New epidemiological features on animal trypanosomiasis by molecular analysis in the pastoral zone of Sideradougou, Burkina Faso

A multidisciplinary work was undertaken in the agropastoral zone of Sidéradougou, Burkina Faso to try to elucidate the key factors determining the presence of tsetse flies. In this study the PCR was used to characterize trypanosomes infecting the vector ( Glossina tachinoides and Glossina palpalis gambiensis ) and the host, i.e. cattle. A 2-year survey involved dissecting 2211 tsetse of the two Glossina species. A total of 298 parasitologically infected tsetse were analysed by PCR. Trypanosoma vivax was the most frequently identified trypanosome followed by the savannah type of T. congolense and, to a lesser extent, the riverine forest type of T. congolense , and by T. brucei . No cases of T. simiae were found. From the 107 identified infections in cattle, the taxa were the same, but T. congolense savannah type was more frequent, whereas T. vivax and T. congolense riverine forest types were found less frequently. A correlation was found between midgut infection rates of tsetse, nonidentified infections and reptile bloodmeals. These rates were higher in G.p. gambiensis , and in the western part of the study area. T. vivax infections were related to cattle bloodmeals, and were more frequent in G. tachinoides and in the eastern study area. The PCR results combined with bloodmeal analysis helped us to establish the relationships between the vector and the host, to assess the trypanosome challenge in the two parts of the area, to elucidate the differences between the two types of T. congolense , and to suspect that most midgut infections were originating from reptilian trypanosomes.     

Does isometamidium chloride treatment protect tsetse flies from trypanosome infections during SIT campaigns?

African animal trypanosomosis is a major pathological constraint to cattle breeding across 10 million km2 of sub-Saharan West African countries infested by tsetse flies, their cyclic vectors. The release of sterile males (sterile insect technique [SIT]) is a potentially important control technique aimed at eliminating the vectors. Prior to release, tsetse are generally treated with isometamidium chloride, a trypanocide, to prevent them from transmitting parasites. The present study investigated the preventive action of isometamidium chloride (0.5 mg/L) on the subsequent susceptibility of tsetse released into the wild. A total of 1755 Glossina palpalis gambiensis Vanderplank and 744 Glossina tachinoides Westwood were released, of which 50 and 48, respectively, were recaptured 22-43 days after release. Their probosces were analysed by polymerase chain reaction to identify mature infections with three trypanosome species (Trypanosoma vivax, Trypanosoma brucei sensu lato and Trypanosoma congolense savannah type). Two mature infections with T. vivax and four with T. congolense were detected, indicating that the use of this treatment regimen in an SIT campaign would not totally prevent sterile males from transmitting trypanosomes.     

Feeding behaviour of Glossina pallidipes and g. morsitans centralis on Boran cattle infected with trypanosoma congolense or T. vivax under laboratory conditions

In field studies, tsetse flies (Diptera: Glossinidae) feed more successfully on cattle infected with Trypanosoma congolense Broden (Kinetoplastida: Trypanosomatidae) than on cattle infected with T. vivax Ziemann or uninfected cattle. Here we describe the first laboratory investigation of this phenomenon. In the first experiment, caged Glossina pallidipes Austen were fed for 1 and 5 min on a Boran steer infected with T. congolense clone IL 1180 and on an uninfected steer. Feeding success was recorded in this way five times over several weeks. The same protocol was subsequently used in three additional experiments with the following combinations: G. pallidipes and a steer infected with T. vivax stock IL 3913, G. morsitans centralis Machado and a steer infected with T. congolense, and G. morsitans centralis and a steer infected with T. vivax. The four experiments were replicated once, making eight experiments in total. In three experiments there was increased tsetse feeding success, measured at 1 min, after a steer became infected (T. congolense, two experiments and T. vivax, one experiment). Analysis of all data combined found no significant differences in tsetse feeding success on the different groups of cattle prior to infection, but after infection tsetse feeding success was significantly greater on the infected cattle (P< 0.001). Trypanosoma congolense infection led to a greater increase in tsetse feeding success than T. vivax infection. The increase in feeding success was not related to changes in the level of anaemia, skin surface temperature or parasitaemia. A possible explanation is the effects of trypanosome infection on cutaneous vasodilation and/or blood clotting in infected cattle. When allowed to feed for 5 min, nearly all tsetse engorged successfully and effects of cattle infection on feeding success were not found.     

