Trypanosoma Lewisi Research Articles

Biological attributes of the kissing bug Triatoma rubrofasciata from Vietnam

BackgroundTriatoma rubrofasciata is the only kissing bug species distributed globally. In the Americas, this species transmits the parasite Trypanosoma cruzi, responsible for Chagas disease. The presence of T. rubrofasciata in several Asian countries has greatly increased recently. In Vietnam, it is found in large numbers, closely associated with human environments. Although T. rubrofasciata from Asia is not infected with Tryp. cruzi, it carries other parasites such as Trypanosoma lewisi and Trypanosoma conorhini. Reports of bites by T. rubrofasciata have increased significantly in several places of Vietnam, becoming a public health problem as it produces severe anaphylactic reactions.MethodsSpecimens of T. rubrofasciata were collected from seven provinces in central Vietnam. We analyzed different biological attributes (life-cycle, starvation resistance, feeding and reproductive capacities) and genetic characteristics (chromosomes and DNA sequences) of T. rubrofasciata from Vietnam and compared them with Brazilian specimens. Natural infection with Tryp. conorhini and Tryp. lewisi were analyzed in a sample of 100 collected insects.ResultsSpecies identification of T. rubrofasciata from central Vietnam was corroborated by genetic markers. Cytogenetic analyses showed that T. rubrofasciata from central Vietnam share the same chromosomal characteristics with individuals from Brazil and Hanoi. DNA sequence analyses of a mitochondrial cytochrome b gene fragment showed little variation between Old and New World specimens. Our study sample, compared with Brazilian individuals, showed a higher survival capacity revealed by a higher hatching rate (98% compared with 80.5%), a larger amount of blood taken in single meal and long-term starvation resistance. Furthermore, this species had a high natural rate of infection with Tryp. conorhini (46%) and Tryp. lewisi (27%).ConclusionsFor T. rubrofasciata of Vietnam, a high rate of fecundity throughout the year, a high capacity for starvation, and its occurrence in synanthropic environments of urban areas with a high availability of food sources are risk factors to be taken into account by vector control campaigns. The several allergic reactions caused by their bites and their high infection with Tryp. lewisi highlight the need to implement specific control programmes for T. rubrofasciata in Vietnam.

Zoonotic Trypanosomes in Rats and Fleas of Venezuelan Slums.

Rattus spp. are reservoirs of many human zoonoses, but their role in domestic transmission cycles of human trypanosomiasis is underestimated. In this study, we report trypanosome-infected Rattus norvegicus and Rattus rattus in human dwellings in slums neighboring Maracay, a large city near Caracas, the capital of Venezuela. Blood samples of R. norvegicus and R. rattus examined by PCR and FFLB (fluorescent fragment length barcoding) revealed a prevalence of 6.3% / 31.1% for Trypanosoma lewisi (agent of rat- and flea-borne human emergent zoonosis), and 10.5% / 24.6% for Trypanosoma cruzi (agent of Chagas disease). Detection in flea guts of T. lewisi (76%) and, unexpectedly, T. cruzi (21.3%) highlighted the role of fleas as carriers and vectors of these trypanosomes. A high prevalence of rats infected with T. lewisi and T. cruzi and respective flea and triatomine vectors poses a serious risk of human trypanosomiasis in Venezuelan slums. Anthropogenic activities responsible for growing rat and triatomine populations within human dwellings drastically increased human exposure to trypanosomes. This scenario has allowed for the reemergence of Chagas disease as an urban zoonosis in Venezuela and can propitiate the emergence of atypical T. lewisi infection in humans.

