Genetic diversity of trypanosomes pathogenic to livestock in tsetse flies from the Nech Sar National Park in Ethiopia: A concern for tsetse suppressed area in Southern Rift Valley?

A scoping review on tsetse fly blood meal sources and its assay methods since 1956 to 2022

BACKGROUND

Tsetse flies (Glossina spp.) are the definitive biological vectors of African trypanosomes in humans and animals. Controlling this vector is the most promising method of preventing trypanosome transmission. This requires a comprehensive understanding of tsetse biology and host preference to inform targeted design and management strategies, such as the use of olfaction and visual cues in tsetse traps. No current review exists on host preference and blood meal analyses of tsetse flies.

METHODS

This review presents a meta-analysis of tsetse fly blood meal sources and the methodologies used to identify animal hosts from 1956 to August 2022. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRIMA-ScR) was applied. This focused on tsetse-endemic countries, blood meal analysis methodologies and the blood meal hosts identified. The articles were retrieved and screened from databases using predetermined eligibility criteria.

RESULTS

Only 49/393 of the articles retrieved matched the inclusion criteria. Glossina's main hosts in the wild included the bushbuck, buffalo, elephant, warthog, bushpig and hippopotamus. Pigs, livestock and humans were key hosts at the domestic interface. The least studied species included Glossina fuscipleuris, G. fusca, G. medicorum, G. tabaniformis and G. austeni. In the absence of preferred hosts, Glossina fed opportunistically on a variety of hosts. Precipitin, haemagglutination, disc diffusion, complement fixation, ELISA and PCR-based assays were used to evaluate blood meals. Cytochrome b (Cyt b) was the main target gene in PCR to identify the vertebrate hosts.

CONCLUSIONS

Tsetse blood meal sources have likely expanded because of ecological changes that could have rendered preferred hosts unavailable. The major approaches for analysing tsetse fly blood meal hosts targeted Cyt b gene for species identification by Sanger sequencing. However, small-fragment DNAs, such as the mammalian 12S and 16S rRNA genes, along with second- and third-generation sequencing techniques, could increase sensitivity for host identification in multiple host feeders that Sanger sequencing may misidentify as "noise". This review of tsetse fly blood meal sources and approaches to host identification could inform strategies for tsetse control.

Seasonal variation in tsetse fly apparent density and Trypanosoma spp. infection rate and occurrence of drug-resistant trypanosomes in Lambwe, Kenya

Tsetse flies are major arthropod vectors of trypanosomes that cause debilitating African animal trypanosomiasis. The emergence of drug-resistant trypanosomes is a common problem in sub-Saharan Africa. This study aimed to identify tsetse flies' seasonal variation in apparent densities and their infection rates and the occurrence of drug-resistant trypanosomes. Tsetse flies were collected from Lambwe, Kenya, during May and September 2021. Genomic DNA was extracted from them, and the ITS1 gene was amplified to detect Trypanosoma infection with subsequent species determination. Transporter genes DMT, E6M6, TbAT/P2, and TcoAde2 were targeted to detect polymorphisms associated with drug-resistance, using sequencing and comparison to drug-sensitive trypanosome species referenced in Genbank. A total of 498 tsetse flies and 29 non-tsetse flies were collected. The apparent density of flies was higher in wet season 6.2 fly per trap per density (FTD) than in the dry season 2.3 FTD (P = 0.001), with n = 386 and n = 141 flies caught in each season, respectively. Male tsetse flies (n = 311) were more numerous than females (n = 187) (P = 0.001). Non-tsetse flies included Tabanids and Stomoxys spp. Overall, Trypanosoma infection rate in tsetse was 5% (25/498) whereby Trypanosoma vivax was 4% (11/25), Trypanosoma congolense 36% (9/25), and Trypanosoma brucei 20% (5/25) (P = 0.186 for the distribution of the species), with infections being higher in females (P = 0.019) and during the wet season (P < 0.001). Numerous polymorphisms and insertions associated with drug resistance were detected in DMT and E6M6 genes in two T. congolense isolates while some isolates lacked these genes. T. brucei lacked TbAT/P2 genes. TcoAde2 sequences in three T. congolense isolates were related to those observed in trypanosomes from cattle blood in our previous study, supporting tsetse fly involvement in transmission in the region. We report Trypanosoma associated with trypanocidal drug-resistance in tsetse flies from Lambwe, Kenya. Female tsetse flies harbored more Trypanosoma infections than males. Tsetse transmission of trypanosomes is common in Lambwe. Risk of trypanosome infection would seem higher in the wet season, when tsetse flies and Trypanosoma infections are more prevalent than during the dry season. More efforts to control animal trypanosome vectors in the region are needed, with particular focus on wet seasons.

