A review on prevalence, control measure, and tolerance of Tanzania Shorthorn Zebu cattle to East Coast fever in Tanzania

Morbidity, mortality, and risk factors associated with seropositivity in a longitudinal calf study, Narok, Kenya

East Coast fever (ECF), caused by Theileria parva causes devastating loss to livestock keepers in sub-Saharan Africa. A longitudinal study was carried out in Narok County to estimate the incidence and risk factors associated with Theileria parva infection among calves. Calves were recruited within 5 weeks of birth and visited every six weeks to collect farm and calf level factors. A total of 1849 serum samples were collected and tested using an indirect enzyme-linked immunosorbent assay (ELISA). A multilevel multivariable logistic regression was used to determine associations between the seropositivity and different predictor variables. A total of 318 calves were recruited where 62 seroconverted during the follow up period. The overall risk of exposure was 26 %, with ECF-specific morbidity risk of 14.5 %. The cumulative incidence rate was 37 cases per 100 calf-years with higher incidence rate in agro-pastoral system. The crude mortality risk was 5.1 %, but four calves manifested classical signs of ECF resulting to clinical case-fatality risk of 44.4 %. In the final multivariable model, four variables were found to be significantly associated with T. parva seropositivity; calf age (OR 6.9; P < 0.01), calf sex (OR 1.4; P = 0.02), acaricide application (OR 0.5; P < 0.01) and spraying specific body parts (OR 2.5; P = 0.002). The results present the T. parva exposure patterns based on serological response in calves from birth to one year. These results will support evidence-based and effective practices for the management and control of ECF to mitigate the impact on productivity in the livestock sector.

Seroprevalence and risk factors associated with Theileria parva infection among calves in Narok County, Kenya

Background and Aim

East Coast fever (ECF), caused by Theileria parva, is a devastating disease that causes significant economic losses to cattle production in sub-Saharan Africa. Prevention and control of ECF are challenging in pastoral settings due to inadequate epidemiological information. This study aimed to estimate the seroprevalence and risk factors associated with T. parva infection among calves in different production systems to help design appropriate control interventions.

Materials and Methods

Blood samples were collected from 318 calves and tested using an indirect enzyme-linked immunosorbent assay targeting antibodies against polymorphic immunodominant molecules found on the surface of T. parva. Information on calf characteristics and management practices was also collected during sampling. Descriptive statistics and logistic regression were used to analyze potential risk factors, such as age and acaricide application, where p < 0.05 was considered significant.

Results

Of the 318 calves sampled, 41 (12.89%) were positive for T. parva, with a higher proportion in pastoral systems (36.58%) than in mixed farming systems (34.10%) and agropastoral systems (29.27%). From univariate analysis, calf age (p = 0.002), body weight (p = 0.001), suckling status (p = 0.026), rectal temperature (p = 0.06), calves on pasture (p = 0.022), other feeds (p = 0.004), feed grown within the farm (p = 0.004), acaricide application (p = 0.001), and acaricide application frequency (p = 0.001) were significantly associated with seropositivity. However, calf age (odds ratio [OR], 0.96; 95% confidence interval [CI], 0.91-0.99; p = 0.04), other feeds (OR, 8.82; 95% CI, 1.74-44.63; p = 0.009), and suckling status (OR, 0.38; 95% CI, 0.15-0.99; p = 0.05) were significantly associated with T. parva infection in the multivariable mixed logistic model.

Conclusion

T. parva is circulating in young calves in the study area (and possibly in cattle populations due to maternal transfer of antibodies to the calves). There is a need for molecular surveillance to determine the presence and burden of T. parva infection.

