sequencing of PCR products of genus-specific primers. Of the 422 cattle sampled, 30.1% (127/422) were infected with at least one TBP, while 8.8% (37/422) had dual infections. Anaplasma spp. (19.7%) were the most prevalent, followed by Theileria (12.3%), Ehrlichia (6.6%), and Babesia (0.2%) spp. Sequence analysis of the TBPs revealed them to be Anaplasma platys-like organisms (13.5%), Theileria velifera (7.4%), Anaplasma marginale (4.9%), Theileria mutans (3.1%), Theileria parva (1.6%), and Babesia bigemina (0.2%). Ehrlichia ruminantium, Rickettsia spp., and arboviruses were not detected. Exotic breeds of cattle were more likely to be infected with A. marginale compared to local breeds (OR: 7.99, 95% CI: 3.04–22.02, p <  0.001). Presence of ticks was a significant predictor for Anaplasma spp. (OR: 2.18, 95% CI: 1.32–3.69, p = 0.003) and Ehrlichia spp. (OR: 2.79, 95% CI: 1.22–7.23, p = 0.022) infection. Cattle sampled at slaughterhouses were more likely to be positive for Anaplasma spp. (OR: 1.64, 95% CI: 1.01–2.70, p = 0.048) and A. marginale (OR: 3.84, 95% CI: 1.43–12.21, p = 0.012), compared to those sampled at livestock markets.

Conclusion

This study reports TBP prevalence and associated risk factors in western Kenya, factors which are key to informing surveillance and control measures.

A Cross-Sectional Survey of the Knowledge, Attitudes, and Practices of Antimicrobial Users and Providers in an Area of High-Density Livestock-Human Population in Western Kenya

Background: Antimicrobial resistance (AMR) is one of the most important global health crises in recent times and is driven primarily by antimicrobial consumption. In East Africa, there is a paucity of data regarding the knowledge, attitudes, and practices (KAP) related to antimicrobial use (AMU). We investigate the ways in which antimicrobial users in the veterinary sector accessed veterinary antimicrobials, and common behaviors of veterinary antimicrobial users and prescribers associated with AMU and AMR.

Methods: In total, 70 farmers, staff at 49 agricultural-veterinary antimicrobial shops (agrovet staff) and 28 veterinary animal healthcare workers or veterinary surgeons (veterinary professionals) were interviewed in Busia county, western Kenya in 2016 using a standard questionnaire as a framework for structured interviews. Data recorded included participant demographics, level of education, access to and sources of veterinary antimicrobials, prescribing patterns, and knowledge of AMR and antimicrobial withdrawal periods.

Results: The majority of antimicrobials were accessed through informal means, purchased from agroveterinary shops; more than half of staff did not hold nationally mandated qualifications to advise on or sell veterinary antimicrobials. Approximately 40% of veterinary antimicrobials were sold without a prescription and it was noted that both price and customer preference were important factors when selling antimicrobials in almost all agrovet shops. Knowledge of the dangers associated with AMR and AMU were mostly superficial. Treatment failure occurred often, and there was a lack of differentiation between AMR and simply treatment failure.

Conclusion: In this study area in East Africa with high-density human and livestock populations, AMU was primarily for maintenance of livestock health. These findings have highlighted several aspects surrounding inappropriate access to antimicrobials, and as such require attention from policy makers concerned with AMR in both livestock and human medicine sectors. Improving prescribing practices and ensuring a minimum level of general education and awareness of prescribers, as well as expanding the role of agrovet staff in antimicrobial stewardship programmes, may help begin to mitigate the maintenance and transmission of AMR, particularly amongst livestock.

Prevalence and risk factors for exposure to Toxoplasma gondii in slaughterhouse workers in western Kenya

Background

Toxoplasma gondii is a zoonotic protozoan parasite infecting warm-blooded animals. Infection in people can occur through ingestion of oocysts passed in the faeces of the definitive hosts; ingestion of bradyzoites in the tissue of infected intermediate hosts; or exposure to tachyzoites in raw milk and eggs. Slaughterhouse workers are considered a high-risk group for T. gondii exposure because of their contact with raw meat, although a positive relationship between handling raw meat and T. gondii seropositivity has not been demonstrated in all studies. This study aimed to determine the seroprevalence of antibodies to T. gondii in slaughterhouse workers in Kenya and identify risk factors associated with seropositivity.

Methods

A survey of slaughterhouse workers was conducted in 142 slaughter facilities in the study area. Information regarding demographics, contact with livestock, meat consumption, and practices in the slaughterhouse was collected using structured questionnaires. Commercial ELISAs were used to detect IgM and IgG antibodies against T. gondii and a multi-level logistic regression model was used to identify potential risk factors for seropositivity in slaughterhouse workers.

Results

The apparent prevalence of antibodies to T. gondii was 84.0% (95% Confidence Interval (CI) 81.2–86.5%) for IgG and 2.2% (95% CI 1.3–3.5%) for IgM antibodies. All IgM positive individuals were IgG positive. Risk factors for exposure to T. gondii were: increasing age (Odds Ratio (OR) 1.03; 95% CI 1.01–1.05); owning poultry (OR 2.00; 95% CI 1.11–3.62); and consuming animal blood (OR 1.92; 95% CI 1.21–3.03).

Conclusions

The seroprevalence of antibodies to T. gondii was very high in this population and considerably higher than published values in the general population. Risk factors included age, owning poultry and drinking animal blood which were consistent with previous reports but none were specifically associated with working in the slaughterhouse. In this instance slaughterhouse workers may represent a useful sentinel for the general population where the level of exposure is also likely to be high and may signify an unidentified public health risk to vulnerable groups such as pregnant women. A detailed understanding of the epidemiology of infection is required, which should include an assessment of incidence, mortality, and burden since T. gondii infection is likely to have life-long sequelae.

Evidence of exposure to C. burnetii among slaughterhouse workers in western Kenya

Q fever, caused by C. burnetii, has been reported in slaughterhouse workers worldwide. The most reported risk factor for seropositivity is the workers' role in the slaughterhouse. This study examined the seroprevalence and risk factors for antibodies to C. burnetii in slaughterhouse workers in western Kenya to fill a data gap relating to this emerging disease in East Africa.

Individuals were recruited from all consenting slaughterhouses in the study area between February and November 2012. Information was collected from participating workers regarding demographic data, animals slaughtered and role in the slaughterhouse. Sera samples were screened for antibodies to C. burnetii using a commercial ELISA and risk factors associated with seropositivity were identified using multi-level logistic regression analysis.

Slaughterhouse workers (n = 566) were recruited from 84 ruminant slaughterhouses in western Kenya. The seroprevalence of antibodies to C. burnetii was 37.1% (95% Confidence Interval (CI) 33.2–41.2%). The risk factors identified for C. burnetii seropositivity included: male workers compared to female workers, odds ratio (OR) 5.40 (95% CI 1.38–21.22); slaughtering cattle and small ruminants compared to those who only slaughtered cattle, OR 1.52 (95% CI 1.06–2.19). In addition, specific roles in the slaughterhouse were associated with increased odds of being seropositive, including cleaning the slaughterhouse, OR 3.98 (95% CI 1.39–11.43); cleaning the intestines, OR 3.24 (95% CI 1.36–7.73); and flaying the carcass OR 2.63 (95% CI 1.46–4.75) compared to being the slaughterman or foreman.