Trypanosomes infection, endosymbionts, and host preferences in tsetse flies (Glossina spp.) collected from Akagera park region, Rwanda: A correlational xenomonitoring study

Akagera National Park and its surroundings are home to tsetse flies and a number of their mammalian hosts in Rwanda. A One-health approach is being used in the control and surveillance of both animal and human trypanosomosis in Rwanda. Determination of the infection level in tsetse flies, species of trypanosomes circulating in vectors, the source of tsetse blood meal and endosymbionts is crucial in understanding the epidemiology of the disease in animals and humans in the region. Tsetse flies (n = 1101), comprising Glossina pallidipes (n = 771) and Glossina morsitans centralis (n = 330) were collected from Akagera park and surrounding areas between May 2018 and June 2019. The flies were screened for trypanosomes, vertebrate host DNA to identify sources of blood meal, and endosymbionts by PCR - High Resolution Melting analysis and amplicon sequencing. The feeding frequency and the feeding indices (selection index - W) were calculated to identify the preferred hosts. An overall trypanosome infection rate of 13.9% in the fly's Head and Proboscis (HP) and 24.3% in the Thorax and Abdomen (TA) were found. Eight trypanosome species were identified in the tsetse fly HP and TA, namely: Trypanosoma (T.) brucei brucei, T. congolense Kilifi, T. congolense savannah, T. vivax, T. simiae, T. evansi, T. godfreyi, T. grayi and T. theileri. We found no evidence of human-infective T. brucei rhodesiense. We also identified eighteen species of vertebrate hosts that tsetse flies fed on, and the most frequent one was the buffalo (Syncerus caffer) (36.5%). The frequently detected host by selection index was the rhinoceros (Diceros bicornis) (W = 16.2). Most trypanosome infections in tsetse flies were associated with the buffalo blood meal. The prevalence of tsetse endosymbionts Sodalis and Wolbachia was 2.8% and 4.8%, respectively. No Spiroplasma and Salivary Gland Hypertrophy Virus were detected. These findings implicate the buffaloes as the important reservoirs of tsetse-transmitted trypanosomes in the area. This contributes to predicting the main cryptic reservoirs and therefore guiding the effective control of the disease. The study findings provide the key scientific information that supports the current One Health collaboration in the control and surveillance of tsetse-transmitted trypanosomosis in Rwanda.

Trypanosoma Congolense Resistant to Trypanocidal Drugs Homidium and Diminazene and their Molecular Characterization in Lambwe, Kenya

PURPOSE

African animal trypanosomiasis (AAT) is a disease affecting livestock in sub-Saharan Africa. The use of trypanocidal agents is common practice to control AAT. This study aimed to identify drug-resistant Trypanosoma congolense in Lambwe, Kenya, and assess if molecular test backed with mice tests is reliable in detecting drug sensitivity.

METHODS

Blood samples were collected from cattle, in Lambwe, subjected to buffy coat extraction and Trypanosoma spp. detected under a microscope. Field and archived isolates were subjected to molecular characterization. Species-specific T. congolense and TcoAde2 genes were amplified using PCR to detect polymorphisms. Phylogenetic analysis were performed. Four T. congolense isolates were evaluated individually in 24 test mice per isolate. Test mice were then grouped (n=6) per treatement with diminazene, homidium, isometamidium, and controls. Mice were subsequently assessed for packed cell volume (PCV) and relapses using microscopy.