Molecular Investigation of Tick-Borne Haemoparasites Isolated from Indigenous Zebu Cattle in the Tanga Region, Tanzania

Tick-borne diseases (TBDs) are a major hindrance to livestock production in pastoral communities of Africa. Although information on tick-borne infections is necessary for setting up control measures, this information is limited in the pastoral communities of Tanzania. Therefore, this study aimed to provide an overview of the tick-borne infections in the indigenous cattle of Tanzania. A total of 250 blood samples were collected from the indigenous zebu cattle in the Tanga region, Tanzania. Then, we conducted a molecular survey using the polymerase chain reaction (PCR) and gene sequencing to detect and identify the selected tick-borne pathogens. The PCR was conducted using assays, based on Theileria spp. (18S rRNA), Theileria parva (p104), Theileria mutans and T. taurotragi (V4 region of the 18S rRNA), Babesia bigemina (RAP-1a), B. bovis (SBP-2), Anaplasma marginale (heat shock protein groEL) and Ehrlichia ruminantium (pCS20). The PCR screening revealed an overall infection rate of (120/250, 48%) for T. mutans, (64/250, 25.6%) for T. parva, (52/250, 20.8%) for T. taurotragi, (33/250, 13.2%) for B. bigemina and (81/250, 32.4%) for A. marginale. Co-infections of up to four pathogens were revealed in 44.8% of the cattle samples. A sequence analysis indicated that T. parva p104 and A. marginale groEL genes were conserved among the sampled animals with sequence identity values of 98.92−100% and 99.88−100%, respectively. Moreover, the B. bigemina RAP-1a gene and the V4 region of the 18S rRNA of T. mutans genes were diverse among the sampled cattle, indicating the sequence identity values of 99.27−100% and 22.45−60.77%, respectively. The phylogenetic analyses revealed that the T. parva (p104) and A. marginale (groEL) gene sequences of this study were clustered in the same clade. In contrast, the B. bigemina (RAP-1a) and the T. mutans V4 region of the 18S rRNA gene sequences appeared in the different clades. This study provides important basement data for understanding the epidemiology of tick-borne diseases and will serve as a scientific basis for planning future control strategies in the study area.

Laboratory analysis as support to slaughterhouse inspection in Songea cattle abattoir (Tanzania): A public health perspective

Livestock breeding is one of the main agricultural activities in Tanzania, recognized as one of the African countries with the greatest livestock resources. Cattle is the most widely bred animal species, especially with traditional farming methods such as pastoralism and agro-pastoralism. Slaughtering takes place mainly in rural slaughter slabs and municipal slaughterhouses, and according to local legislation it must be supervised by Official Veterinarians, who report any organs to be discarded and, after stamping the carcass, authorize its free consumption. Since the Ruvuma region lacks data on cattle diseases, the aim of this study was to collect information at Songea slaughterhouse, with particular attention to conditions of parasitic aetiology and potential zoonotic interest, deepening inspective diagnoses by means of parasitological and histological investigations on tissue samples. Overall, the slaughter data of 614 animals are reported. In most cases slaughtered cattle belonged to local breeds and came from the Mbeya region. Fasciolosis (diagnosed in 44.6% of animals) was the most frequent condition, followed by respiratory diseases (24.4%), aortic onchocerciasis (6.5%), hydatidosis (5.5%) and bovine cysticercosis (3.4%). Laboratory analysis identified Fasciola gigantica as the species involved in hepatic distomatosis in this area. Cases macroscopically ascribed to cysticercosis turned out to be a muscular form of onchocerciasis (by Onchocerca dukei), a neglected and unrecognised parasitic disease in Tanzania, questioning the real frequence of a zoonosis that causes primarily major economic losses. Pulmonary cysts, referred as hydatidosis at visual inspection, were histologically identified as haemal nodes, lymphoid organs common in ruminants, but described in cattle lungs for the first time in the present paper. Slaughterhouse is an important epidemiological observatory, especially for neglected parasitoses. The possibility of having basic laboratory diagnostics as an aid to visual inspection can ensure greater efficiency of veterinary services in the control of important livestock diseases and zoonoses, in the frame of a One Health perspective.