Spatio-temporal survey of small mammal-borne Trypanosoma lewisi in Cotonou, Benin, and the potential risk of human infection

Human trypanosomoses are the sleeping sickness in Africa and Chagas disease in Latin America. However, atypical human infections by animal trypanosomes have been described, but poorly investigated. Among them, the supposed rat-specific T. lewisi was shown to be responsible for a few severe cases. In Africa, the scarcity of data and the null awareness about the atypical human trypanosomoses suggest that the number of cases may be higher that currently thought. Furthermore, T. lewisi is resistant to normal human serum and therefore a potential human pathogen. In order to document T. lewisi distribution and ecology, a qPCR- and 16DNA sequencing-based survey was conducted in 369 rodents from three urban districts of Cotonou city, Benin, during three different periods of the same year. Our study demonstrated very high prevalence (57.2%) even when considering only individuals identified as positive through DNA sequencing (39.2%). Black rats represented the most dominant as well as the most T. lewisi-parasitized species. No difference was retrieved neither between seasons nor districts, suggesting a large infestation of rodents by trypanosomes throughout the year and the city. Our results suggest that conditions are gathered for rat to human transmission of T. lewisi in these socio-environmentally degraded urban areas, thus pointing towards the rapidly urbanizing Abidjan-Lagos corridor as a region at particular risk.

Cell cycle and cleavage events during in vitro cultivation of bloodstream forms of Trypanosoma lewisi, a zoonotic pathogen

ABSTRACT Trypanosoma (Herpetosoma) lewisi is a globally distributed rat trypanosome, currently considered as a zoonotic pathogen; however, a detailed understanding of the morphological events occurring during the cell cycle is lacking. This study aimed to investigate the cell cycle morphology and cleavage events of Trypanosoma lewisi (T. lewisi) during in vitro cultivation. By establishing in vitro cultivation of T. lewisi at 37°C, various cell morphologies and stages could be observed. We have provided a quantitative analysis of the morphological events during T. lewisi proliferation. We confirmed a generation time of 12.14 ± 0.79 hours, which is similar to that in vivo (12.21 ± 0.14 hours). We also found that there are two distinct cell cycles, with a two-way transformation connection in the developmental status of this parasite, which was contrasted with the previous model of multiple division patterns seen in T. lewisi. We quantified the timing of cell cycle phases (G1n, 0.56 U; Sn, 0.14 U; G2n, 0.16 U; M, 0.06 U; C, 0.08 U; G1k, 0.65 U; Sk, 0.10 U; G2k, 0.17 U; D, 0.03 U; A, 0.05 U) and their morphological characteristics, particularly with respect to the position of kinetoplast(s) and nucleus/nuclei. Interestingly, we found that both nuclear synthesis initiation and segregation in T. lewisi occurred prior to kinetoplast, different to the order of replication found in Trypanosoma brucei and Trypanosoma cruzi, implicating a distinct cell cycle control mechanism in T. lewisi. We characterized the morphological events during the T. lewisi cell cycle and presented evidence to support the existence of two distinct cell cycles with two-way transformation between them. These results provide insights into the differentiation and evolution of this parasite and its related species.

A preliminary serological study of Trypanosoma evansi and Trypanosoma lewisi in a Chinese human population

Trypanosoma evansi, known as an animal trypanosome, is widely distributed in many countries of Africa, Asia and South America; it causes significant economic loss in these countries. A few cases have also occurred in some countries of Europe due to the importation of infected animals from endemic regions. Rare human T. evansi infections were attended by the health departments and international health organizations in these endemic countries. Trypanosoma lewisi, a cosmopolitan parasite of rats, sometimes found in humans, is currently considered as a zoonotic pathogen and has gained special attention from scientists and international health organizations such as the World Health Organization. The current study considered the serological screening of human infection by T. evansi and T. lewisi in a Chinese human population. None of the 622 samples was found positive for T. evansi infection using the card agglutination test for the trypanosome antigen Rotat 1.2, while, 2.41% of the examined serum samples exhibited some seropositivity to T. lewisi using enzyme-linked immunosorbent assay. No significant difference was found between the samples from areas in the South (Zhaoqing, Guangdong) and Central (Zhengzhou, Henan) China.

Integrative taxonomic approach of trypanosomes in the blood of rodents and soricids in Asian countries, with the description of three new species.