Suppressive action of Samorin on the cyclical development of pathogenic trypanosomes in Glossina morsitans centralis

Male Glossina sexually sterilized by gamma-irradiation are as efficient vectors of trypanosomiasis as fertile males. An attempt was made, using isometamidium chloride (Samorin), to interfere with the cyclical development of trypanosomes in sterile males, destined for use in the sterile insect release (SIR) method of tsetse eradication. The infection rate with mature Trypanosoma congolense Broden was effectively reduced in sterile male Glossina morsitans centralis Machado, when the flies were fed on an infected goat 2 days after they were fed as tenerals on an in vitro bloodmeal containing 8 micrograms Samorin/ml blood. The infection rates with mature T.vivax Ziemann and T.brucei brucei Plimmer & Bradford were completely suppressed at this drug dose. Whensterile teneral males were fed on a bloodmeal containing 12 micrograms/ml Samorin and given the infected bloodmeal 10 days later, infections by mature T.vivax, T.congolense and T.b.brucei were completely suppressed. Hence in the management of a tsetse eradication programme utilizing the SIR method, it is recommended that the sterile teneral male tsetse should, prior to release, be given a bloodmeal containing Samorin at 12-15 micrograms/ml blood. This will effectively suppress future disease transmission.     

Climate,Cattle Rearing Systems and African Animal Trypanosomosis Risk in Burkina Faso

Background

In sub-Saharan countries infested by tsetse flies, African Animal Trypanosomosis (AAT) is considered as the main pathological constraint to cattle breeding. Africa has known a strong climatic change and its population was multiplied by four during the last half-century. The aim of this study was to characterize the impact of production practices and climate on tsetse occurrence and abundance, and the associated prevalence of AAT in Burkina Faso.

Methodology/Principal Findings

Four sites were selected along a South-north transect of increasing aridity. The study combines parasitological and entomological surveys. For the parasitological aspect, blood samples were collected from 1,041 cattle selected through a stratified sampling procedure including location and livestock management system (long transhumance, short transhumance, sedentary). Parasitological and serological prevalence specific to livestock management systems show a gradual increase from the Sahelian to the Sudano-Guinean area (P<0.05). Livestock management system had also a significant impact on parasitological prevalence (P<0.05). Tsetse diversity, apparent densities and their infection rates overall decreased with aridity, from four species, an apparent density of 53.1 flies/trap/day and an infection rate of 13.7% to an absence at the northern edge of the transect, where the density and diversity of other biting flies were on the contrary highest (p<0.001).

Conclusions/Significance

The climatic pressure clearly had a negative impact on tsetse abundance and AAT risk. However, the persistency of tsetse habitats along the Mouhoun river loop maintains a high risk of cyclical transmission of T. vivax. Moreover, an “epidemic mechanical livestock trypanosomosis” cycle is likely to occur in the northern site, where trypanosomes are brought in by cattle transhuming from the tsetse infested area and are locally transmitted by mechanical vectors. In Burkina Faso, the impact of tsetse thus extends to a buffer area around their distribution belt, corresponding to the herd transhumance radius.     