A cross-sectional survey to establish Theileria parva prevalence and vector control at the wildlife-livestock interface, Northern Tanzania

East Coast fever (ECF) in cattle is caused by the protozoan parasite Theileria parva, transmitted by Rhipicephalus appendiculatus ticks. In cattle ECF is often fatal, causing annual losses >$500 million across its range. The African buffalo (Syncerus caffer) is the natural host for T. parva but the transmission dynamics between wild hosts and livestock are poorly understood. This study aimed to determine the prevalence of T. parva in cattle, in a 30 km zone adjacent to the Serengeti National Park, Tanzania where livestock and buffalo co-exist, and to ascertain how livestock keepers controlled ECF and other vector-borne diseases of cattle. A randomised cross-sectional cattle survey and questionnaire of vector control practices were conducted. Blood samples were collected from 770 cattle from 48 herds and analysed by PCR to establish T. parva prevalence. Half body tick counts were recorded on every animal. Farmers were interviewed (n = 120; including the blood sampled herds) using a standardised questionnaire to obtain data on vector control practices. Local workshops were held to discuss findings and validate results. Overall prevalence of T. parva in cattle was 5.07% (CI: 3.70-7.00%), with significantly higher prevalence in older animals. Although all farmers reported seeing ticks on their cattle, tick counts were very low with 78% cattle having none. Questionnaire analysis indicated significant acaricide use with 79% and 41% of farmers reporting spraying or dipping with cypermethrin-based insecticides, respectively. Some farmers reported very frequent spraying, as often as every four days. However, doses per animal were often insufficient. These data indicate high levels of acaricide use, which may be responsible for the low observed tick burdens and low ECF prevalence. This vector control is farmer-led and aimed at both tick- and tsetse-borne diseases of livestock. The levels of acaricide use raise concerns regarding sustainability; resistance development is a risk, particularly in ticks. Integrating vaccination as part of this community-based disease control may alleviate acaricide dependence, but increased understanding of the Theileria strains circulating in wildlife-livestock interface areas is required to establish the potential benefits of vaccination.

Prioritizing smallholder animal health needs in East Africa, West Africa, and South Asia using three approaches: Literature review, expert workshops, and practitioner surveys

Managing the health needs of livestock contributes to reducing poverty and improving the livelihoods of smallholder and pastoralist livestock keepers globally. Animal health practitioners, producers, policymakers, and researchers all must prioritize how to mobilize limited resources. This study employed three approaches to prioritize animal health needs in East and West Africa and South Asia to identify diseases and syndromes that impact livestock keepers. The approaches were a) systematic literature review, b) a series of expert workshops, and c) a practitioner survey of veterinarians and para-veterinary professionals. The top constraints that emerged from all three approaches include endo/ ectoparasites, foot and mouth disease, brucellosis, peste des petits ruminants, Newcastle disease, and avian influenza. Expert workshops additionally identified contagious caprine pleuropneumonia, contagious bovine pleuropneumonia, mastitis, and reproductive disorders as constraints not emphasized in the literature review. Practitioner survey results additionally identified nutrition as a constraint for smallholder dairy and pastoralist small ruminant production. Experts attending the workshops agreed most constraints can be managed using existing veterinary technologies and best husbandry practices, which supports a shift away from focusing on individual diseases and new technologies towards addressing systemic challenges that limit access to veterinary services and inputs. Few research studies focused on incidence/ prevalence of disease and impact, suggesting better incorporation of socio-economic impact measures in future research would better represent the interests of livestock keepers.

Molecular detection and characterization of tick-borne haemoparasites among cattle on Zanzibar Island, Tanzania

Tick-borne diseases (TBDs) are serious constraints to livestock production in Tanzania and other tropical and subtropical countries and impact the livelihoods of resource-poor farming communities in the region. In Tanzania, detailed studies on tick-borne pathogens (TBPs) in cattle using sensitive molecular detection methods are scarce. The objective of this study was to investigate the occurrence and species composition of bovine TBPs in cattle kept in Zanzibar Island. A total of 236 blood samples were randomly collected in cattle population in June and July 2019. We used polymerase chain reaction (PCR) and gene sequencing to detect and identify pathogens. PCR screening of all 236 samples revealed that 64.5% of animals were infected by TBPs, including Theileria parva (34.3%), T. mutans (38.1%), T. taurotragi (30.9%), Anaplasma marginale (10.2%), Babesia bigemina (5.1%), T. velifera (3.4%) and B. bovis (2.1%). Overall a total of 86 animals (36.4%) were co-infected with up to five pathogens including T. parva, T. mutans, T. taurotragi, A. marginale and B. bigemina. The pathogens mostly involved in the co-infection were T. parva, T. taurotragi and T. mutans. Sequence analysis indicated that T. parva p104 and B. bigemina RAP1a genes are diverse among the sampled animals in Zanzibar Island, with 99.64%-100% and 99.51%-100% nucleotide sequence identity value respectively. In contrast, the A. marginale MSP-5, T. mutans 18S rRNA V4 region and B. bovis SBP-2 genes are conserved, with 100%, 99.05%-100% and 99.66%-100% nucleotide sequence identity values respectively. The phylogenetic analyses revealed that T. parva p104 and B. bigemina RAP1a gene sequences showed significant differences of genotypes, as they appear in different clades. Meanwhile, A. marginale MSP-5, T. mutans 18S rRNA V4 region and B. bovis SBP-2 gene sequences appear in the same clade with other sequences extracted from the NCBI GenBank. The epidemiological findings revealed in this study will provide important information on tick-borne diseases in Tanzania and will be used as scientific basis for planning future control strategies.