Trypanosoma lewisi (Kinetoplastea: Trypanosomatida: Trypanosomatidae) with a cosmopolitan distribution is the type species of the subgenus Herpetosoma, which includes ca. 50 nominal species isolated mainly from rodents. Since members of Herpetosoma in different host species have an almost identical morphology of bloodstream forms, these trypanosomes are referred to as 'T. lewisi-like', and the molecular genetic characterization of each species is necessary to verify their taxonomy. In the present study, we collected blood samples from 89 murid rodents of 15 species and 11 soricids of four species in Indonesia, Philippines, Vietnam, Taiwan, and mainland China for the detection of hemoprotozoan infection. T. lewisi and T. lewisi-like trypanosomes were found in the blood smears of 10 murid animals, which included Bandicota indica (two rats), Rattus argentiventer (one rat), and Rattus tiomanicus (two rats) in Indonesia; Rattus rattus (one rat) in the Philippines; and Niviventer confucianus (four rats) in mainland China. Furthermore, large- or medium-sized non-T. lewisi-like trypanosomes were detected in two soricids, Crocidura dracula in Vietnam and Anourosorex yamashinai in Taiwan, respectively. Molecular genetic characterization of the small subunit (SSU) ribosomal RNA gene (rDNA) and glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) gene indicated that the trypanosomes from all the murid hosts had identical SSU rDNA or gGAPDH gene nucleotide sequences except for those in N. confucianus in mainland China. These N. confucianus-infecting trypanosomes also showed several unique morphological features such as smaller bodies, anteriorly positioned nuclei, and larger rod-shaped kinetoplasts when compared with T. lewisi trypomastigotes. Trypanosoma (Herpetosoma) niviventerae n. sp. is erected for this new species. Similarly, based on morphological and molecular genetic characterization, Trypanosoma sapaensis n. sp. and Trypanosoma anourosoricis n. sp. are proposed for the trypanosomes in C. dracula in Vietnam and A. yamashinai in Taiwan, respectively. More effort directed toward the morphological and molecular genetic characterization of the trypanosomes of rodents and soricids is required to fully understand the real biodiversity of their hemoflagellates.

Leishmania major and Trypanosoma lewisi infection in invasive and native rodents in Senegal.

Bioinvasion is a major public health issue because it can lead to the introduction of pathogens in new areas and favours the emergence of zoonotic diseases. Rodents are prominent invasive species, and act as reservoirs in many zoonotic infectious diseases. The aim of this study was to determine the link between the distribution and spread of two parasite taxa (Leishmania spp. and Trypanosoma lewisi) and the progressive invasion of Senegal by two commensal rodent species (the house mouse Mus musculus domesticus and the black rat Rattus rattus). M. m. domesticus and R. rattus have invaded the northern part and the central/southern part of the country, respectively. Native and invasive rodents were caught in villages and cities along the invasion gradients of both invaders, from coastal localities towards the interior of the land. Molecular diagnosis of the two trypanosomatid infections was performed using spleen specimens. In the north, neither M. m. domesticus nor the native species were carriers of these parasites. Conversely, in the south, 17.5% of R. rattus were infected by L. major and 27.8% by T. lewisi, while very few commensal native rodents were carriers. Prevalence pattern along invasion gradients, together with the knowledge on the geographical distribution of the parasites, suggested that the presence of the two parasites in R. rattus in Senegal is of different origins. Indeed, the invader R. rattus could have been locally infected by the native parasite L. major. Conversely, it could have introduced the exotic parasite T. lewisi in Senegal, the latter appearing to be poorly transmitted to native rodents. Altogether, these data show that R. rattus is a carrier of both parasites and could be responsible for the emergence of new foci of cutaneous leishmaniasis, or for the transmission of atypical human trypanosomiasis in Senegal.

Predictors of Trypanosoma lewisi in Rattus norvegicus from Durban, South Africa.