Experimental evaluation of xenodiagnosis to detect trypanosomes at low parasitaemia levels in infected hosts

In Human African Trypanosomosis (HAT) endemic areas, there are a number of subjects that are positive to serological tests but in whom trypanosomes are difficult to detect with the available parasitological tests. In most cases and particularly in West Africa, these subjects remain untreated, thus posing a fundamental problem both at the individual level (because of a possible lethal evolution of the disease) and at the epidemiological level (since they are potential reservoirs of trypanosomes). Xenodiagnosis may constitute an alternative for this type of cases. The objective of this study was to update the use of xenodiagnosis to detect trypanosomes in infected host characterized by low parasitaemia levels. This was carried out experimentally by infecting cattle and pigs with Trypanosoma congolense and T. brucei gambiense respectively, and by feeding tsetse flies (Glossina morsitans submorsitans and G. palpalis gambiensis, from the CIRDES colonies) on these animals at a time when the observed blood parasitaemia were low or undetectable by the classical microscopic parasitological tests used for the monitoring of infected animals. Our results showed that: i) the G. p. gambiensis colony at CIRDES could not be infected with the T. b. gambiense stocks used; ii) midgut infections of G. m. submorsitans were observed with both T. congolense and T. b. gambiense; iii) xenodiagnosis remains positive even at very low blood parasitaemia for both T. congolense and T. b. gambiense; and iv) to implement T. b. gambiense xenodiagnosis, batches of 20 G. m. submorsitans should be dissected two days after the infective meal. These results constitute a first step toward a possible implementation of xenodiagnosis to better characterize the parasitological status of seropositive individuals and the modalities of parasite transmission in HAT foci.     

Control of Glossina longipennis (Diptera: Glossinidae) by insecticide-treated targets at Galana ranch, Kenya, and confirmation of the role of G. longipennis as a vector of cattle trypanosomiasis

Glossina longipennis Corti was studied in Galana Ranch, Kenya over a four year period, in two areas (Tank E and Lali) where the species was abundant and other species were absent or scarce. There was active transmission of trypanosomiasis to cattle in both areas, the parasite species being Trypanosoma vivax Ziemann and T. congolense Broden. Mean infection rates of the G. longipennis were 1.1% and 0. 55% for T. vivax and T. congolense respectively at Tank E, and 0.88% and 0.15% at Lali. Experimental transmission studies showed that cattle in fly-proof enclosures challenged with wild G. longipennis collected from Galana became infected with both trypanosome species. A tsetse control operation in one area (Tank E) using targets impregnated with deltamethrin in an oil formulation reduced the population of G. longipennis by 98% over one year, despite evidence of re-invasion. Populations of G. longipennis in the other area (Lali) were relatively stable over the whole study period. The effect of tsetse control on the incidence of cattle trypanosomiasis at Tank E was less clear than that on tsetse numbers, probably due to the lack of a sustained reduction in tsetse numbers. However, a significant relationship was demonstrated between fortnightly incidence measurements and electric net catches of G. longipennis at Tank E. A further significant predictor of incidence was rainfall in the previous four to seven weeks. This study confirms the importance of G. longipennis as a vector of bovine trypanosomiasis in areas where it is the predominant tsetse present.     

Molecular cloning and characterization of Trypanosoma vivax alternative oxidase (AOX) gene, a target of the trypanocide ascofuranone

Trypanosoma vivax causes nagana disease in cattle. Since T. vivax is transmitted not only by tsetse flies but also by other biting flies (non-cyclic transmission), the parasite has been distributed to and has had a significant economic impact on wide geographical areas, including Africa and South America. Our previous study on Trypanosoma brucei brucei showed that the trypanosome alternative oxidase (TAO, TbAOX) is a promising target of chemotherapy. For this reason, we also have cloned the T vivax AOX (TvAOX) gene and characterized the recombinant enzyme. The deduced amino acid sequence (328 a.a.) of TvAOX shares 76% identity with TbAOX and contains the diiron-coordination motifs (-E-, -EXXH-) that are conserved among AOXs. The Km of recombinant TvAOX (rTvAOX) expressed in Escherichia coli for ubiquinol (87.0 +/- 0.54 microM) was significantly lower than the value for recombinant TbAOX (rTbAOX) (714 +/- 4.5 microM). Ascofuranone, the most potent inhibitor of TbAOX, was a competitive inhibitor of rTvAOX with a Ki value (0.40 +/- 0.00 nM) significantly lower than that for rTbAOX (1.29 +/- 0.00 nM). The non-cyclic transmission ability of T. vivax and the in vivo chemotherapeutic efficacy of ascofuranone against T. vivax and T. b. brucei infection are discussed in terms of these Km and Ki values.     

