Heterogeneity in the prevalence and intensity of bovine trypanosomiasis in the districts of Amuru and Nwoya, Northern Uganda

Comparative evaluation of rapid diagnostic test and PCR-based diagnostic assay for identification of trypanosomes in cattle of Apac and Kiryandongo districts, Uganda: A cross sectional study

BACKGROUND

Diagnostic tests and knowledge of their diagnostic accuracies are important for animal trypanosomosis surveillance and treatment.

METHODOLOGY

A cross-sectional study was conducted in November 2021 to compare the performance of rapid diagnostic test (RDT) and PCR-based assay for the detection of trypanosome infections. Random sampling and probability proportional to size sampling were used to sample study households and animals from the sampled household respectively. Animals were screened for the presence of trypanosomes using both tests. A total of 100 cattle (52 from Apac and 48 from Kiryandongo districts) were included in the study. The percentage of positive tests, sensitivity, and specificity of the tests using mini PCR as a reference were computed. Cohen's kappa statistics was computed to assess how well the rapid diagnostic test agrees with the mini PCR. McNemar's statistic assessed if the proportion of positive tests identified by mini PCR significantly differed from that identified by the rapid diagnostic test.

RESULTS

The mini PCR test detected 31.2% Trypanosome spp positive samples in Kiryandongo while it detected only 5.7% positive samples in Apac district. The rapid diagnostic test (RDT) analysis detected 91.6% Trypanosome spp positive samples in Kiryandongo district and only 46.1% in Apac district. T. congolense was the most common Trypanosoma species identified in Apac (36.5%) and Kiryandongo (47.9%) by the RDT. The percentage of each of the Trypanosome species (T.vivax, T.congolense, and mixed infection of T.vivax and T. congolense) detected by RDT differed significantly (p < 0.001) between the two districts. The RDT had a high sensitivity of 94.4% (95% Confidence Interval (CI): 72.7-99.9) but a very low specificity of 36.6% (95% CI: 26.2-48.0). The kappa test showed evidence of only a slight agreement (kappa = 0.1547, Accuracy = 0.48 (95% Confidence Interval (CI): 0.379,0.5822) between the two tests. The observed agreement between the tests was 47% while the expected agreement was 37.84%.

CONCLUSION

This study found high sensitivity but low specificity of RDT using mini PCR as a reference.

Clinical and epidemiological investigation of human infection with zoonotic parasite Trypanosoma dionisii in China

BACKGROUND

Trypanosomiasis continues to pose a global threat to human health, with human infection mainly caused by Trypanosoma brucei and Trypanosoma cruzi.

METHODS

We present a 30-year-old pregnant woman with persistent high fever from Shandong Province, China. High-throughput sequencing revealed the presence of Trypanosoma dionisii in blood. We conducted an analysis of the patient's clinical, epidemiological, and virological data.

RESULTS

The patients exhibited fever, shortness of breath, chest tightness, accompanied by change in liver function and inflammatory response. She made a full recovery without any long-term effects. T. dionisii was detected in blood collected 23 days after onset of illness. The 18S rRNA gene sequence showed close similarity to T. dionisii found in bats from Japan, while the gGAPDH gene was closely related to T. dionisii from bats in Mengyin County, Shandong Province. Phylogenetic analysis demonstrated the current T. dionisii belongs to clade B within its species group. Positive anti-Trypanosoma IgG antibody was detected from the patient on Day 23, 66 and 122 after disease onset, as well as the cord blood and serum from the newborn. Retrospective screening of wild small mammals captured from Shandong Province revealed a prevalence rate of 0.54% (7/1304) for T. dionisii; specifically among 0.81% (5/620) of Apodemus agrarius, and 0.46% (2/438) of Mus musculus.

CONCLUSIONS

The confirmation of human infection with T. dionisii underscores its potential as a zoonotic pathogen, while the widespread presence of this parasite in rodent and bat species emphasizes the emerging threat it poses to human health.