We identified that slaughterhouse workers have a higher seroprevalence of antibodies to C. burnetii compared to published values in the general population from the same area. Slaughterhouse workers therefore represent an occupational risk group in this East African setting. Workers with increased contact with the viscera and fluids are at higher risk for exposure to C. burnetii. Education of workers may reduce transmission, but an alternative approach may be to consider the benefits of vaccination in high-risk groups.

Epidemiology of Pig Tuberculosis in Argentina

Bovine tuberculosis (bTB) is a disease caused mainly by the Mycobacterium bovis and that is endemic to livestock populations in most Latin American countries. Traditionally, bTB control programs are costly and targeted to cattle, largely disregarding other species such as swine and wildlife. According to official services, in Argentina disease prevalence in pigs is comparable to that observed in cattle, suggesting the need for efficient control programs to manage the disease in both species. Additionally, extensive farming systems, which are commonly practiced in Argentina, allow the interaction between livestock and wildlife such as wild boar (Sus scrofa), which is considered a natural host of the disease. Here, we evaluated the bTB pigs- cattle interface, studying the dynamics of M. bovis isolates in the pig population and identifying farm-level epidemiological variables associated with the disease confirmation at slaughterhouses. Additionally, to assess the potential multi-host systems in the transmission of bTB, the molecular characterization of wild boar mycobacterial strains was included in the study, as this interaction has not been previously evaluated in this region. Multivariable logistic regression models were used to assess the association between farm-level epidemiological variables (location, farm size, and co-existence with cattle and goats) and bTB confirmation in pig tuberculosis-like lesions samples. Results showed that when cattle were present, the odds of bTB in pigs decreased 0.3 or 0.6% for every additional sow when cattle were present or absent in the farm, respectively. Pigs shared 60% (18/30) of the genotypes with cattle and wild boar, suggesting transmission at the interface between pigs and cattle and highlighting the potential role of wild boar in bTB maintenance. These results provide novel information about the molecular diversity of M. bovis strains in pigs in Argentina and proposes the potential relevance of a multi-host system in the epidemiology of bTB in the region. The statistical models presented here may be used in the design of a low cost, abattoir-based surveillance program for bTB in the pig industry in Argentina, with potential extension to other settings with similar epidemiological conditions.

The epidemiology of bacterial zoonoses in pastoral and dairy cattle in Cameroon, Central Africa

Previous work identified that bacterial zoonoses (Brucella species, Coxiella burnetii and Leptospira hardjo) were present in Cameroonian pastoral cattle. To assess the characteristics of this zoonotic risk, we analyse seroprevalence of each pathogen and the associated management, herd and environmental factors in Cameroonian pastoral and dairy cattle. Cross-sectional samples included pastoralist herds in the Northwest Region (NWR n = 750) and Vina Division (VD n = 748) and small holder dairy herds in the NWR (n = 60). Exposure to Brucella spp., C. burnetii and L. hardjo were screened for using commercial ELISAs and population adjusted estimates made. In addition, individual, herd and ecological metadata were collected and used to identify risk factors associated with animal-level seropositivity. In the pastoral cattle, seroprevalence to Brucella spp. was relatively low but was higher in the NWR (4.2%, CI: 2.5%-7.0%) than the VD (1.1%: CI 0.5%-2.4%), while L. hardjo seroprevalence was much higher though similar in the NWR (30.7%, CI 26.3%-35.5%) and VD (35.9%, CI 31.3%-40.7%). No differences were noted in C. burnetii seroprevalence between the two study sites (NWR: 14.6%, CI 11.8%-18.0%. VD: 12.4%, 9.6%-15.9%). Compared to pastoral, dairy cattle had lower seroprevalences for L. hardjo (1.7%, CI: 0.0%-4.9%), C. burnetii (0.0%, CI 0.0%-6.0%) but similar for Brucella spp. (5.0%, CI 0.0%-10.6%). Increased odds of Brucella spp. seropositivity were associated with owning sheep or rearing sheep and fencing cattle in at night. Adult cattle had increased odds of being seropositive for both C. burnetii and L. hardjo. Additionally, exposure to C. burnetii was associated with local ecological conditions and L. hardjo was negatively associated with cattle undertaking transhumance. This work highlights that exposure to these 3 important production diseases and occupational zoonoses are widespread in Cameroonian cattle. Further work is required to understand transmission dynamics between humans and livestock to inform implementation of effective control measures.

Cross-Sectoral Zoonotic Disease Surveillance in Western Kenya: Identifying Drivers and Barriers Within a Resource Constrained Setting

Background: Collaboration between the human and animal health sectors, including the sharing of disease surveillance data, has the potential to improve public health outcomes through the rapid detection of zoonotic disease events prior to widespread transmission in humans. Kenya has been at the forefront of embracing a collaborative approach in Africa with the inception of the Zoonotic Disease Unit in 2011. Joint outbreak responses have been coordinated at the national level, yet little is currently documented on cross-sectoral collaboration at the sub-national level.

Methods: Key informant interviews were conducted with 28 disease surveillance officers from the human and animal health sectors in three counties in western Kenya. An inductive process of thematic analysis was used to identify themes relating to barriers and drivers for cross-sectoral collaboration.

Results: The study identified four interlinking themes related to drivers and barriers for cross-sectoral collaboration. To drive collaboration at the sub-national level there needs to be a clear identification of “common objectives,” as currently exemplified by the response to suspected rabies and anthrax cases and routine meat hygiene activities. The action of collaboration, be it integrated responses to outbreaks or communication and data sharing, require “operational structures” to facilitate them, including the formalisation of reporting lines, supporting legislation and the physical infrastructure, from lab equipment to mobile phones, to facilitate the activities. These structures in turn require “appropriate resources” to support them, which will be allocated based on the “political will” of those who control the resources.

Conclusions: Ongoing collaborations between human and animal disease surveillance officers at the sub-national level were identified, driven by common objectives such as routine meat hygiene and response to suspected rabies and anthrax cases. In these areas a suitable operational structure is present, including a supportive legislative framework and clearly designated roles for officers within both sectors. There was support from disease surveillance officers to increase their collaboration, communication and data sharing across sectors, yet this is currently hindered by the lack of these formal operational structures and poor allocation of resources to disease surveillance. It was acknowledged that improving this resource allocation will require political will at the sub-national, national and international levels.

Brucellosis: Prevalence with reference to East African community countries - A rapid review

Brucellosis is a zoonotic disease which is endemic to certain regions of the world including Sub-Saharan Africa. The aim of this article is to provide a recent and rapid review on brucellosis prevalence in East African Community (EAC) countries. Literature was obtained using Google Scholar search engine and screened for relevancy and fulfilment of criteria to 1, 17, 4, 4, 30 and 29 articles retained for brucellosis prevalence in Burundi, Kenya, Rwanda, South Sudan, Tanzania and Uganda. Recent literature (published in the last decade 2010 to 2019) was considered for prevalence results in this review. In EAC, livestock had an animal-level prevalence of 0.2% to 43.8%, 0.0% to 20.0% and 0.0% to 13.8% for cattle, goats and sheep respectively. In humans, the prevalence varied mostly between 0.0% and 35.8%. In conclusion, brucellosis is quite prevalent in the region. The reported prevalence calls for plans or more efforts from individual member countries and from EAC, as a region, to control brucellosis.