The effect of trypanosomosis on pregnancy in trypanotolerant Orma Boran cattle

A study was undertaken to investigate the influence of trypanosomosis on the outcome of pregnancy in trypanotolerant Orma Boran (Bos indicus) exposed to natural tsetse challenge in an area of Kenya infested predominantly with Glossina pallidipes. Of 73 pregnant Orma heifers, 58 (79.5%) produced live calves at term, 13 (17.8%) aborted and 2 (2.7%) died of trypanosomosis. Of the 71 surviving animals, 22 (31%) were infected with Trypanosoma vivax , 21 (29.6%) T. congolense, and 26 (36.6%) had mixed infections with T. vivax and T. congolense. These results suggest that in areas of high trypanosomosis risk reproductive function is affected even in trypanotolerant cattle, and that both T. vivax and T. congolense can be responsible for the abortions observed in the field. It is suggested that maintenance of pregnancy in the face of trypanosome challenge was dependent on individual variation among the Orma cattle, but as challenge increased beyond the limits of effectiveness of trypanotolerance, disruption of pregnancy occurred.     

Trypanosoma vivax, T. congolense "forest type" and T. simiae: prevalence in domestic animals of sleeping sickness foci of Cameroon

In order to better understand the epidemiology of Human and Animal trypanosomiasis that occur together in sleeping sickness foci, a study of prevalences of animal parasites (Trypanosoma vivax, T. congolense "forest type", and T. simiae) infections was conducted on domestic animals to complete the previous work carried on T. brucei gambiense prevalence using the same animal sample. 875 domestic animals, including 307 pigs, 264 goats, 267 sheep and 37 dogs were sampled in the sleeping sickness foci of Bipindi, Campo, Doumé and Fontem in Cameroon. The polymerase chain reaction (PCR) based method was used to identify these trypanosome species. A total of 237 (27.08%) domestic animals were infected by at least one trypanosome species. The prevalence of T. vivax, T. congolense "forest type" and T. simiae were 20.91%, 11.42% and 0.34% respectively. The prevalences of 7 vivax and T. congolense "forest type" differed significantly between the animal species and between the foci (p < 0.0001); however, these two trypanosomes were found in all animal species as well as in all the foci subjected to the study. The high prevalences of 7 vivax and T congolense "forest type" in Bipindi and Fontem-Center indicate their intense transmission in these foci.     

Trypanosoma vivax: mechanical transmission in cattle by one of the most common African tabanids,Atylotus agrestis

The role of mechanical vectors in the transmission of African livestock trypanosomes has always been controversial relative to tsetse flies, their cyclical vectors. An experiment was carried out in Burkina Faso to demonstrate mechanical transmission of Trypanosoma vivax by one of the most common tabanids in Africa: Atylotus agrestis. Eight heifers (crossbred zebuxBaoulé), free of trypanosome infection, were kept in a corral covered by a mosquito net, together with two heifers infected experimentally with a local stock of T. vivax. On average, 324 A. agrestis, freshly captured with Nzi traps, were introduced daily over 20 days. Parasitological, PCR and serological examinations were carried out regularly to assess infections and levels of parasitaemia. Microscopic examination of buffy-coats indicated that five of the eight receiver-heifers were infected on days 8, 13, 32, 41, and 48. PCR results indicated that these five heifers were already infected by day 13. Mechanical transmission of T. vivax by A. agrestis was demonstrated unequivocally, at a high rate (63% in 13-20 days). Conditions of transmission in this experiment are discussed in terms of natural rates of challenge. The importance of tabanids as mechanical vectors of T. vivax should be re-considered, in light of these results. Creation of tsetse free zones in Africa will generally lead to the disappearance of T. congolense, T. brucei, and most often T. vivax as well; however, in areas where T. vivax can be mechanically transmitted, clearance of tsetse may not be sufficient to eradicate livestock trypanosomosis.     