Serological and molecular diagnosis of Trypanosoma vivax on buffalos (Bubalus bubalis) and their ectoparasites in the lowlands of Maranhão, Brazil

The aim of this study was to detect trypomastigote forms of Trypanosoma vivax, in blood smears, DNA of T. vivax and anti-T. vivax antibodies in samples from buffalos reared in the lowlands of Maranhão, Brazil. Blood samples were collected from 116 buffalos and 25 ectoparasite specimens. Blood smears were produced to diagnose forms compatible with Trypanosoma spp.; the indirect enzyme-linked immunosorbent assay (iELISA) and lateral-flow immunochromatography (Imunotest®) serological tests were used; and the polymerase chain reaction (PCR) was used to make molecular diagnoses. No forms compatible with Trypanosoma spp. were observed in blood smears. Among the 116 serum samples analyzed, 79.31% and 76.72% were positive in the ELISA and rapid tests, respectively. One sample was positive in the molecular test. Twenty-five lice of the species Haematopinus tuberculatus were collected. When subjected to PCR for detection of DNA of T. vivax, all of them were negative. The louse specimens were negative for T. vivax. There were no statistically significant differences (p < 0.05) in the presence of T. vivax in this region, in relation to the animals' age and sex. It can be concluded that these protozoa are circulating in the buffalo herd of the lowlands of Maranhão displaying crypitc parasitemias.

A systematic review and meta-analysis on prevalence of bovine trypanosomosis in East Africa

Bovine trypanosomosis is an incapacitating and lethal ailment brought about by protozoan parasites of the genus Trypanosoma. The disease leads to losses in livestock and agricultural productivity, resulting in significant socio-economic repercussions. In East Africa, trypanosomosis has been endemic for an extensive period due to ecological factors and vector biology that facilitate the persistent circulation of trypanosomes. This investigation outlines the occurrence of bovine trypanosomosis in East Africa through a meta-analysis. A thorough search was conducted on PubMed, Google Scholar, Scopus, Web of Science and AJOL. Suitable studies were chosen using inclusion and exclusion criteria. The prevalence was estimated through a random effect model. Publication bias and the variation in prevalence estimates due to heterogeneity were also evaluated. The analysis was performed on 115 studies that contained relevant prevalence data. The collective estimate of bovine trypanosomosis prevalence across the studies stood at 12% (95% CI: 11, 13), ranging from 1% (95% CI: 0, 2) to 51% (95% CI: 45, 58). The subgroup analysis by country revealed considerable disparities in prevalence. The highest estimated prevalence was 24% (95% CI: 18, 30) in Somalia, whereas the lowest prevalence was observed in Ethiopia at 10% (95% CI: 9, 11). A significant level of heterogeneity was noted in most pooled estimates, even after conducting subgroup analysis. The visual examination of the funnel plot and the Egger's regression asymmetry coefficient (b = -5.13, 95% CI: -7.49, -2.76, p = 0.00) and Begg's plot (p = 0.00) indicate the presence of publication bias. In conclusion, bovine trypanosomosis is a pervasive and noteworthy malady affecting livestock. The findings of this investigation imply a high prevalence of bovine trypanosomosis in the majority of the countries under scrutiny. Despite the well-known hindrance that livestock trypanosomosis poses to livestock production in Africa, little attention has been devoted to the trypanosomosis situation, particularly in East African nations.

Seasonal dynamics and genetic characterization of bovine arthropod-borne parasites in Nan Province, Thailand with molecular identification of Anaplasma platys and Trypanosoma theileri

Virulent species or strains of hematophagous borne pathogens such as Anaplasma spp., Babesia spp., Theileria spp., and Trypanosoma spp., are lethal to susceptible animals or reduce their productivity on a global scale. Nonetheless, efforts to diagnose the causative agents and assess the genotypic profiles as well as quantify the parasite burden of aforementioned parasites across seasons remain limited. Therefore, the present investigation sought to elucidate the genotypic composition of Anaplasma spp., Babesia spp., Theileria spp., and Trypanosoma spp. The findings revealed heightened infection rates during the summer, manifesting a correlation between Trypanosoma spp. infection and seasonal fluctuations. Among the identified pathogens, Anaplasma marginale emerged as the most dominant species, while the occurrence of Anaplasma platys in Thai cattle was confirmed via the sequencing of the groEL gene. Moreover, the study successfully identified two lineages of Trypanosoma theileri. The findings of this investigation offer valuable insights that can inform the development of preventive strategies for vector-borne diseases, such as considering the appropriate use of insect repellent, mosquito or insect nets, or eliminating breeding places for insects in each season.