RESULTS

Of 454 samples, microscopy detected 11 T. congolense spp, eight had TcoAde2 gene, six showed polymorphisms in molecular assay. Phylogenetic analysis grouped isolates into five. Two archived isolates were homidium resistant, one was also diminazene resistant in mice. Two additional isolates were sensitive to all the drugs. Interestingly, one sensitive isolate lacked polymorphisms, while the second lacked TcoAde2, indicating the gene is not involved in drug sensitivity. Decline in PCV was pronounced in relapsed isolates.

CONCLUSION

T. congolense associated with homidium and diminazene resistance exist in Lambwe. The impact can be their spread and AAT increase. Polymorphisms are present in Lambwe strains. TcoAde2 is unlikely involved in drug sensitivity. Molecular combined with mice tests is reliable drug sensitivity test and can be applied to other genes. Decline in PCV in infected-treated host could suggest drug resistance.

Prevalence and Association of Trypanosomes and Sodalis glossinidius in Tsetse Flies from the Kafue National Park in Zambia

Tsetse flies are obligate hematophagous vectors of animal and human African trypanosomosis. They cyclically transmit pathogenic Trypanosoma species. The endosymbiont Sodalis glossinidius is suggested to play a role in facilitating the susceptibility of tsetse flies to trypanosome infections. Therefore, this study was aimed at determining the prevalence of S. glossinidius and trypanosomes circulating in tsetse flies and checking whether an association exists between trypanosomes and Sodalis infections in tsetse flies from Kafue National Park in Zambia. A total of 326 tsetse flies were sampled from the Chunga and Ngoma areas of the national park. After DNA extraction was conducted, the presence of S. glossinidius and trypanosome DNA was checked using PCR. The Chi-square test was carried out to determine whether there was an association between the presence of S. glossinidius and trypanosome infections. Out of the total tsetse flies collected, the prevalence of S. glossinidius and trypanosomes was 21.8% and 19.3%, respectively. The prevalence of S. glossinidius was 22.2% in Glossina morsitans and 19.6% in Glossina pallidipes. In relation to sampling sites, the prevalence of S. glossinidius was 26.0% in Chunga and 21.0% in Ngoma. DNA of trypanosomes was detected in 18.9% of G. morsitans and 21.4% of G. pallidipes. The prevalence of trypanosomes was 21.7% and 6.0% for Ngoma and Chunga, respectively. The prevalences of trypanosome species detected in this study were 6.4%, 4.6%, 4.0%, 3.7%, 3.1%, and 2.5% for T. vivax, T. simiae, T. congolense, T. godfreyi, T. simiae Tsavo, and T. b. brucei, respectively. Out of 63 trypanosome infected tsetse flies, 47.6% of the flies also carried S. glossinidius, and the remaining flies were devoid of S. glossinidius. A statistically significant association was found between S. glossinidius and trypanosomes (p < 0.001) infections in tsetse flies. Our findings indicated that presence of S. glossinidius increases the susceptibility of tsetse flies to trypanosome infections and S. glossinidius could be a potential candidate for symbiont-mediated vector control in these tsetse species.

Evaluating the efficacy of various traps in catching tsetse flies at Nech Sar and Maze National Parks, Southwestern Ethiopia: An Implication for Trypanosoma Vector Control

Tsetse flies are the vector of protozoan parasite of the genus Trypanosoma, the causative agent of human African sleeping sickness and animal trypanosomiasis. Traps such as Nguruman (NGU), biconical and sticky traps are in use for tsetse flies sampling and monitoring. However, there is no evidence regarding their comparative efficiency in catching flies using olfactory cues. Therefore, the present study aimed to evaluate the efficiency of different types of traps in catching tsetse flies at Nech Sar and Maze National Parks, Southwestern Ethiopia. The study was done for six consecutive months from February to July 2019. Briefly, a 3×4 Latin square design was performed, and tsetse flies were collected for three days each month in four different vegetation types, including wood grassland, bush land, forest, and riverine forest. To avoid trapping position bias, rotation of traps has been done every day. Almost all (99.5%) of the flies were Glossina pallidipes and the remaining were G. fuscipes. The latter were present only at Maze national park. NGU traps were the most efficient type with 12.1 flies/trap/day at Nech Sar National Park and it was 2.2 flies/trap/day at Maze National Park followed by biconical and sticky traps. The number of tsetse flies collected by biconical trap was three-fold lower than NGU trap, and it was four-fold lower in sticky trap than NGU trap in both Nech Sar and Maze National Parks. A substantial number (41%) of G. pallidipes were collected from woody grassland (WGL). In conclusion, G. pallidipes monitoring and evaluation activities could consider NGU trap model as it performed better in most vegetation types in the region.