Diversity of two Theileria parva CD8+ antigens in cattle and buffalo-derived parasites in Tanzania

Theileria parva is a tick-transmitted protozoan parasite that causes a disease called East Coast fever (ECF) in cattle. This important tick borne-disease (TBD) causes significant economic losses in cattle in many sub-Saharan countries, including Tanzania. Cattle immunization using Muguga cocktail has been recommended as an effective method for controlling ECF in pastoral farming systems in Tanzania. However, immunity provided through immunization is partially strain-specific. Therefore, the control of ECF in Tanzania is still a challenge due to inadequate epidemiological information. This study was conducted to assess genetic diversity of Tp1 and Tp2 genes from T. parva isolates that are recognized by CD8 + T-cells in cattle and buffalo. The Tp1 and Tp2 genes are currently under evaluation as candidates for inclusion in a subunit vaccine. A total of 130 blood samples collected from cattle which do not interact with buffalo (98), cattle co-grazing with buffalo (19) and buffalo (13) in Mara, Mbeya, Morogoro, Tanga, and Coast regions in Tanzania were used in this study. Genomic DNA was extracted from the blood samples, Tp1 and Tp2 genes were amplified using nested PCR and the PCR products were purified and sequenced. The partial sequencing of the Tp1 and Tp2 genes from T. parva isolates exhibited polymorphisms in both loci, including the epitope-containing regions. Results for sequence analysis showed that the overall nucleotide polymorphism (π) was 0.7% and 13.5% for Tp1 and Tp2, respectively. The Tajima's D and Fu's Fs test showed a negative value for both Tp1 and Tp2 genes, indicating deviations from neutrality due to a recent population expansion. The study further revealed a low to high level of genetic differentiations between populations and high genetic variability within populations. The study also revealed that most samples from the seven populations possessed several epitopes in antigens that were identical to those in the T. parva Muguga reference stock, which is the main component of the widely used live vaccine cocktail. Therefore, different strategic planning and cost-effective control measures should be implemented in order to reduce losses caused by ECF in the study areas.

Combining Landscape Genomics and Ecological Modelling to Investigate Local Adaptation of Indigenous Ugandan Cattle to East Coast Fever

East Coast fever (ECF) is a fatal sickness affecting cattle populations of eastern, central, and southern Africa. The disease is transmitted by the tick Rhipicephalus appendiculatus, and caused by the protozoan Theileria parva parva, which invades host lymphocytes and promotes their clonal expansion. Importantly, indigenous cattle show tolerance to infection in ECF-endemically stable areas. Here, the putative genetic bases underlying ECF-tolerance were investigated using molecular data and epidemiological information from 823 indigenous cattle from Uganda. Vector distribution and host infection risk were estimated over the study area and subsequently tested as triggers of local adaptation by means of landscape genomics analysis. We identified 41 and seven candidate adaptive loci for tick resistance and infection tolerance, respectively. Among the genes associated with the candidate adaptive loci are PRKG1 and SLA2. PRKG1 was already described as associated with tick resistance in indigenous South African cattle, due to its role into inflammatory response. SLA2 is part of the regulatory pathways involved into lymphocytes' proliferation. Additionally, local ancestry analysis suggested the zebuine origin of the genomic region candidate for tick resistance.

Immune parameters to p67C antigen adjuvanted with ISA206VG correlate with protection against East Coast fever

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Three doses of p67C antigen generated stronger immune responses than two doses.