Prevalence of African animal trypanosomiasis among livestock and domestic animals in Uganda: a systematic review and meta-regression analysis from 1980 to 2022

African animal trypanosomiasis (AAT) is one of the major constraints to animal health and production in sub-Saharan Africa. To inform AAT control in Uganda and help advance along the progressive control pathway (PCP), we characterized AAT prevalence among eight host species in Uganda and explored factors that influence the prevalence variation between studies. We retrieved AAT prevalence publications (n = 2232) for Uganda (1980-2022) from five life sciences databases, focusing on studies specifying AAT detection methods, sample size, and the number of trypanosome-positive animals. Following PRISMA guidelines, we included 56 publications, and evaluated publication bias by the Luis Furuya-Kanamori (LFK) index. National AAT prevalence under DNA diagnostic methods for cattle, sheep and goats was 22.15%, 8.51% and 13.88%, respectively. Under DNA diagnostic methods, T. vivax was the most common Trypanosoma sp. in cattle (6.15%, 95% CI: 2.91-10.45) while T. brucei was most common among small ruminants (goats: 8.78%, 95% CI: 1.90-19.88, and sheep: 8.23%, 95% CI: 4.74-12.50, respectively). Northern and Eastern regions accounted for the highest AAT prevalence. Despite the limitations of this study (i.e., quality of reviewed studies, underrepresentation of districts/regions), we provide insights that could be used for better control of AAT in Uganda and identify knowledge gaps that need to be addressed to support the progressive control of AAT at country level and other regional endemic countries with similar AAT eco-epidemiology.

The economic cost of bovine trypanosomosis in pastoral and ago pastoral communities surrounding Murchision Falls National park, Buliisa district, Uganda

Background:

Animal diseases that are endemic like tsetse transmitted trypanosomosis cause the continuous expenditure of financial resources of livestock farmers and loss of productivity of livestock. Estimating the cost of controlling animal trypanosomosis can provide evidence for priority setting and targeting cost-effective control strategies.

Methodology:

A cross-sectional survey to estimate the economic cost of bovine trypanosomosis was conducted in cattle-keeping communities living around Murchision falls National Park, in Buliisa district Uganda. Data was collected on herd structure, the cost of treatment and control, prevalence of morbidity and mortality rates due to trypanosomosis, and salvage sales losses in cattle herds in the last year.

Results:

In this study, 55.4% (n = 87) of the households reported their cattle had been affected by trypanosomosis during the previous last year. There was a high economic cost of trypanosomosis (USD 653) per household in cattle-keeping communities in Buliisa district of which 83% and 9% were due to mortality and milk loss respectively/ High mortality loss was due to low investment in treatment. The study showed that prophylactic treatment 3 times a year of the whole herd of cattle using Samorin ® (Isometamidium chloride) at a cost of USD 110 could drastically reduce cattle mortality loss due to trypanosomosis due to trypanosomosis with a return on investment of USD 540 annually per herd. This could be coupled with strategic restricted insecticide spraying of cattle with deltamethrin products.

Conclusion:

The results show a high economic cost of trypanosomosis in cattle-keeping communities in Buliisa district, with cattle mortality contributing the largest proportion of the economic cost. The high mortality loss was due to low investment in treatment of sick cattle.