Who let the dogs out? Exploring the spatial ecology of free-roaming domestic dogs in western Kenya

The spatial ecology of free-roaming dogs determines their role in the transmission of zoonoses. This study describes the geographic range of and identifies sites frequently visited by free-roaming domestic dogs in western Kenya. Eight sites in Busia county, western Kenya, were selected. At each site, ten dog-keeping households were recruited, a questionnaire was administered, and a GPS logger was fixed around the neck of one dog in each household. Loggers were programmed to capture the dog's position every minute, for five consecutive days. Individual summaries of GPS recordings were produced, and the daily distance traveled was calculated. 50% and 95% utilization distribution isopleths were produced, and the area within these isopleths was extracted to estimate the size of the core and extended Home Ranges (HRs), respectively. Linear regression analyses were performed to identify factors associated with the movement parameters. The centroid points of the 10, 50, and 90% isopleths were reproduced, and the corresponding sites identified on the ground. Seventy-three dogs were included in the final analyses. The median daily distance traveled was 13.5km, while the median core and extended HRs were 0.4 and 9.3 ha, respectively. Older dogs had a larger extended HR and traveled more daily, while the effect of sex on dog movement depended on their neutering status. Dogs spent most of their time at their household; other frequently visited sites included other household compounds, fields, and rubbish dumps. One of the centroids corresponded to a field located across the international Kenya-Uganda border, emphasizing the fluidity across the border in this ecosystem. Multiple dogs visited the same location, highlighting the heterogeneous contact networks between dogs, and between dogs and people. The field data presented are of value both in understanding domestic dog ecology and resource utilization, and in contextualizing infectious and parasitic disease transmission models.

A Systematic Scoping Review of the Impacts of Community Food Production Initiatives in Kenya, Cameroon, and South Africa

BACKGROUND

Even before the COVID-19 pandemic, one in two people in Africa were food insecure. The burden of malnutrition remains high (e.g. childhood stunting, anaemia in women of reproductive age) or are increasing (e.g. overweight and obesity). A range of coordinated actions are required to improve this situation, including increasing local food production and consumption. The aim of this review was to provide a systematic and comprehensive overview of recently published research into the health, social, economic, and environmental impacts of community food production initiatives (CFPIs) in Kenya, Cameroon and South Africa.

METHODS

We searched eight electronic databases covering health, social, environmental, economic and agricultural sciences. Primary research studies published from 1 January 2014 to 31 December 2018 were considered. Data on geographic location, study design, type of CFPI and the impacts assessed were abstracted from eligible articles.

FINDINGS

We identified 4828 articles, 260 of which required full-text review and 118 met our eligibility criteria. Most research was conducted in Kenya (53.4%) and South Africa (38.1%). The categories of CFPIs studied were (in order of decreasing frequency): crop farming, livestock farming, unspecified farming, fisheries, home / school gardens, urban agriculture, and agroforestry. The largest number of studies were on the economic and environmental impacts of CFPIs, followed by their health and social impacts. The health impacts investigated included food security, nutrition status and dietary intake. One study investigated the potential impact of CFPIs on non-communicable diseases. Over 60% of studies investigated a single category of impact. Not one of the studies explicitly used a theoretical framework to guide its design or interpretation.

CONCLUSIONS

Our findings on research studies of CFPIs suggest the need for a greater focus on interdisciplinary research in order to improve understanding of the relationships between their health, environmental, economic, and social impacts. Greater use of explicit theoretical frameworks could assist in research design and interpretation, helping to ensure its relevance to informing coordinated intersectoral interventions and policy initiatives.

Novel transdisciplinary methodology for cross-sectional analysis of snakebite epidemiology at national scale

Background

Worldwide, it is estimated that snakes bite 4.5–5.4 million people annually, 2.7 million of which are envenomed, and 81,000–138,000 die. The World Health Organization reported these estimates and recognized the scarcity of large-scale, community-based, epidemiological data. In this context, we developed the “Snake-Byte” project that aims at (i) quantifying and mapping the impact of snakebite on human and animal health, and on livelihoods, (ii) developing predictive models for medical, ecological and economic indicators, and (iii) analyzing geographic accessibility to healthcare. This paper exclusively describes the methodology we developed to collect large-scale primary data on snakebite in humans and animals in two hyper-endemic countries, Cameroon and Nepal.

Methodology/Principal findings

We compared available methods on snakebite epidemiology and on multi-cluster survey development. Then, in line with those findings, we developed an original study methodology based on a multi-cluster random survey, enhanced by geospatial, One Health, and health economics components. Using a minimum hypothesized snakebite national incidence of 100/100,000/year and optimizing design effect, confidence level, and non-response margin, we calculated a sample of 61,000 people per country. This represented 11,700 households in Cameroon and 13,800 in Nepal. The random selection with probability proportional to size generated 250 clusters from all Cameroonian regions and all Nepalese Terai districts. Our household selection methodology combined spatial randomization and selection via high-resolution satellite images. After ethical approval in Switerland (CCER), Nepal (BPKIHS), and Cameroon (CNERSH), and informed written consent, our e-questionnaires included geolocated baseline demographic and socio-economic characteristics, snakebite clinical features and outcomes, healthcare expenditure, animal ownership, animal outcomes, snake identification, and service accessibility.

Conclusions/Significance

This novel transdisciplinary survey methodology was subsequently used to collect countrywide snakebite envenoming data in Nepal and Cameroon. District-level incidence data should help health authorities to channel antivenom and healthcare allocation. This methodology, or parts thereof, could be easily adapted to other countries and to other Neglected Tropical Diseases.

Snakebite envenoming was recently classified as a priority neglected tropical disease by the World Health Organization. Up to five million people are bitten, more than a million envenomed, and around 100,000 victims die, mainly in rural and remote areas of low- and middle-income countries. Snakebite envenoming not only affects victims acutely, but it can also cause long-term disability, disfiguring scars, and heavy economic burden due to treatment costs and inability to work. Previous studies have analyzed snakebite clinical, epidemiological, or socio-economic impacts independently, and little has been done to assess the impact of snakebite in animals and on the livelihoods of the communities that depend upon them.

We present an innovative, holistic, national-scale methodology that includes epidemiology, One Health, economic, and geographic information science approaches into one multi-cluster household survey. We randomly selected 250 sub-district areas from all Cameroonian regions and all Nepali Terai districts, which represented more than 61,000 participants in each country. This methodology could be adapted and implemented in other countries affected by snakebite.