Spatio-temporal distribution of tsetse and other biting flies in the Mouhoun River basin, Burkina Faso

In the Mouhoun River basin, Burkina Faso, the main vectors of African animal trypanosomoses are Glossina palpalis gambiensis Vanderplank and Glossina tachinoides Westwood (Diptera: Glossinidae), both of which are riverine tsetse species. The aim of our study was to understand the impact of landscape anthropogenic changes on the seasonal dynamics of vectors and associated trypanosomosis risk. Three sites were selected on the basis of the level of disturbance of tsetse habitats and predominant tsetse species: disturbed (Boromo, for G. tachinoides) and half-disturbed (Douroula for G. tachinoides and Kadomba for G. p. gambiensis). At each of these sites, seasonal variations in the apparent densities of tsetse and mechanical vectors and tsetse infection rates were monitored over 17 months. Tsetse densities differed significantly between sites and seasons. Of 5613 captured tsetse, 1897 were dissected; 34 of these were found to be infected with trypanosomes. The most frequent infection was Trypanosoma vivax (1.4%), followed by Trypanosoma congolense (0.3%) and Trypanosoma brucei (0.05%). The mean physiological age of 703 tsetse females was investigated to better characterize the transmission risk. Despite the environmental changes, it appeared that tsetse lived long enough to transmit trypanosomes, especially in half-disturbed landscapes. A total of 3021 other biting flies from 15 species (mainly Tabanidae and Stomoxyinae) were also caught: their densities also differed significantly among sites and seasons. Their relative importance regarding trypanosome transmission is discussed; the trypanosomosis risk in cattle was similar at all sites despite very low tsetse densities (but high mechanical vector densities) in one of them.     

Occurrence,diversity and distribution of Trypanosoma infections in cattle around the Akagera National Park,Rwanda

BackgroundAfrican Trypanosomiases threaten the life of both humans and animals. Trypanosomes are transmitted by tsetse and other biting flies. In Rwanda, the African Animal Trypanosomiasis (AAT) endemic area is mainly around the tsetse-infested Akagera National Park (NP). The study aimed to identify Trypanosoma species circulating in cattle, their genetic diversity and distribution around the Akagera NP.MethodologyA cross-sectional study was carried out in four districts, where 1,037 cattle blood samples were collected. The presence of trypanosomes was determined by microscopy, immunological rapid test VerY Diag and PCR coupled with High-Resolution Melt (HRM) analysis. A parametric test (ANOVA) was used to compare the mean Packed cell Volume (PCV) and trypanosomes occurrence. The Cohen Kappa test was used to compare the level of agreement between the diagnostic methods.FindingsThe overall prevalence of trypanosome infections was 5.6%, 7.1% and 18.7% by thin smear, Buffy coat technique and PCR/HRM respectively. Microscopy showed a low sensitivity while a low specificity was shown by the rapid test (VerY Diag). Trypanosoma (T.) congolense was found at a prevalence of 10.7%, T. vivax 5.2%, T. brucei brucei 2% and T. evansi 0.7% by PCR/HRM. This is the first report of T.evansi in cattle in Rwanda. The non-pathogenic T. theileri was also detected. Lower trypanosome infections were observed in Ankole x Friesian breeds than indigenous Ankole. No human-infective T. brucei rhodesiense was detected. There was no significant difference between the mean PCV of infected and non-infected animals (p>0.162).ConclusionsOur study sheds light on the species of animal infective trypanosomes around the Akagera NP, including both pathogenic and non-pathogenic trypanosomes. The PCV estimation is not always an indication of trypanosome infection and the mechanical transmission should not be overlooked. The study confirms that the area around the Akagera NP is affected by AAT, and should, therefore, be targeted by the control activities. AAT impact assessment on cattle production and information on the use of trypanocides are needed to help policymakers prioritise target areas and optimize intervention strategies. Ultimately, these studies will allow Rwanda to advance in the Progressive Control Pathway (PCP) to reduce or eliminate the burden of AAT.     