African Animal Trypanosomiasis: A Systematic Review on Prevalence, Risk Factors and Drug Resistance in Sub-Saharan Africa

African animal trypanosomiasis (AAT) a parasitic disease of livestock in sub-Saharan Africa causing tremendous loses. Sub-Saharan continental estimation of mean prevalence in both large and small domestic animals, risk factors, tsetse and non-tsetse prevalence and drug resistance is lacking. A review and meta-analysis was done to better comprehend changes in AAT prevalence and drug resistance. Publish/Perish software was used to search and extract peer-reviewed articles in Google scholar, PubMed and CrossRef. In addition, ResearchGate and African Journals Online (AJOL) were used. Screening and selection of articles from 2000-2021 was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Articles 304 were retrieved; on domestic animals 192, tsetse and non-tsetse vectors 44, risk factors 49 and trypanocidal drug resistance 30. Prevalence varied by, host animals in different countries, diagnostic methods and species of Trypanosoma. Cattle had the highest prevalence with Ethiopia and Nigeria leading, T. congolense (11.80-13.40%) and T. vivax (10.50-18.80%) being detected most. This was followed by camels and pigs. Common diagnostic method used was buffy coat microscopy. However; polymerase chain reaction (PCR), CATT and ELISA had higher detection rates. G. pallidipes caused most infections in Eastern regions while G. palpalis followed by G. mortisans in Western Africa. Eastern Africa reported more non-tsetse biting flies with Stomoxys leading. Common risk factors were, body conditions, breed type, age, sex and seasons. Ethiopia and Nigeria had the highest trypanocidal resistance 30.00-35.00% and highest AAT prevalence. Isometamidium and diminazene showed more resistance with T. congolense being most resistant species 11.00-83.00%.

Apparent density, trypanosome infection rates and host preference of tsetse flies in the sleeping sickness endemic focus of northwestern Uganda

Background

African trypanosomiasis, caused by protozoa of the genus Trypanosoma and transmitted by the tsetse fly, is a serious parasitic disease of humans and animals. Reliable data on the vector distribution, feeding preference and the trypanosome species they carry is pertinent to planning sustainable control strategies.

Methodology

We deployed 109 biconical traps in 10 villages in two districts of northwestern Uganda to obtain information on the apparent density, trypanosome infection status and blood meal sources of tsetse flies. A subset (272) of the collected samples was analyzed for detection of trypanosomes species and sub-species using a nested PCR protocol based on primers amplifying the Internal Transcribed Spacer (ITS) region of ribosomal DNA. 34 blood-engorged adult tsetse midguts were analyzed for blood meal sources by sequencing of the mitochondrial cytochrome c oxidase 1 (COI) and cytochrome b (cytb) genes.

Results

We captured a total of 622 Glossina fuscipes fuscipes tsetse flies (269 males and 353 females) in the two districts with apparent density (AD) ranging from 0.6 to 3.7 flies/trap/day (FTD). 10.7% (29/272) of the flies were infected with one or more trypanosome species. Infection rate was not significantly associated with district of origin (Generalized linear model (GLM), χ² = 0.018, P = 0.895, df = 1, n = 272) and sex of the fly (χ2 = 1.723, P = 0.189, df = 1, n = 272). However, trypanosome infection was highly significantly associated with the fly’s age based on wing fray category (χ² = 22.374, P < 0.001, df = 1, n = 272), being higher among the very old than the young tsetse. Nested PCR revealed several species of trypanosomes: T. vivax (6.62%), T. congolense (2.57%), T. brucei and T. simiae each at 0.73%. Blood meal analyses revealed five principal vertebrate hosts, namely, cattle (Bos taurus), humans (Homo sapiens), Nile monitor lizard (Varanus niloticus), African mud turtle (Pelusios chapini) and the African Savanna elephant (Loxodonta africana).

Conclusion

We found an infection rate of 10.8% in the tsetse sampled, with all infections attributed to trypanosome species that are causative agents for AAT. However, more verification of this finding using large-scale passive and active screening of human and tsetse samples should be done. Cattle and humans appear to be the most important tsetse hosts in the region and should be considered in the design of control interventions.

Prevalence and risk factors for trypanosome infection in cattle from communities surrounding the Murchison Falls National Park, Uganda

Background

Bovine trypanosomosis transmitted by tsetse flies is a major constraint to cattle health and productivity in all sub-Saharan countries, including Uganda. The objectives of this study were to determine the prevalence of bovine trypanosomosis and identify its associated risk factors and the species of trypanosomes associated with the disease.