Hospital-based evidence on cost-effectiveness of brucellosis diagnostic tests and treatment in Kenyan hospitals

Hospitals in Kenya continue to use the Febrile Antigen Brucella Agglutination Test (FBAT) to diagnose brucellosis, despite reports showing its inadequacy. This study generated hospital-based evidence on the performance and cost-effectiveness of the FBAT, compared to the Rose Bengal Test (RBT).Twelve hospitals in western Kenya stored patient serum samples that were tested for brucellosis using the FBAT, and these were later re-tested using the RBT. Data on the running time and cost of the FBAT, and the treatment prescribed for brucellosis, were collected. The cost-effectiveness of the two tests, defined as the cost in US Dollars ($) per Disability Adjusted Life Year (DALY) averted, was determined, and a basic sensitivity analysis was run to identify the most influential parameters. Over a 6-month period, 180 patient serum samples that were tested with FBAT at the hospitals were later re-tested with RBT at the field laboratory. Of these 24 (13.3%) and 3 (1.7%) tested positive with FBAT and RBT, respectively. The agreement between the FBAT and RBT was slight (Kappa = 0.12). Treatment prescribed following FBAT positivity varied between hospitals, and only one hospital prescribed a standardized therapy regimen. The mean $/DALY averted when using the FBAT and RBT were $2,065 (95% CI $481-$6,736) and $304 (95% CI $126-$604), respectively. Brucellosis prevalence was the most influential parameter in the cost-effectiveness of both tests. Extrapolation to the national level suggested that an estimated $338,891 (95% CI $47,000-$1,149,000) per year is currently spent unnecessarily treating those falsely testing positive by FBAT. These findings highlight the potential for misdiagnosis using the FBAT. Furthermore, the RBT is cost-effective, and could be considered as the mainstay screening test for human brucellosis in this setting. Lastly, the treatment regimens must be harmonized to ensure the appropriate use of antibiotics for treatment.

Brucellosis is the most common bacterial zoonosis globally, with a higher burden in low-resource settings. In humans, the disease manifests itself with non-specific clinical signs, and current international guidelines recommend the use of two serological diagnostic tests to make a confirmatory diagnosis. Many hospitals in Kenya and some neighbouring countries have been using the Febrile Antigen Brucella Agglutination Test (FBAT) for diagnosis, despite reports showing its poor performance. In this study we compared the diagnostic performance and cost-effectiveness of the FBAT with that of the Rose Bengal Test (RBT), a serological assay recommended by international guidelines. Our results showed that, compared to the RBT, the FBAT incorrectly diagnosed a number of patients. This is of concern as it leads to unnecessary antibiotic treatments, increasing the economic burden of the disease and exacerbating the risk of antibiotic resistance. We also highlight the discrepancies in brucellosis treatment regimens currently being prescribed by various hospitals. Finally, we showed that the RBT is a more cost-effective diagnostic test. Our recommendation, therefore, is for the RBT to be considered as the mainstay diagnostic test for human brucellosis in all Kenyan hospitals, and for the harmonization of treatment guidelines.

Tick-borne pathogens, including Crimean-Congo haemorrhagic fever virus, at livestock markets and slaughterhouses in western Kenya

Vectors of emerging infectious diseases have expanded their distributional ranges in recent decades due to increased global travel, trade connectivity and climate change. Transboundary range shifts, arising from the continuous movement of humans and livestock across borders, are of particular disease control concern. Several tick-borne diseases are known to circulate between eastern Uganda and the western counties of Kenya, with one fatal case of Crimean-Congo haemorrhagic fever (CCHF) reported in 2000 in western Kenya. Recent reports of CCHF in Uganda have highlighted the risk of cross-border disease translocation and the importance of establishing inter-epidemic, early warning systems to detect possible outbreaks. We therefore carried out surveillance of tick-borne zoonotic pathogens at livestock markets and slaughterhouses in three counties of western Kenya that neighbour Uganda. Ticks and other ectoparasites were collected from livestock and identified using morphological keys. The two most frequently sampled tick species were Rhipicephalus decoloratus (35%) and Amblyomma variegatum (30%); Ctenocephalides felis fleas and Haematopinus suis lice were also present. In total, 486 ticks, lice and fleas were screened for pathogen presence using established molecular workflows incorporating high-resolution melting analysis and identified through sequencing of PCR products. We detected CCHF virus in Rh. decoloratus and Rhipicephalus sp. cattle ticks, and 82 of 96 pools of Am. variegatum were positive for Rickettsia africae. Apicomplexan protozoa and bacteria of veterinary importance, such as Theileria parva, Babesia bigemina and Anaplasma marginale, were primarily detected in rhipicephaline ticks. Our findings show the presence of several pathogens of public health and veterinary importance in ticks from livestock at livestock markets and slaughterhouses in western Kenya. Confirmation of CCHF virus, a Nairovirus that causes haemorrhagic fever with a high case fatality rate in humans, highlights the risk of under-diagnosed zoonotic diseases and calls for continuous surveillance and the development of preventative measures.

A retrospective sero-epidemiological survey of bovine brucellosis on commercial and communal farming systems in Namibia from 2004 to 2018

Cattle production is the major livestock production activity and the mainstay of Namibia's economy. Sustained beef exports are contingent on a sound sanitary environment where diseases such as brucellosis are under control. In this retrospective study, 49,718 bovine brucellosis testing results from 2004 to 2018 were analyzed to determine the proportion of sero-positive cattle and herds, and the spatial distribution of positive reactors from commercial and communal areas. In total, 244 positive reactors were identified based on the Rose Bengal Test (RBT) and the Complement Fixation Test (CFT) in series, giving an overall proportion of infected animals of 0.49% (244/49,718; 95% CI, 0.43-0.56%) and an overall proportion of infected herds of 9.26% (78/842; 95% CI, 7.49-11.41%). There was a higher proportion of sero-positive communal herds (33.09%) and cattle (10.27%) than commercial herds (4.67%) and cattle (0.24%; p < 0.05). Annually, the proportion of positive reactors was 0-1.37% in the commercial area and 0-52.38% in the communal areas, with a clear decline in positive reactors in the communal areas. Within the commercial sector, the proportion of positive reactor dairy, beef, and export cattle was 0.19% (51/27,067; 95% CI, 0.14-0.25%), 0.30% (48/16,098; 95% CI, 0.22-0.40%), and 0.33% (16/4811; 95% CI, 0.20-0.54%), respectively. Abortions were found to be the major reason for Brucella testing in the communal areas. About 12.65% (96/759) of abortion-linked sera tested positive in the communal areas, but none were positive in beef or dairy cattle. Widespread vaccination of cattle and robust planned surveillance is recommended to reduce the incidence of the disease, its associated production losses and public health risk.