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Antibody titers and CD4⁺ T-cell proliferation correlated with protection against ECF.

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The number of doses could not be reduced from three to two without compromising the protection.

East Coast fever (ECF) is a lymphoproliferative disease caused by the tick-transmitted protozoan parasite Theileria parva. ECF is one of the most serious cattle tick-borne diseases in Sub-Saharan Africa. We have previously demonstrated that three doses of the C-terminal part of the sporozoite protein p67 (p67C) adjuvanted with ISA206VG confers partial protection against ECF at a herd level. We have tested the efficacy of two doses of this experimental vaccine, as reducing the vaccination regimen would facilitate its deployment in the field. We reconfirm that three antigen doses gave a significant level of protection to severe disease (46%, ECF score < 6) when compared with the control group, while two doses did not (23%). Animals receiving three doses of p67C developed higher antibody titers and CD4⁺ T-cell proliferation indices, than those which received two doses. A new panel of immune parameters were tested in order to identify factors correlating with protection: CD4⁺ proliferation index, total IgG, IgG1, IgG2 and IgM half maximal titers and neutralization capacity of the sera with and without complement. We show that some of the cellular and humoral immune responses provide preliminary correlates of protection.

Exploring knowledge and management practices on ticks and tick-borne diseases among agro-pastoral communities in Southern Highlands, Tanzania

Aim

The current study was conducted to assess the farmers' knowledge and management practices on ticks and tick-borne diseases (TBDs) through individual interview using a structured questionnaire in Mbarali and Momba districts of Mbeya region.

Materials and Methods

A total of 240 households, 120 from each district were asked to mention TBDs of cattle which they thought were the most important in their localities and period of the year when the diseases occurred more frequently. In addition, farmers were asked to describe clinical signs and management practices associated with the common TBDs that they knew.

Results

The majority of respondents (46.2%) reported that East Coast fever (ECF) was the most important disease of cattle in the region, followed by anaplasmosis (33.8%), heartwater (15.4%), and babesiosis (4.6%). According to the farmers, ECF and anaplasmosis occurred more frequently during the dry season, while babesiosis and heartwater occurred more frequently during the rainy season. The majority of farmers were able to describe properly the signs of the common TBDs. Most farmers (80.4%) reported that they used acaricide to control ticks at a frequency of after every 2 weeks and a small proportion (15.8%) vaccinated their animals against ECF.

Conclusion

It can be concluded that farmers in Mbeya have considerable knowledge on tick species and clinical signs of TBDs affecting their cattle. Based on the findings of the current study, it is recommended that integrated approach to the control of ticks and TBDs be adopted in the study area and many other areas that utilize agro-pastoral and pastoral cattle production systems.

Seasonal occurrence of Theileria parva infection and management practices amongst Maasai pastoralist communities in Monduli District, Northern Tanzania

Theileria parva causes an economically devastating tick-borne disease called East Coast fever (ECF), which affects cattle in central, eastern and southern Africa. Determination of seasonal infection rates for T. parva is crucial for epidemiological understanding and for strengthening ECF management practices. However, this information is lacking for most pastoralist areas with high livestock density, such as the Monduli District in the Maasai steppe, northern Tanzania. A cross-sectional study was carried out to estimate the prevalence of T. parva in wet and dry seasons, and to assess understanding of management practices associated with T. parva amongst pastoralists' cattle. A total of 960 cattle owned by 130 pastoralists were randomly selected from ten study villages in each season and blood samples analysed for T. parva prevalence using a nested polymerase chain reaction (PCR). Seroprevalence for T. parva in the wet season was assessed using an enzyme-linked-immunosorbent assay (ELISA). Information on relevant management practices was gathered using a standardized questionnaire. Multivariable logistic regression was used to evaluate the association between T. parva parasitaemia and animal, farm and village-level factors. The prevalence of T. parva parasitaemia was 15.9% (95% CI=0.13-0.19) and 31.6% (95% CI=0.28-0.36) in wet and dry seasons, respectively. All cattle were sero-positive. T. parva parasitaemia was significantly associated with age of the animal, sampling season, and study village. All 130 cattle owners interviewed (100%) reported that they could easily recognise ECF and the vast majority (97.7%) identified swollen lymph nodes as the most prominent sign. At least 70% reported to understand the involvement of R. appendiculatus in ECF transmission. The use of both commercial drugs and herbal medicines for ECF treatment was reported by 54.6% of cattle owners. Among commercial drugs reported, the most commonly used was alamycin 300mg/ml (oxytetracycline dehydrates). Tick control by hand spraying was reported by the majority (90.8%) of cattle owners and less than half (45.4%) reported to vaccinate their cattle. This research provides evidence of widespread T. parva infection across Monduli District, and baseline information on seasonal occurrence. This information can assist the planning of more appropriate control strategies in pastoralist communities both now and into the future as predicted climatic changes progress in the region and potentially influence ECF occurrence and transmission.