Methodology

A cross-sectional study was conducted around Murchison Falls National Park, Uganda from January 2020 to April 2020. Trypanosomes were detected in blood samples by PCR analysis targeting the internal transcribed spacer 1 (ITS-PCR assays), and trypanosomes in positive blood samples were sequenced.

Results

Of 460 blood samples collected and tested, 136 (29.6%) were positive for trypanosome infections and 324 (70.4%) were negative. The overall trypanosome prevalence was 29.6% (95% confidence interval 25.4–33.8%), attributed to three trypanosome species. Of these three species, Trypanosoma vivax was the most prevalent (n = 130, 28.3%) while the others were detected as mixed infections: T. vivax + Trypanosomacongolense (n = 2, 0.4%) and T. vivax + Trypanosomaevansi (n = 1, 0.2%). There were significant differences in trypanosome prevalence according to sex (χ² = 62, df = 1, P < 0.05), age (χ² = 6.28, df = 2, P = 0.0043) and cattle breed (χ² = 10.61, df = 1, P = 0.001).

Conclusions

Trypanosomosis remains a major limitation to cattle production around Murchison Falls National Park and interventions are urgently needed. In our study, the prevalence of trypanosome infections was high, with T. vivax identified as the most prevalent species. Age, sex and breed of cattle were risk factors for trypanosome infection.

Graphical Abstract

Knowledge, attitudes and practices on bovine trypanosomosis control in pastoral and agro pastoral communities surrounding Murchison Falls National Park, Uganda

A mixed method survey was conducted among pastoral and agro pastoral communities surrounding Murchison Falls National Park, Uganda to assess knowledge, attitudes and practices about control of bovine trypanosomosis. A total of 96.8% (n = 152) of the participants had seen tsetse flies, and close to 91.7% (n = 116) of the participants had heard about bovine trypanosomosis. Bovine trypanosomosis was reported as a major disease in their area by about 73.9% (n = 116). There was a significant difference (P < 0.05) in the level of awareness and perception about tsetse and bovine trypanosomosis across the study sub counties. The majority of the farmers (60.5%) stated that grazing near national parks was the main cause of bovine trypanosomosis. A small proportion of farmers associated sharing grazing land and watering points with wildlife (19.1%) and grazing cattle in tsetse fly-infested areas (8.3%) as the causes of trypanosomosis. The communities in the study sub counties were aware of at least one or two clinical signs of bovine trypanosomosis. Spraying cattle with insecticide and avoiding grazing animals in tsetse-infested areas were the control practices. Curative trypanocides were mainly used to treat their cattle against trypanosomosis. Bush clearing, targets and traps as tsetse fly control measures were less practiced by the farmers. Treatment of cattle was based on observation of clinical signs due to absence of blood diagnostic facilities. Implementing regular tsetse fly population monitoring surveys and promotion of disease rapid diagnostic tools at farm level as long-term strategies are key for effective control of the disease.

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.

Global distribution, host range and prevalence of Trypanosoma vivax: a systematic review and meta-analysis

BACKGROUND

Trypanosomosis caused by Trypanosoma vivax is one of the diseases threatening the health and productivity of livestock in Africa and Latin America. Trypanosoma vivax is mainly transmitted by tsetse flies; however, the parasite has also acquired the ability to be transmitted mechanically by hematophagous dipterans. Understanding its distribution, host range and prevalence is a key step in local and global efforts to control the disease.

METHODS

The study was conducted according to the methodological recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. A systematic literature search was conducted on three search engines, namely PubMed, Scopus and CAB Direct, to identify all publications reporting natural infection of T. vivax across the world. All the three search engines were screened using the search term Trypanosoma vivax without time and language restrictions. Publications on T. vivax that met our inclusion criteria were considered for systematic review and meta-analysis.