Trying to predict and explain the presence of African trypanosomes in tsetse flies.

Trypanosome infections identified by polymerase chain reaction on field-caught tsetse flies from various locations were analyzed with respect to factors intrinsic and extrinsic to the trypanosome-tsetse association. These factors were then simultaneously analyzed using artificial neural networks (ANNs) and the important factors were identified to predict and explain the presence of trypanosomes in tsetse. Among 4 trypanosome subgroups (Trypanosoma brucei s.l., T. congolense of the 'savannah' and of the 'riverine-forest' types, and T. simiae), the presence of the 2 types of T. congolense was predictable in more than 80% of cases, suggesting that the model incorporated some of the key variables. These 2 types of T. congolense were significantly associated in tsetse. Among all the examined factors, it was the presence of T. congolense savannah type that best explained the presence of T. congolense riverine forest type. One possible biological mechanism would be 'hitchhiking,' as previously suspected for other parasites. The model could be improved by adding other important variables to the trypanosome tsetse associations.     

The effect of starvation on the susceptibility of teneral and non-teneral tsetse flies to trypanosome infection

Transmission of vector-borne diseases depends largely on the ability of the insect vector to become infected with the parasite. In tsetse flies, newly emerged or teneral flies are considered the most likely to develop a mature, infective trypanosome infection. This was confirmed during experimental infections where laboratory-reared Glossina morsitans morsitans Westwood (Diptera: Glossinidae) were infected with Trypanosoma congolense or T. brucei brucei. The ability of mature adult tsetse flies to become infected with trypanosomes was significantly lower than that of newly emerged flies for both parasites. However, the nutritional status of the tsetse at the time of the infective bloodmeal affected its ability to acquire either a T. congolense or T. b. brucei infection. Indeed, an extreme period of starvation (3-4 days for teneral flies, 7 days for adult flies) lowers the developmental barrier for a trypanosome infection, especially at the midgut level of the tsetse fly. Adult G. m. morsitans became at least as susceptible as newly emerged flies to infection with T. congolense. Moreover, the susceptibility of adult flies, starved for 7 days, to an infection with T. b. brucei was also significantly increased, but only at the level of maturation of an established midgut infection to a salivary gland infection. The outcome of these experimental infections clearly suggests that, under natural conditions, nutritional stress in adult tsetse flies could contribute substantially to the epidemiology of tsetse-transmitted trypanosomiasis.     

Procyclic tsetse fly midgut forms and culture forms of African trypanosomes share stage- and species-specific surface antigens identified by monoclonal antibodies

Procyclic culture form (PCF) trypanosomes were established from a bloodstream form population of cloned Trypanosoma brucei rhodesiense and were used to immunize mice for hybridoma production. Indirect immunofluorescence was used to select 10 hybridomas which secreted antibodies that bound to the surface of homologous living PCF. The antibodies reacted with PCF of several clones of T.b. brucei, T.b. gambiense, and T.b. rhodesiense, but not with PCF of T. congolense or T. vivax, or with promastigotes of several species of Leishmania parasites. The antigens were not detectable in ethanol/acetic acid-fixed bloodstream forms or in lysates of bloodstream forms of any of the T. brucei subspecies, and are thus species-specific and stage-specific markers. Selected monoclonal antibodies bound to procyclic trypanosomes taken directly from the midgut of infected tsetse flies, and to immature epimastigote forms in salivary probes, and may therefore be useful in epidemiologic investigations.     