Glossina pallidipes Density and Trypanosome Infection Rate in Arba Minch Zuria District of Gamo Zone, Southern Ethiopia

Background

African trypanosomosis is a disease of both animals and humans resulting from infection with parasitaemic protozoa of the genus Trypanosoma transmitted mainly by the tsetse flies (Glossina species). The disease has been reported in different parts of the country. However, information on the apparent density and trypanosome infection rates of the vectors is very limited in the Southern part of Ethiopia. Therefore, this study was conducted to estimate the apparent density, infection rate of trypanosomes in Glossina pallidipes, and the trypanosome species involved in Arba Minch Zuria district of Southern Ethiopia.

Methods

A cross-sectional study was conducted from January to June 2018 in two purposely selected kebeles of Arbaminch Zuria district and in the escarpments of Nech Sar National Park of Southern Ethiopia. For entomological survey, a total of 40 standard NGU traps were deployed around the watering and grazing areas. A total of 300 fresh Glossina pallidipes were examined for trypanosome infection using a dissection procedure as described by the FAO Training manual for tsetse control personnel.

Results

The study revealed the presence of only one Glossina species, known as Glossina pallidipes, and biting flies including Stomoxys and Tabanus. A total of 2176 flies were caught of which 1803 (82.86%) belong to Glossina pallidipes and the remaining 373 (17.14%) were biting flies. The overall apparent density of Glossina pallidipes and biting flies in the study area were 15.03 fly/trap/day (F/T/D) and 3.11 F/T/D, respectively. Relatively higher Glossina pallidipes and biting flies, respectively, were caught in a wood-grass land (15.87 F/T/D and 3.69 F/T/D) and riverine forest (15.13 F/T/D and 3.42 F/T/D) than bush land vegetation types (13.87 F/T/D and 1.76 F/T/D). The overall trypanosome infection rate of Glossina pallidipes was 17.67% (53/300). Two trypanosome species, namely, Trypanosoma congolense (66.04%) and Trypanosoma vivax (33.96%), were responsible for Glossina pallidipes infection in the study area. Trypanosome infection rate was significantly higher in female G. pallidipes than in male (OR = 3.39, 95%CI = 1.53‐7.52). Significantly, higher trypanosome infection rate was observed in flies older than 20 days (OR = 2.5, 95%CI = 1.12‐5.56) and in hunger stage 1 flies (OR = 14.24, 95%CI = 4.01‐50.59). Glossina pallidipes infection was significantly higher in and around park grazing areas (OR = 3.41, 95%CI = 1.76‐6.6) and wood-grass land vegetation type (OR = 2.7, 95%CI = 1.2‐6.5).

Conclusion

The current study revealed high apparent density and trypanosome infection in Glossina pallidipes in Arba Minch Zuria district of Southern Ethiopia. So, this study warrants the need for strengthening both vector and parasite control strategies in the study area.

Molecular Identification of Trypanosome Diversity in Domestic Animals Reveals the Presence of Trypanosoma brucei gambiense in Historical Foci of Human African Trypanosomiasis in Gabon