Prevalence and genotyping of Echinococcus granulosus sensu lato from livestock in north-eastern Kenya

Cystic echinococcosis (CE) is a zoonotic disease of cosmopolitan distribution and caused by the larval stage of the dog tapeworm, Echinococcus granulosus sensu lato (s.l.). CE occurs in the wider African continent and in Kenya, notably in the Maasailand and Turkana regions; however, recent studies demonstrate its presence in other parts of Kenya. This study determined the occurrence of CE in livestock (camels, goats, sheep and cattle) in Isiolo, Garissa and Wajir counties, and characterized the species of E. granulosus s.l. present. An abattoir survey was used to determine the presence of CE in various organs in livestock. Polymerase chain reaction-restriction fragment length polymorphism and sequencing of the mitochondrial NADH dehydrogenase subunit 1 gene was used for genotyping. A total of 1368 carcasses from 687 goats, 234 camels, 329 sheep and 118 cattle were inspected for the presence of hydatid cysts. The overall proportion of infections was 29.1% in camels, 14.4% in cattle, 9.9% in goats and 8.2% in sheep. The liver was the most infected organ, while only the lung of camels harboured fertile cysts. Of the 139 cysts genotyped, 111 (79.9%) belonged to Echinococcus canadensis (G6/7) and 20 (14.4%) to E. granulosus sensu stricto. One and two cysts were identified as Taenia saginata and unknown Taenia species, respectively. There was a significant association between county of origin and species of the animal with occurrence of CE. This study reports, for the first time, the characterization of Echinococcus species in livestock from Garissa and Wajir counties, and the current situation in Isiolo county. The fertility of cysts in camels and frequency of E. canadensis (G6/7) in all livestock species indicate that camels play an important role in the maintenance of CE in the north-eastern counties of Kenya.

Force-of-infection of Taenia solium porcine cysticercosis: a modelling analysis to assess global incidence and prevalence trends

The World Health Organization (WHO) called, in 2012, for a validated strategy towards Taenia solium taeniasis/cysticercosis control and elimination. Estimating pig force-of-infection (FoI, the average rate at which susceptible pigs become infected) across geographical settings will help understand local epidemiology and inform effective intervention design. Porcine cysticercosis (PCC) age-prevalence data (from 15 studies in Latin America, Africa and Asia) were identified through systematic review. Catalytic models were fitted to the data using Bayesian methods, incorporating uncertainty in diagnostic performance, to estimate rates of antibody seroconversion, viable metacestode acquisition, and seroreversion/infection loss. There was evidence of antibody seroreversion across 5 studies, and of infection loss in 6 studies measured by antigen or necropsy, indicating transient serological responses and natural resolution of infection. Concerted efforts should be made to collect robust data using improved diagnostics to better understand geographical heterogeneities in T. solium transmission to support post-2020 WHO targets.

Spatial Distribution of Trypanosomes in Cattle From Western Kenya

African Animal Trypanosomiasis (AAT) is a tsetse-transmitted protozoan disease endemic in “the tsetse belt” of Africa. Past studies investigating the epidemiology of the disease rarely focused on spatial distribution when reporting the prevalence. The challenge of understanding the spatial epidemiology of the disease is further confounded by low-sensitive parasitological techniques used in field investigations. This study aimed to identify trypanosome species in cattle and their spatial distribution in western Kenya. Low-sensitive microscopic analysis and highly-sensitive polymerase chain reaction (PCR) techniques were also compared to better understand the epidemiology of Trypanosoma infections by use of the geographical information system (GIS). Blood samples from 888 cattle, collected between August 2010 and July 2012, were examined for Trypanosoma parasites by light microscopy and PCR. The spatial distribution of Trypanosoma positive cases by species were mapped and overlaid on the map for tsetse distribution. The estimated prevalence was 4.17% by PCR compared to 2.48% by microscopy. Trypanosomes were detected in tsetse free areas. Trypanosoma vivax and Trypanosoma b. brucei were identified, but not the zoonotic Trypanosoma b. rhodesiense. This study demonstrated the importance of geospatial data analysis to understand the epidemiology of the parasite, to inform future research and formulate control strategies.

Activity-specific mobility of adults in a rural region of western Kenya

Improving rural household access to resources such as markets, schools and healthcare can help alleviate poverty in low-income settings. Current models of geographic accessibility to various resources rarely take individual variation into account due to a lack of appropriate data, yet understanding mobility at an individual level is key to knowing how people access their local resources. Our study used both an activity-specific survey and GPS trackers to evaluate how adults in a rural area of western Kenya accessed local resources. We calculated the travel time and time spent at six different types of resource and compared the GPS and survey data to see how well they matched. We found links between several demographic characteristics and the time spent at different resources, and that the GPS data reflected the survey data well for time spent at some types of resource, but poorly for others. We conclude that demography and activity are important drivers of mobility, and a better understanding of individual variation in mobility could be obtained through the use of GPS trackers on a wider scale.

Short report on implications of Covid-19 and emerging zoonotic infectious diseases for pastoralists and Africa

Many emerging and re-emerging zoonotic infectious diseases occur in Africa. These are projected to increase as human-animal host contact increases owing to increasing environmental degradation that shrinks nature habitats for wildlife over the continent. The current outbreak of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) responsible for causing coronavirus disease in 2019 (COVID-19) has reinvigorated discourse on the disruptiveness of the zoonotic emerging infectious diseases, owing to their transboundary character. Even as the world focuses on the COVID-19 sweeping pandemic, the Middle East respiratory syndrome coronavirus (MERS)-CoV re-emerged in Saudi Arabia infecting 18 people with five deaths; this has barely received any attention. This outbreak is particularly of concern to the pastoralists in the Horn of Africa, a region that has in recent past seen an increase in camel trade with the Gulf States, especially Yemen and Saudi Arabia. Emerging and re-emerging zoonotic infectious diseases are complex, depend on human-animal-environment interaction and pose a strain on public health systems. There is a need to address these diseases dynamically through a synergistic approach, drawing on expertise from diverse sectors. One Health approach has distinguished itself as an integrative action able to bring together multiple actors on a global, national and local scale to advance the attainment of optimal health outcomes for people, animals and the environment. One Health works by strengthening the preparedness, response, mitigation and monitoring of zoonotic infectious disease risks collaboratively. We opine that as zoonotic emerging and re-emerging infectious diseases continue to rise over pastoral Africa, comprehensive implementation of the One Health approach will be urgently required.

Agricultural land-uses consistently exacerbate infectious disease risks in Southeast Asia

Agriculture has been implicated as a potential driver of human infectious diseases. However, the generality of disease-agriculture relationships has not been systematically assessed, hindering efforts to incorporate human health considerations into land-use and development policies. Here we perform a meta-analysis with 34 eligible studies and show that people who live or work in agricultural land in Southeast Asia are on average 1.74 (CI 1.47-2.07) times as likely to be infected with a pathogen than those unexposed. Effect sizes are greatest for exposure to oil palm, rubber, and non-poultry based livestock farming and for hookworm (OR 2.42, CI 1.56-3.75), malaria (OR 2.00, CI 1.46-2.73), scrub typhus (OR 2.37, CI 1.41-3.96) and spotted fever group diseases (OR 3.91, CI 2.61-5.85). In contrast, no change in infection risk is detected for faecal-oral route diseases. Although responses vary by land-use and disease types, results suggest that agricultural land-uses exacerbate many infectious diseases in Southeast Asia.