Trypanosoma brucei: a membrane-associated protein in coated endocytotic vesicles

Membrane proteins were isolated from purified Trypanosoma brucei coated endocytotic vesicles by phase separation with Triton X-114. The largest abundant membrane protein was a doublet band with a molecular mass of about 77 kDa. A specific antiserum was prepared against this protein by immunization with antigen bands excised from sodium dodecyl sulfate-polyacrylamide gels. Immunoblot analyses with this antiserum showed that the 77-kDa protein was present in other T. brucei, in T. congolense, and in T. vivax bloodstream-stage parasites but absent from procyclic (tsetse fly midgut)-stage trypanosomes. Antigenically related molecules of 58, 300, and 15.5 kDa were also detected. The 300- and 15.5-kDa molecules were not in purified coated vesicles; they were detected in whole bloodstream- and procyclic-form T. brucei organisms. Immunofluorescent studies localized the antigen to the region between the flagellar pocket and the nucleus of bloodstream-form parasites. Ultrastructurally, the antigen was detected on membranes of endosomes and lysosome-like structures that contained endocytosed markers.     

Population vulnerability and disability in Kenya's tsetse fly habitats

Background

Human African Trypanosomiasis (HAT), also referred to as sleeping sickness, and African Animal Trypanosomaisis (AAT), known as nagana, are highly prevalent parasitic vector-borne diseases in sub-Saharan Africa. Humans acquire trypanosomiasis following the bite of a tsetse fly infected with the protozoa Trypanosoma brucei (T.b.) spp. –i.e., T.b. gambiense in West and Central Africa and T.b. rhodesiense in East and Southern Africa. Over the last decade HAT diagnostic capacity to estimate HAT prevalence has improved in active case-finding areas but enhanced passive surveillance programs are still lacking in much of rural sub-Saharan Africa.

Methodology/Principal Findings

This retrospective-cross-sectional study examined the use of national census data (1999) to estimate population vulnerability and disability in Kenya''s 7 tsetse belts to assess the potential of HAT-acquired infection in those areas. A multilevel study design estimated the likelihood of disability in individuals, nested within households, nested within tsetse fly habitats of varying levels of poverty. Residents and recent migrants of working age were studied. Tsetse fly''s impact on disability was conceptualised via two exposure pathways: directly from the bite of a pathogenic tsetse fly resulting in HAT infection or indirectly, as the potential for AAT takes land out of agricultural production and diseased livestock leads to livestock morbidity and mortality, contributing to nutritional deficiencies and poverty. Tsetse belts that were significantly associated with increased disability prevalence were identified and the direct and indirect exposure pathways were evaluated.

Conclusions/Significance

Incorporating reports on disability from the national census is a promising surveillance tool that may enhance future HAT surveillance programs in sub-Saharan Africa. The combined burdens of HAT and AAT and the opportunity costs of agricultural production in AAT areas are likely contributors to disability within tsetse-infested areas. Future research will assess changes in the spatial relationships between high tsetse infestation and human disability following the release of the Kenya 2009 census at the local level.     

Identification of trypanosomes in wild animals from southern Cameroon using the polymerase chain reaction (PCR)

One possible explanation of the maintenance of many historical foci of sleeping sickness in Central Africa could be the existence of a wild animal reservoir. In this study, PCR was used to detect the different trypanosome species present in wild animal captured by hunters in the southern forest belt of Cameroon (Bipindi). Trypanosomes were also detected by a parasitological method (Quantitative buffy coat: QBC). Parasite could not be isolated in culture medium (Kit for in vitro isolation: KIVI). Specific primers of T. brucei s.l., T. congolense forest type, T. congolense savannah type, T. vivax, T. simiae and T. b. gambiense group 1 were used to identify parasites in the blood of 164 animals belonging to 24 different species including ungulates, rodents, pangolins, carnivores, reptiles and primates. Of the 24 studied species, eight were carrying T. b. gambiense group 1. Those parasites pathogenic to man were found in monkeys (Cercocebus torquatus and Cercopithecus nictitans), in ungulates (Cephalophus dorsalis and C. monticola), in carnivores (Nandinia binotata and Genetta servalina) and in rodents (Cricetomys gambianus and Atherurus africanus). 13 species (54%) were carrying T. brucei s.l. identified as non-gambiense group 1.