Human African Trypanosomiasis (HAT) is an infectious disease caused by protozoan parasites belonging to the Trypanosoma genus. In sub-Saharan Africa, there is a significant threat as many people are at risk of infection. Despite this, HAT is classified as a neglected tropical disease. Over the last few years, several studies have reported the existence of a wide diversity of trypanosome species circulating in African animals. Thus, domestic and wild animals could be reservoirs of potentially dangerous trypanosomes for human populations. However, very little is known about the role of domestic animals in maintaining the transmission cycle of human trypanosomes in central Africa, especially in Gabon, where serious cases of infection are recorded each year, sometimes leading to hospitalization or death of patients. Komo-Mondah, located within Estuaries (Gabonese province), stays the most active HAT disease focus in Gabon, with a mean of 20 cases per year. In this study, we evaluated the diversity and prevalence of trypanosomes circulating in domestic animals using the Polymerase Chain Reaction (PCR) technique. We found that 19.34% (53/274) of the domestic animals we studied were infected with trypanosomes. The infection rates varied among taxa, with 23.21% (13/56) of dogs, 16.10% (19/118) of goats, and 21.00% (21/100) of sheep infected. In addition, we have observed a global mixed rate of infections of 20.75% (11/53) among infected individuals. Molecular analyses revealed that at least six Trypanosome species circulate in domestic animals in Gabon (T. congolense, T. simiae, T. simiae Tsavo, T. theileri, T. vivax, T. brucei (including T. brucei brucei, and T. brucei gambiense)). In conclusion, our study showed that domestic animals constitute important potential reservoirs for trypanosome parasites, including T. brucei gambiense, which is responsible for HAT.

Metabolites From Trypanosome-Infected Cattle as Sensitive Biomarkers for Animal Trypanosomosis

Trypanosomes are important global livestock and human pathogens of public health importance. Elucidating the chemical mechanisms of trypanosome-relevant host interactions can enhance the design and development of a novel, next-generation trypanosomosis diagnostics. However, it is unknown how trypanosome infection affects livestock volatile odors. Here, we show that Trypanosoma congolense and Trypanosoma vivax infections induced dihydro-β- ionone and junenol, while abundance of dihydro-α-ionone, phenolics, p-cresol, and 3-propylphenol significantly elevated in cow urine. These biomarkers of trypanosome infection are conserved in cow breath and the urine metabolites of naturally infected cows, regardless of population, diet, or environment differences. Furthermore, treating trypanosome-infected cows reduced the levels of these indicators back to the pre-infection levels. Finally, we demonstrated that the potential of some specific biomarkers of phenolic origin may be used to detect active trypanosome infections, including low-level infections that are not detectable by microscopy. The sensitivity and specificity of biomarkers detection are suited for rapid, robust, and non-invasive trypanosomosis diagnosis under field conditions.

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%.

Parasites and blood-meal hosts of the tsetse fly in Tanzania: a metagenomics study

Background

Tsetse flies can transmit various Trypanosoma spp. that cause trypanosomiasis in humans, wild animals, and domestic animals. Amplicon deep sequencing of the 12S ribosomal RNA (rRNA) gene can be used to detect mammalian tsetse hosts, and the 18S rRNA gene can be used to detect all associated eukaryotic pathogens, including Trypanosoma spp.

Methods

Tsetse flies were collected from the Serengeti National Park (n = 48), Maswa Game Reserve (n = 42), and Tarangire National Park (n = 49) in Tanzania in 2012–13. Amplicon deep sequencing targeting mammal-specific 12S rRNA and 18S rRNA genes was performed to screen the blood-feeding sources of tsetse flies and eukaryotic parasites in tsetse flies, respectively.

Results

12S rRNA gene deep sequencing revealed that various mammals were blood-feeding sources of the tsetse flies, including humans, common warthogs, African buffalos, mice, giraffes, African elephants, waterbucks, and lions. Genes of humans were less frequently detected in Serengeti (P = 0.0024), whereas African buffaloes were detected more frequently as a blood-feeding source (P = 0.0010). 18S rRNA gene deep sequencing showed that six tsetse samples harbored the Trypanosoma gene, which was identified as Trypanosoma godfreyi and Trypanosoma simiae in subsequent ITS1 gene sequencing.

Conclusions

Through amplicon deep sequencing targeting the 12S rRNA and 18S rRNA genes, various mammalian animals were identified as blood-meal sources, and two Trypanosoma species were detected in tsetse flies collected from the Maswa Game Reserve, Serengeti National Park, and Tarangire National Park in Tanzania. This study illustrates the patterns of parasitism of tsetse fly, wild animals targeted by the fly, and Trypanosoma spp. carried by the fly in Tanzania. It may provide essential data for formulating better strategies to control African trypanosomes.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05344-1.