One Health in Action: Operational Aspects of an Integrated Surveillance System for Zoonoses in Western Kenya

Surveillance of diseases in Kenya and elsewhere in East Africa is currently carried out by both human and animal health sectors. However, a recent evaluation highlighted the lack of integration between these sectors, leading to disease under-reporting and inefficiencies. This project aimed to develop an integrated and cost-effective surveillance and reporting system for 15 zoonotic diseases piloted in the counties of Bungoma, Busia, and Kakamega in western Kenya. Specifically, in this paper we describe the operational aspects of such a surveillance system. Interviews were carried out with key informants, and this was followed by field visits to identify sentinel sites and liaise with relevant stakeholders. Based on this information, a sampling strategy comprising 12 sentinel sites, 4 in each county, was developed. Each sentinel site comprised of a livestock market, 1-2 neighboring slaughter houses/slabs, and a hospital in the vicinity; each of the 12 sites, comprising 12 × 3 = 36 sampling locations, was visited every 4 weeks for 20 cycles. At each site, animal or patient sampling included a clinical examination and collection of blood, feces, and nasal swabs; in slaughtered animals, mesenteric lymph nodes, hydatid cysts, and flukes were also collected. At the end of each field visit, data on staff involved and challenges encountered were recorded, while biological samples were processed and tested for 15 zoonotic diseases in the field laboratory in Busia, Kenya. Public engagement sessions were held at each sentinel site to share preliminary results and provide feedback to both stakeholders and study participants. A livestock market visit lasted just over 3 h, and the most common challenge was the frequent refusals of animal owners to participate in the study. At the slaughterhouses, visits lasted just under 4 h, and challenges included poorly engaged meat inspectors or slaughter processes that were too quick for sampling. Finally, the hospital visits lasted around 4 h, and the most frequent challenges included low patients turn-out, frequent staff turn-over leading to poor institutional memory, and difficulty in obtaining patient stool samples. Our experiences have highlighted the importance of engaging with local stakeholders in the field, while also providing timely feedback through public engagement sessions, to ensure on-going compliance.

Control of Taenia solium; A Case for Public and Private Sector Investment

The zoonotic helminth T. solium is one of the leading causes of acquired epilepsy in endemic countries, resulting in a high burden both in human health and social stigma of affected people (1-3). In 2012 T. solium was highlighted as a priority for control in the World Health Assembly resolution 66.12 (4). Despite a call for validated control strategies by 2015 and a "Tool Kit" of control options being available, relatively few examples of successfully implemented and sustainable control programs are available (5-7). A minimal control strategy focusing solely on the porcine host has also been proposed although the cost-effectiveness of such has yet to be explored (8). Although acknowledgment has been made of the need for initiatives to be sustainable, we are yet to see sufficient consideration of the balance between the provision of public and private goods, and the need for engagement of the people and organizations in the pork value chains within T. solium control strategies. We utilized a food chain risk analysis model to determine the incremental cost-effectiveness ratio (ICER) in terms of $/infective meal avoided, of combining a pharmaceutical intervention in pigs with strengthened meat hygiene services. The addition of a vaccination and treatment protocol, at an additional 10.3% cost, was illustrated to have the potential to improve the ICER of improving meat inspection by 74.6%. The vaccination and treatment protocol also had the potential to reduce the losses borne by the pork industry of condemned meat by 66%, highlighting the potential to leverage private sector investment in T. solium control.

Systematic Review of Important Bacterial Zoonoses in Africa in the Last Decade in Light of the 'One Health' Concept

Zoonoses present a major public health threat and are estimated to account for a substantial part of the infectious disease burden in low-income countries. The severity of zoonotic diseases is compounded by factors such as poverty, living in close contact with livestock and wildlife, immunosuppression as well as coinfection with other diseases. The interconnections between humans, animals and the environment are essential to understand the spread and subsequent containment of zoonoses. We searched three scientific databases for articles relevant to the epidemiology of bacterial zoonoses/zoonotic bacterial pathogens, including disease prevalence and control measures in humans and multiple animal species, in various African countries within the period from 2008 to 2018. The review identified 1966 articles, of which 58 studies in 29 countries met the quality criteria for data extraction. The prevalence of brucellosis, leptospirosis, Q fever ranged from 0–40%, 1.1–24% and 0.9–28.2%, respectively, depending on geographical location and even higher in suspected outbreak cases. Risk factors for human zoonotic infection included exposure to livestock and animal slaughters. Dietary factors linked with seropositivity were found to include consumption of raw milk and locally fermented milk products. It was found that zoonoses such as leptospirosis, brucellosis, Q fever and rickettsiosis among others are frequently under/misdiagnosed in febrile patients seeking treatment at healthcare centres, leading to overdiagnoses of more familiar febrile conditions such as malaria and typhoid fever. The interactions at the human–animal interface contribute substantially to zoonotic infections. Seroprevalence of the various zoonoses varies by geographic location and species. There is a need to build laboratory capacity and effective surveillance processes for timely and effective detection and control of zoonoses in Africa. A multifaceted ‘One Health’ approach to tackle zoonoses is critical in the fight against zoonotic diseases. The impacts of zoonoses include: (1) Humans are always in contact with animals including livestock and zoonoses are causing serious life-threatening infections in humans. Almost 75% of the recent major global disease outbreaks have a zoonotic origin. (2) Zoonoses are a global health challenge represented either by well-known or newly emerging zoonotic diseases. (3) Zoonoses are caused by all-known cellular (bacteria, fungi and parasites) and noncellular (viruses or prions) pathogens. (4) There are limited data on zoonotic diseases from Africa. The fact that human health and animal health are inextricably linked, global coordinated and well-established interdisciplinary research efforts are essential to successfully fight and reduce the health burden due to zoonoses. This critically requires integrated data from both humans and animals on zoonotic diseases.

Household socio-economic position and individual infectious disease risk in rural Kenya

The importance of household socio-economic position (SEP) in shaping individual infectious disease risk is increasingly recognised, particularly in low income settings. However, few studies have measured the extent to which this association is consistent for the range of pathogens that are typically endemic among the rural poor in the tropics. This cross-sectional study assessed the relationship between SEP and human infection within a single community in western Kenya using a set of pathogens with diverse transmission routes. The relationships between household SEP and individual infection with Plasmodium falciparum, hookworm (Ancylostoma duodenale and/or Necator americanus), Entamoeba histolytica/dispar, Mycobacterium tuberculosis, and HIV, and co-infections between hookworm, P. falciparum and E. histolytica/dispar, were assessed using multivariable logistic and multinomial regression. Individuals in households with the lowest SEP were at greatest risk of infection with P. falciparum, hookworm and E. histolytica/dispar, as well as co-infection with each pathogen. Infection with M. tuberculosis, by contrast, was most likely in individuals living in households with the highest SEP. There was no evidence of a relationship between individual HIV infection and household SEP. We demonstrate the existence of a household socio-economic gradient within a rural farming community in Kenya which impacts upon individual infectious disease risk. Structural adjustments that seek to reduce poverty, and therefore the socio-economic inequalities that exist in this community, would be expected to substantially reduce overall infectious disease burden. However, policy makers and researchers should be aware that heterogeneous relationships can exist between household SEP and infection risk for different pathogens in low income settings.