Climate change and cattle vector-borne diseases: Use of participatory epidemiology to investigate experiences in pastoral communities in Northern Tanzania

Climate change is predicted to increase incidence of vector-borne diseases in humans, however, little is known about the impact of such diseases in livestock. In the absence of historical data with which to examine the inter-relation between climate and disease, participatory epidemiological (PE) methods were used with Maasai pastoralists of Monduli District, northern Tanzania to establish local observations on two major vector-borne diseases of cattle, namely East Coast fever (ECF) and African animal trypanosomiasis (AAT). Data collection involving gender segregated groups (10 men groups and 9 women groups) occurred in 10 randomly selected villages between November 2014 and March 2015. ECF and AAT were ranked amongst the top 5 most important cattle diseases with strong agreement across informant groups (Kendall's W=0.40 for men and 0.45 for women; p<0.01). Matrix scoring for both men and women groups confirmed that Masaai easily recognize these diseases. All groups associated ECF with the wet and cool dry seasons. AAT was more variable throughout the year, with more cases reported in the long dry season. Likewise, pastoralists reported differences in seasonal occurrence of disease vectors (Rhipicephalus appendiculatus and Glossina spp.) by village. Comparing 2014-1984, participant groups consistently reported declines in rainfall, vegetation cover and quality pasture, as well as increases in severe droughts. Experiences with ECF/AAT and vector abundance between these time periods was more variable across villages, and likely relates to changes in climate and animal management practices over the last 30 years. This baseline study is the first to document the inter-relation between climate and cattle vector-borne disease from the pastoralist perspective. Findings from this study reveal a complex interplay between human, animal and environmental factors, understanding of which is urgently required to devise approaches to mitigate effects of climate change in these vulnerable areas.

Prevalence and risk factors associated with Theileria parva infection in cattle in three regions of Tanzania

Ticks and tickborne diseases (TBDs) are serious constraints to cattle production in Tanzania and other tropical and subtropical countries. Among the TBDs, East Coast fever (ECF) is the most important as it causes significant economic losses to the cattle industry in Tanzania. However, control of ECF in Tanzania has continued to be a challenge due to inadequate epidemiological information. The main objective of this study was to determine the epidemiological situation of Theileria parva infections in cattle kept under pastoral and agro-pastoral farming systems in Mara, Singida, and Mbeya regions of Tanzania. Blood samples were collected from 648 cattle in the three regions. Genomic DNA was extracted and amplified in a polymerase chain reaction (PCR) using T. parva-specific primers targeting the 104-kD antigen (P104) gene. In addition, information was collected on the possible risk factors of T. parva infection (animal age, region, animal sex, tick burden, tick control method, and frequency of acaricide application). The prevalence of T. parva across the three regions was 14.2%. There was variation in prevalence among the three regions with Mara (21.8%) having a significantly higher (p = 0.001) prevalence than the other regions. Moreover, Mbeya exhibited relatively lower prevalence (7.4%) compared to the other regions. Factors found to be significantly associated with an animal being PCR positive for T. parva were region (p = 0.001) and tick burden (p = 0.003). Other factors were not found to be significant predictors of being PCR positive for T. parva. The present study showed high variation in tick burden and T. parva prevalence across the regions. Therefore, different strategic planning and cost-effective control measures for ticks and T. parva infection should be implemented region by region in order to reduce losses caused by ticks and ECF in the study area.