A novel metabarcoded deep amplicon sequencing tool for disease surveillance and determining the species composition of Trypanosoma in cattle and other farm animals

The World Health Organization (WHO) and the Food and Agriculture Organization (FAO) have developed strategies to control trypanosomiasis in humans and livestock in endemic areas. These require a better understanding of the distribution of different Trypanosoma species and improved predictions of where they might appear in the future, based on accurate diagnosis and robust surveillance systems. Here, we describe a metabarcoding deep amplicon sequencing method to identify and determine the Trypanosoma species in co-infecting communities. First, four morphological verified Trypanosoma species (T. brucei, T. congolense, T. vivax and T. theileri) were used to prepare test DNA pools derived from different numbers of parasites to evaluate the method's detection threshold for each of the four species and to assess the accuracy of their proportional quantification. Having demonstrated the accurate determination of species composition in Trypanosoma communities, the method was applied to determine its detection threshold using blood samples collected from cattle with confirmed Trypanosoma infections based on a PCR assay. Each sample showed a different Trypanosoma species composition based on the proportion of MiSeq reads. Finally, we applied the assay to field samples to develop new insight into the species composition of Trypanosoma communities in cattle, camels, buffalo, horses, sheep, and goat in endemically infected regions of Pakistan. We confirmed that Trypanosoma evansi is the major species in Pakistan and for the first time showed the presence of Trypanosoma theileri. The metabarcoding deep amplicon sequencing method and bioinformatics pathway have several potential applications in animal and human research, including evaluation of drug treatment responses, understanding of the emergence and spread of drug resistance, and description of species interactions during co-infections and determination of host and geographic distribution of trypanosomiasis in humans and livestock.

Seasonal Patterns: Bovine Trypanosomosis, Glossina pallidipes Density, and Infection in Rift Valleys of Gamo Zone, Southern Ethiopia

Bovine trypanosomosis is a parasitic disease causing serious economic losses in livestock productivity and agricultural development. The disease has been reported in different parts of Ethiopia. However, seasonal pattern of trypanosomosis, tsetse fly apparent density, and infection are very limited in the southern rift valley of the country, particularly in Gamo Zone. Therefore, the objective of this cross-sectional study design was to estimate seasonal prevalence of bovine trypanosomosis, assessing tsetse fly apparent density and its infection by trypanosomes. For the parasitological study, a total of 600 cattle (300 in each season) were sampled and assayed using the buffy coat technique. A total of 80 standard NGU traps were deployed around the watering and grazing areas for the entomological survey. An overall prevalence of trypanosomosis was 10.17% (61/600), of which 7.33% (22/300) and 13% (39/300) accounted for the dry and wet seasons, respectively. The prevalence of trypanosomosis was significantly higher during the wet season (OR = 2.47; p < 0.05), in black coat color (OR = 7.2, p < 0.05), and poor body-conditioned (OR = 3.15; p < 0.05) animals. Two species of trypanosomes, Trypanosoma congolense, 68.85% (42/61), and Trypanosoma vivax, 31.15% (19/61), were circulating in the area. The mean PCV value in infected animals (22.56 ± 4.61) was significantly lower than in non-infected animals (25.3 ± 4.75). Entomological result indicated that Glossina pallidipes (G. pallidipes) was the only species of tsetse found in the study area. Totally, 3,789 flies were caught of which 81.42% (3,085/3,789) belong to G. pallidipes and 18.58% (704/3,789) were other biting flies. The overall apparent density of G. pallidipes was 12.85 flies/trap/day (FTD). Relatively higher G. pallidipes/trap/day were caught in the wet season (13.64 F/T/D) than in the dry season (12.07F/T/D). Of the flies caught, 342 G. pallidipes were randomly selected and dissected. The overall proportion of G. pallidipes infection was 18.42% (63/342) of which 12.28% (21/171) and 24.56% (42/171) were accounted in the dry and wet seasons, respectively. Infection in G. pallidipes was significantly higher during the wet season (OR = 2.32; p < 0.05) and in park grazing areas (OR = 2.45; p < 0.05). In conclusion, trypanosomosis is the major challenge for cattle productivity in the district. So this study warrants the need for strengthening the vector and parasite control interventions in the area.