Exploring fine-scale human and livestock movement in western Kenya

Human and livestock mobility are key factors in the transmission of several high-burden zoonoses such as rift valley fever and trypanosomiasis, yet our knowledge of this mobility is relatively poor due to difficulty in quantifying population-level movement patterns. Significant variation in the movement patterns of individual hosts means it is necessary to capture their fine-scale mobility in order to gain useful knowledge that can be extrapolated to a population level. Here we explore how the movements of people and their ruminants, and their exposure to various types of land cover, correlate with ruminant ownership and other demographic factors which could affect individual exposure to zoonoses. The study was conducted in Busia County, western Kenya, where the population are mostly subsistence farmers operating a mixed crop/livestock farming system. We used GPS trackers to collect movement data from 26 people and their ruminants for 1 week per individual in July/August 2016, and the study was repeated at the end of the same year to compare movement patterns between the short rainy and dry seasons respectively. We found that during the dry season, people and their ruminants travelled further on trips outside of the household, and that people spent less time on swampland compared to the short rainy season. Our findings also showed that ruminant owners spent longer and travelled further on trips outside the household than non-ruminant owners, and that people and ruminants from poorer households travelled further than people from relatively wealthier households. These results indicate that some individual-level mobility may be predicted by season and by household characteristics such as ruminant ownership and household wealth, which could have practical uses for assessing individual risk of exposure to some zoonoses and for future modelling studies of zoonosis transmission in similar rural areas.

Detection of circulating antigens for Taenia spp. in pigs slaughtered for consumption in Nairobi and surroundings, Kenya

Background & methods

Taenia solium a zoonotic tapeworm, responsible for neurocysticercosis in humans is a major public health threat, being a leading cause of acquired epilepsy in endemic regions. Eastern and southern African nations have experienced a recent rapid growth in pig production, including small-scale, free-range systems, with an accompanying increased risk of T. solium transmission. Seven hundred blood samples were collected from randomly selected pigs presented for slaughter at one of the largest porcine abattoir supplying unprocessed pork to Nairobi city and its surroundings. The samples were tested using an antigen ELISA to determine the prevalence of infection with Taenia spp.

Results

The prevalence, adjusted for diagnostic test characteristics, was estimated to be 4.4% (95% CI: 1.9–7.1) with no significant statistical difference by pig sex or age. Infection with Taenia spp. was detected in pigs from all regions of the country supplying pigs to this slaughterhouse. Official post-mortem inspection did not detect cysticercosis in the duration of the study. Therefore, all the carcasses entered the food chains of Nairobi (70%), or neighboring counties (30%).

Conclusions

Circulating antigens of Taenia spp. were detected in pigs slaughtered in one of the largest porcine slaughterhouses in Kenya, which receives pigs from several regions in the country. This is an indication that pigs entering the value chain are raised under poor husbandry conditions and that pork consumers in Nairobi and its surroundings may be exposed to the important zoonotic parasite. Whilst further research utilizing full carcass dissection is required to confirm T. solium positive cases, interventions to improve food-safety throughout the pork value chains in Kenya should be seriously considered.

•

Taenia spp. were detected in pigs (4.4%) slaughtered for Nairobi’s pork market.

•

Taenia spp. infections were present in pigs from each region in Kenya supplying pork to Nairobi during this study

•

A comprehensive risk assessment is necessary to identify exposure to food-safety hazards in pork value chain

•

Proper cooking of pork is recommended, as a way of reducing the risk of transmission of Taenia spp. to consumers

•

Interventions to improve food-safety should consider the full pork value-chain

General contextual effects on neglected tropical disease risk in rural Kenya

The neglected tropical diseases (NTDs) are characterized by their tendency to cluster within groups of people, typically the poorest and most marginalized. Despite this, measures of clustering, such as within-group correlation or between-group heterogeneity, are rarely reported from community-based studies of NTD risk. We describe a general contextual analysis that uses multi-level models to partition and quantify variation in individual NTD risk at multiple grouping levels in rural Kenya. The importance of general contextual effects (GCE) in structuring variation in individual infection with Schistosoma mansoni, the soil-transmitted helminths, Taenia species, and Entamoeba histolytica/dispar was examined at the household-, sublocation- and constituency-levels using variance partition/intra-class correlation co-efficients and median odds ratios. These were compared with GCE for HIV, Plasmodium falciparum and Mycobacterium tuberculosis. The role of place of residence in shaping infection risk was further assessed using the spatial scan statistic. Individuals from the same household showed correlation in infection for all pathogens, and this was consistently highest for the gastrointestinal helminths. The lowest levels of household clustering were observed for E. histolytica/dispar, P. falciparum and M. tuberculosis. Substantial heterogeneity in individual infection risk was observed between sublocations for S. mansoni and Taenia solium cysticercosis and between constituencies for infection with S. mansoni, Trichuris trichiura and Ascaris lumbricoides. Large overlapping spatial clusters were detected for S. mansoni, T. trichiura, A. lumbricoides, and Taenia spp., which overlapped a large cluster of elevated HIV risk. Important place-based heterogeneities in infection risk exist in this community, and these GCEs are greater for the NTDs and HIV than for TB and malaria. Our findings suggest that broad-scale contextual drivers shape infectious disease risk in this population, but these effects operate at different grouping-levels for different pathogens. A general contextual analysis can provide a foundation for understanding the complex ecology of NTDs and contribute to the targeting of interventions.

Epidemiology of Taenia saginata taeniosis/cysticercosis: a systematic review of the distribution in southern and eastern Africa

Background

The beef tapeworm, Taenia saginata, causing cysticercosis in bovines and taeniosis in humans, is thought to have a global distribution. In eastern and southern Africa, cattle production plays a crucial role in the economy, but a clear overview of the prevalence of T. saginata in the region is still lacking. This review aims to summarize existing knowledge on T. saginata taeniosis and bovine cysticercosis distribution in eastern and southern Africa.

Methods

A systematic review was conducted, that gathered published and grey literature, including OIE reports, concerning T. saginata taeniosis and bovine cysticercosis in eastern and southern Africa published between January 1st, 1990 and December 31st, 2017.

Results

A total of 1232 records were initially retrieved, with 78 full text articles retained for inclusion in the database. Unspecified taeniosis cases were reported for Angola, Ethiopia, Kenya, Madagascar, Malawi, South Africa, Tanzania, Uganda and Zambia, whereas T. saginata taeniosis cases were found for Ethiopia, Kenya, South Africa, Tanzania, Zambia and Zimbabwe. The prevalence of taeniosis ranged between 0.2–8.1% based on microscopy, and between 0.12–19.7% based on coproAg-ELISA. In Ethiopia, the percentage of tapeworm self-reporting was high (45.0–64.2%), and a substantial number of anthelmintic treatments were reported to be sold in towns. The presence of bovine cysticercosis was reported in all 27 countries/territories included in the study, except for Rwanda and Somalia, Comoros, Madagascar, Mauritius, Mayotte, Seychelles and Socotra. The prevalence of cysticercosis ranged between 0.02–26.3% based on meat inspection, and between 6.1–34.9% based on Ag-ELISA.

Conclusions

Although T. saginata has been reported in the majority of countries/territories of the study area, T. saginata taeniosis/cysticercosis remains a largely ignored condition, probably due to the absence of symptoms in cattle, the lack of data on its economic impact, and the fact that human taeniosis is considered a minor health problem. However, the occurrence of bovine cysticercosis is a clear sign of inadequate sanitation, insufficient meat inspection, and culinary habits that may favour transmission. Measures to reduce transmission of T. saginata are therefore warranted and the infection should be properly monitored.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3163-3) contains supplementary material, which is available to authorized users.