RESULT

The study provides a global database of T. vivax, consisting of 899 records from 245 peer-reviewed articles in 41 countries. A total of 232, 6277 tests were performed on 97 different mammalian hosts, including a wide range of wild animals. Natural infections of T. vivax were recorded in 39 different African and Latin American countries and 47 mammalian host species. All the 245 articles were included into the qualitative analysis, while information from 186 cross-sectional studies was used in the quantitative analysis mainly to estimate the pooled prevalence. Pooled prevalence estimates of T. vivax in domestic buffalo, cattle, dog, dromedary camel, equine, pig, small ruminant and wild animals were 30.6%, 6.4%, 2.6%, 8.4%, 3.7%, 5.5%, 3.8% and 12.9%, respectively. Stratified according to the diagnostic method, the highest pooled prevalences were found with serological techniques in domesticated buffalo (57.6%) followed by equine (50.0%) and wild animals (49.3%).

CONCLUSION

The study provides a comprehensive dataset on the geographical distribution and host range of T. vivax and demonstrates the potential of this parasite to invade other countries out of Africa and Latin America.

Parasitological and molecular detection of Trypanosoma spp. in cattle, goats and sheep in Somalia

African animal trypanosomiasis (AAT) affects the livestock of 12.3 million Somalis and constrains their development and wellbeing. There is missing data on AAT in the country after the civil war of the 1990s. Therefore, this study has aimed to assess the prevalence of Trypanosoma spp. in 614 blood samples from cattle (n = 202), goats (n = 206) and sheep (n = 206) in Afgoye and Jowhar districts, Somalia using parasitological and molecular methods. Twenty-one out of 614 (3.4%; 95% CI: 2.1-5.2%) and 101/614 (16.4%; 95% CI: 13.6-19.6%) ruminants were positive for Trypanosoma spp. by buffy coat technique (BCT) and internal transcribed spacer 1 (ITS1)-polymerase chain reaction (PCR), respectively. Using ITS1-PCR, the highest prevalence was observed in cattle (23.8%; 95% CI: 18.4-30.1%) followed by goats (17.5%; 95% CI: 12.9-23.3%) and sheep (8.3%; 95% CI: 5.1-12.9%). A total of 74/101 (73.3%; 95% CI: 63.5-81.6%) ruminants were shown coinfection with at least two Trypanosome species. The four T. brucei-positive samples have tested negative for T. b. rhodesiense, by the human-serum-resistance-associated-PCR. Trypanosoma evansi, T. godfreyi, T. vivax, T. brucei, T. simiae and T. congolense were the Trypanosoma species found in this study. This is the first study on the molecular detection of Trypanosoma sp. in ruminants in Somalia. Further investigations and control measures are needed to manage Trypanosomiasis spreading in the country. Studies should also focus on the detection of T. b. rhodesiense in the country.

Prevalence and control implications of bovine trypanosomes in endemic areas of northern Uganda

African animal trypanosomiasis (AAT), a disease complex caused by tsetse fly-transmitted Trypanosoma brucei brucei, T. congolense savannah ITS, and T. vivax, continues to inflict heavy losses to the animal industry in terms of decreased livestock production and productivity. Live bait technology and chemotherapy have been used as a control strategy in northern Uganda since 2006 with minimal success. Here, we report the results of a cross-sectional study carried out in Lango subregion, Uganda, to assess the species prevalence of bovine trypanosome in cattle using the internal transcribed spacer (ITS) of trypanosome ribosomal DNA (rDNA). Blood samples were collected from 1090 cattle by ear vein puncture and screened using a single pair of primers designed to amplify ITS ribosomal DNA (rDNA). Our results indicate an overall prevalence of 40.18% (438/1090, 95% CI 30.82-54.51). T. vivax constituted 32.66% (356/1090), T. congolense 2.39% (26/1090), T. brucei 1.28% (14/1090), T. godfreyi 0.09%(1/1090), T. brucei and T. congolense 0.36% (4/1090), T. brucei and T. vivax 1.47% (16/1090), T. vivax and T. congolense 1.65% (18/1090), T. vivax and T. simiae 0.18% (2/1090), and T. vivax and T. godfreyi 0.09% (1/1090) of infections. Over 91.7% of infections involved single species, while 9.5% were mixed infections. Over 90.2% (37/41) of the mixed infections involved T. vivax as one of the species, while 53.7% (22/41) involved T. congolense. The high prevalence of AAT and the continued presence of T. brucei raise public health concerns because of the zoonotic implications. An integrated approach that involves mass treatment of cattle, vector, and animal movement control should be adopted to reduce the risk of both AAT and HAT.