High Trypanosoma vivax infection rates in water buffalo and cattle in the Brazilian Lower Amazon

Highly sensitive and accurate molecular diagnostic methods have not yet been employed for livestock trypanosomosis in the Brazilian Lower Amazon although the first reports of Trypanosoma vivax and Trypanosoma evansi in Brazil were in water buffalo (Bubalus bubalis) in this region. The present study assessed trypanosomosis in buffalo and cattle raised in communal and seasonally flooding pastures in the state of Pará using the fluorescent fragment length barcoding (FFLB) method. T. evansi was not detected, but high infection rates of T. vivax and T. theileri were revealed by a simplified FFLB standardized in the present study that discriminates all trypanosome species infective to livestock in South America. T. vivax infection rates detected by TviCATL-PCR were 24.6% for cattle (n = 61) and 28.1% for buffalo (n = 89). Using the FFLB method, overall T. vivax infection rates increased to 59.6% and 44.3% for buffalo and cattle, respectively. Furthermore, the predominance of a single microsatellite-based genotype of T. vivax was reinforced in the Lower Amazon. Relevant T. vivax infection rates detected in clinically healthy buffalo and cattle through the sampled years (2008-2017) highlight the need for systematic studies to demonstrate the endemic steady state of T. vivax in this region. Our findings provide baseline information for livestock management, including control of T. vivax dispersal, and the introduction of naïve animals. The growing international trade of live livestock from this very important livestock breeding region represents a serious risk for T. vivax spreading outside Amazonia and Brazil.

Expanding our knowledge on African trypanosomes of the subgenus Pycnomonas: A novel Trypanosoma suis-like in tsetse flies, livestock and wild ruminants sympatric with Trypanosoma suis in Mozambique

Among the subgenera of African tsetse-transmitted trypanosomes pathogenic to livestock, the least known is the subgenus Pycnomonas, which contains a single species, Trypanosoma suis (TSU), a pathogen of domestic pigs first reported in 1905 and recently rediscovered in Tanzania and Mozambique. Analysis by Fluorescent Fragment Length Barcoding (FFLB) revealed an infection rate of 20.3% (108 out of 530 tsetse flies) in a recent study in the Gorongosa and Niassa wildlife reserves in Mozambique, and demonstrated two groups of Pycnomonas trypanosomes: one (14.1%, 75 flies) showing an FFLB profile identical to the reference TSU from Tanzania, and the other (6.2%, 33 flies) differing slightly from reference TSU and designated Trypanosoma suis-like (TSU-L). Phylogenetic analyses tightly clustered TSU and TSU-L from Mozambique with TSU from Tanzania forming the clade Pycnomonas positioned between the subgenera Trypanozoon and Nannomonas. Our preliminarily exploration of host ranges of Pycnomonas trypanosomes revealed TSU exclusively in warthogs while TSU-L was identified, for the first time for a member of the subgenus Pycnomonas, in ruminants (antelopes, Cape buffalo, and in domestic cattle and goats). The preferential blood meal sources of tsetse flies harbouring TSU and TSU-L were wild suids, and most of these flies concomitantly harboured the porcine trypanosomes T. simiae, T. simiae Tsavo, and T. godfreyi. Therefore, our findings support the link of TSU with suids while TSU-L remains to be comprehensively investigated in these hosts. Our results greatly expand our knowledge of the diversity, hosts, vectors, and epidemiology of Pycnomonas trypanosomes. Due to shortcomings of available molecular diagnostic methods, a relevant cohort of trypanosomes transmitted by tsetse flies to ungulates, especially suids, has been neglected or most likely misidentified. The method employed in the present study enables an accurate discrimination of trypanosome species and genotypes and, hence, a re-evaluation of the "lost" subgenus Pycnomonas and of porcine trypanosomes in general, the most neglected group of African trypanosomes pathogenic to ungulates.