Systematic literature review of Rift Valley fever virus seroprevalence in livestock, wildlife and humans in Africa from 1968 to 2016

Background

Rift Valley fever virus (RVFV) is a zoonotic arbovirus that causes severe disease in livestock and humans. The virus has caused recurrent outbreaks in Africa and the Arabian Peninsula since its discovery in 1931. This review sought to evaluate RVFV seroprevalence across the African continent in livestock, wildlife and humans in order to understand the spatio-temporal distribution of RVFV seroprevalence and to identify knowledge gaps and areas requiring further research. Risk factors associated with seropositivity were identified and study designs evaluated to understand the validity of their results.

Methodology

The Preferred Reporting of Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used to produce a protocol to systematically search for RVFV seroprevalence studies in PubMed and Web of Science databases. The Strengthening the Reporting of Observational studies in Epidemiology (STROBE) statement guided the evaluation of study design and analyses.

Principal findings

A total of 174 RVFV seroprevalence studies in 126 articles fulfilled the inclusion criteria. RVFV seroprevalence was recorded in 31 African countries from 1968 to 2016 and varied by time, species and country. RVFV seroprevalence articles including either livestock and humans or livestock and wildlife seroprevalence records were limited in number (8/126). No articles considered wildlife, livestock and human seroprevalence concurrently, nor wildlife and humans alone. Many studies did not account for study design bias or the sensitivity and specificity of diagnostic tests.

Conclusions

Future research should focus on conducting seroprevalence studies at the wildlife, livestock and human interface to better understand the nature of cross-species transmission of RVFV. Reporting should be more transparent and biases accounted for in future seroprevalence research to understand the true burden of disease on the African continent.

Rift Valley fever virus (RVFV) is a vector-borne virus that infects wildlife and livestock, and can subsequently spread to humans. Due to the nature of the disease it has the potential to cause substantial economic and public health impacts. Rift Valley Fever (RVF) has been identified in Africa and the Arabian Peninsula, but has the potential to spread more widely. This systematic review assessed the distribution of RVF in livestock and humans in Africa by collating all the relevant studies we could find, extracting the data and critically evaluating them. Understanding when and where RVF has occurred in Africa and why some animals and humans get disease helps target control strategies and, in particular, those that reduce spread from livestock to humans. Furthermore, by evaluating past studies we can ensure that future ones are more robust and reproducible, so they can help us better understand the disease.

The topology of between-herd cattle contacts in a mixed farming production system in western Kenya

•

Degree of farm contact and the distances between farms were negatively correlated.

•

Disease control and surveillance to consider between farms contacts in the villages.

•

Heterogeneities in between farm contact may limit infectious disease spread.

In many livestock production systems in sub-Saharan Africa, cattle are owned by individual keepers but regularly mix with animals from other herds while grazing communal land, at watering points or through the use of shared bulls for breeding and ploughing. Such contacts may have important implications for disease transmission and control but are not well documented.

We describe between-farm contacts in Kimilili sub-county of Bungoma County, a mixed farming area of predominately smallholder farmers. Between-farm contacts occurring during grazing or at shared water points over the past four weeks were captured in seven randomly selected villages using a photo-elicitation tool. The use of shared bulls for breeding and ploughing and cattle introductions from farms within the same village in the past 12 months were also captured. Contact networks were constructed for each contact type in each village.

In total 329 farms were included in the study. Networks resembled undirected scale-free graphs with a network density ranging between 9.6 and 14.0. Between 45.6 and 100% of the farms in each study village had been in contact over the past four weeks through grazing and watering contacts. Between 88.9 and 100% were considered to have been in contact over the past 12 months. The topology of the networks was heterogeneous, with some farms exhibiting a high degree of contact. The degree of farm contact and distances between farms were negatively correlated (Pearson correlation coefficient range −0.2 to −0.4).

Effective disease control and surveillance must take into consideration the frequency and range of contacts that occur between farms within a single village. Cattle keepers are highly interconnected and pathogens that are transmitted through direct or indirect animal contact would be expected to spread rapidly in the study system. However, the observed heterogeneity in between-farm contact may present opportunities for interventions to be targeted to particular herds to limit infectious disease spread.

Increasing the Local Relevance of Epidemiological Research: Situated Knowledge of Cattle Disease Among Basongora Pastoralists in Uganda

Cattle disease can have severe negative impacts on the livelihoods of the poor, but still, animal disease management and outreach often remain suboptimal in low-income settings. In a study on Basongora pastoralists in Uganda, we examined local priorities, perceptions and practices regarding cattle disease, in order to improve outreach and disease control advisory work in such contexts. We also investigated how participatory epidemiology can be better equipped for gathering situated knowledge. Empirical material obtained in focus group discussions, interviews, participatory mapping, and wealth-ranking was used to perform a thematic, bottom-up analysis. The concepts of situated knowledge and embodied objectivity and insights from participatory research and interdisciplinary dialogue were applied to better embrace local perspectives. Cowdriosis, trypanosomosis, contagious bovine pleuropneumonia, East Coast fever and anthrax were high-priority diseases for participants. Lack of control over the animal health situation and money invested in treatments that did not guarantee recovery were of general importance for disease prioritization. Participants' descriptions of diseases sometimes diverged from textbook definitions. Co-infections, chronic and recurring infections and lack of access to formal knowledge were identified as important factors for differences between formal and situated knowledge. Paying attention to situated knowledge and particular context-specific issues such as proximity to a national park proved to be of special relevance for local understanding and experiences with disease. Another factor was the local importance ascribed to number of cattle, rather than production levels. These factors need to be taken into consideration when formulating disease control advice, as does the complex disease landscape. The results reveal the importance of moving research and advice beyond curing “knowledge-gaps” and creating different ways of understanding disease so that situated knowledge can be considered, and disease control improved.

Serological and spatial analysis of alphavirus and flavivirus prevalence and risk factors in a rural community in western Kenya

Alphaviruses, such as chikungunya virus, and flaviviruses, such as dengue virus, are (re)-emerging arboviruses that are endemic in tropical environments. In Africa, arbovirus infections are often undiagnosed and unreported, with febrile illnesses often assumed to be malaria. This cross-sectional study aimed to characterize the seroprevalence of alphaviruses and flaviviruses among children (ages 5-14, n = 250) and adults (ages 15 ≥ 75, n = 250) in western Kenya. Risk factors for seropositivity were explored using Lasso regression. Overall, 67% of participants showed alphavirus seropositivity (CI95 63%-70%), and 1.6% of participants showed flavivirus seropositivity (CI95 0.7%-3%). Children aged 10-14 were more likely to be seropositive to an alphavirus than adults (p < 0.001), suggesting a recent transmission period. Alphavirus and flavivirus seropositivity was detected in the youngest participants (age 5-9), providing evidence of inter-epidemic transmission. Demographic variables that were significantly different amongst those with previous infection versus those without infection included age, education level, and occupation. Behavioral and environmental variables significantly different amongst those in with previous infection to those without infection included taking animals for grazing, fishing, and recent village flooding. Experience of recent fever was also found to be a significant indicator of infection (p = 0.027). These results confirm alphavirus and flavivirus exposure in western Kenya, while illustrating significantly higher alphavirus transmission compared to previous studies.