A meta-analysis of the prevalence of bovine trypanosomiasis in some African countries from 2000 to 2018

Bovine trypanosomiasis is a disease of cattle. In sub-Saharan Africa, the disease mean prevalence estimates are unknown in most endemic countries. We therefore performed a meta-analysis with the aim of estimating national mean prevalence of bovine trypanosomiasis in endemic countries across sub-Saharan Africa. Relevant articles reporting bovine trypanosomiasis prevalence were retrieved through systematic literature search and scanning of articles reference-lists. Eligibility criteria included that articles reported sample size, prevalence, and diagnostic technique adopted. Overall, data from 180 eligible articles from 19 countries satisfied the inclusion criteria. Meta-analysis of prevalence data based on the random-effects model resulted in an overall mean prevalence of 15.10% (95% CI: 13.22-17.08). National prevalence estimates were generally high except those of Benin and Senegal where estimates ranked below 10.00%. Significant heterogeneity (I² = 98.75%. p = <0.0001) was noted between studies, and univariate meta-regression analysis identified choice of diagnostic method being major contributor to observed heterogeneity (R² = 36.37%); while country of study (R² = 9.57%) and sample size (R² = 3.47%) had marginal effect on heterogeneity. In spite of past and ongoing control activities, bovine trypanosomiasis remains highly prevalent in most endemic sub-Saharan African countries. Nevertheless, dearth of epidemiological data in some countries and the use of less sensitive diagnostic tools limit reliable estimation of the disease prevalence. Therefore, there is the need to intensify efforts in aspects of surveillance and increased application of molecular diagnostic tool(s) across endemic locations as this would raise the chances of achieving a near-accurate estimate of the disease prevalence which is the first step to attempting eradication.

New insights from Gorongosa National Park and Niassa National Reserve of Mozambique increasing the genetic diversity of Trypanosoma vivax and Trypanosoma vivax-like in tsetse flies, wild ungulates and livestock from East Africa

BACKGROUND

Trypanosoma (Duttonella) vivax is a major pathogen of livestock in Africa and South America (SA), and genetic studies limited to small sampling suggest greater diversity in East Africa (EA) compared to both West Africa (WA) and SA.

METHODS

Multidimensional scaling and phylogenetic analyses of 112 sequences of the glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH) gene and 263 sequences of the internal transcribed spacer of rDNA (ITS rDNA) were performed to compare trypanosomes from tsetse flies from Gorongosa National Park and Niassa National Reserve of Mozambique (MZ), wild ungulates and livestock from EA, and livestock isolates from WA and SA.

RESULTS

Multidimensional scaling (MDS) supported Tvv (T. vivax) and TvL (T. vivax-like) evolutionary lineages: 1) Tvv comprises two main groups, TvvA/B (all SA and WA isolates plus some isolates from EA) and TvvC/D (exclusively from EA). The network revealed five ITS-genotypes within Tvv: Tvv1 (WA/EA isolates), Tvv2 (SA) and Tvv3-5 (EA). EA genotypes of Tvv ranged from highly related to largely different from WA/SA genotypes. 2) TvL comprises two gGAPDH-groups formed exclusively by EA sequences, TvLA (Tanzania/Kenya) and TvLB-D (MZ). This lineage contains more than 11 ITS-genotypes, seven forming the lineage TvL-Gorongosa that diverged from T. vivax Y486 enough to be identified as another species of the subgenus Duttonella. While gGAPDH sequences were fundamental for classification at the subgenus, major evolutionary lineages and species levels, ITS rDNA sequences permitted identification of known and novel genotypes.

CONCLUSIONS

Our results corroborate a remarkable diversity of Duttonella trypanosomes in EA, especially in wildlife conservation areas, compared to the moderate diversity in WA. Surveys in wilderness areas in WA may reveal greater diversity. Biogeographical and phylogenetic data point to EA as the place of origin, diversification and spread of Duttonella trypanosomes across Africa, providing relevant insights towards the understanding of T. vivax evolutionary history.