This study investigated associations between Trypanosoma lewisi and Xenopsylla cheopis, a common cyclical vector of T. lewisi; Polyplax spinulosa, a reported mechanical vector; and Laelaps echidnina and Laelaps lamborni, 2 rodent mites of Rattus norvegicus in Durban, South Africa. In total, 379 R. norvegicus individuals were live-trapped at 48 sites in 4 locality types around Durban during a 1-yr period. Rats were euthanized, cardiac blood was taken to check for hemoparasites, and ectoparasites were removed for identification. Parasite species richness was higher in pups (2.11) and juveniles (1.02) than adults (0.87). Most rats in the study harbored 1 or 2 of the 5 parasites surveyed. Rats with trypanosomes and fleas were more prevalent in the city center and harbor, where juveniles were most affected. Rats with lice were more prevalent in informal settlements and urban/peri-urban areas, where pups had the highest infestations. There was a significant positive association between rats with fleas and trypanosomes and a negative association between rats with lice and trypanosomes. Location and rat age were significant predictors of T. lewisi, X. cheopis, and P. spinulosa. Mites showed no strong association with trypanosomes. Ectoparasite associations are possibly habitat and life-cycle related. We conclude that Durban's city center, which offers rats harborage, an unsanitary environment, and availability of food, is a high-transmission area for fleas and trypanosomes, and consequently a potential public health risk.

Endoparasites of Small Mammals in Edo State, Nigeria: Public Health Implications

Some small mammals occur as household pests and harbour a number of parasites that could be of public health importance. This study profiled the helminth and protozoan parasites in trapped small mammals within and around human dwelling places (houses) located across 4 major towns (Auchi, Benin, Ekpoma, and Uromi) and environs in Edo state, Nigeria. Six genera (Apodemus sp., Crocidura sp., Mastomys natalensis, Mus musculus, Rattus sp., and Sorex sp.) were identified from 502 trapped small mammals. Overall, M. musculus (71.9%) and Rattus rattus (20.1%) were the most frequently trapped. In total, on examination of blood, gastrointestinal contents, and brain tissues, 12 helminth taxa (Angiostrongylus sp., Aspicularis sp., Capillaria sp., Gongylonema sp., Heterakis spumosa, Hymenolepis diminuta, Hymenolepis nana, Mastophorus muris, Moniliformis moniliformis, Nippostrongylus brasiliensis, Strongyloides sp., Trichosomoides sp., and Trichuris sp.), and 6 protozoan parasites (Babesia sp., Trypanosoma lewisi, Plasmodium sp., Eimeria sp., Isospora sp., and Toxoplasma gondii) were isolated. Most prevalent helminths with relatively heavy mean intensity were Strongyloides sp. and Heterakis spumosa, while Plasmodium, Eimeria, and Isospora were the most prevalent protozoan parasites. Generally, intrinsic factors like sex and age had marginal influence on the rate and burden of infection in M. musculus and R. rattus. Although the infection rate and prevalence of zoonotic parasites were low, they were largely recovered in rodents from Ekpoma. This study elucidates the public health implication of the presence of zoonotic parasites in these small mammals.

Erythrocyte osmotic resistance test as a screening tool for lysosomal diseases

Trypanosoma (Herpetosoma) lewisi is a cosmopolitan parasite of rodents strongly linked to the human dispersal of Rattus spp. from Asia to the rest of the world. This species is highly phylogenetically related to trypanosomes from other rodents (T. lewisi-like), and sporadically infects other mammals. T. lewisi may opportunistically infect humans, and has been considered an emergent rat-borne zoonosis associated to poverty. We developed the THeCATL-PCR based on Cathepsin L (CATL) sequences to specifically detect T. (Herpetosoma) spp., and assess their genetic diversity. This method exhibited high sensitivity using blood samples, and is the first molecular method employed to search for T. lewisi in its flea vectors. THeCATL-PCR surveys using simple DNA preparation from blood preserved in ethanol or filter paper detected T. lewisi in Rattus spp. from human dwellings in South America (Brazil and Venezuela), East Africa (Mozambique), and Southeast Asia (Thailand, Cambodia and Lao PDR). In addition, native rodents captured in anthropogenic and nearby human settlements in natural habitats harbored T. (Herpetosoma) spp. PCR-amplified CATL gene fragments (253 bp) distinguish T. lewisi and T. lewisi-like from other trypanosomes, and allow for assessment of genetic diversity and relationships among T. (Herpetosoma) spp. Our molecular surveys corroborated worldwide high prevalence of T. lewisi, incriminating Mastomys natalensis as an important carrier of this species in Africa, and supported its spillover from invader Rattus spp. to native rodents in Brazil and Mozambique. THeCATL-PCR provided new insights on the accurate diagnosis and genetic repertoire of T. (Herpetosoma) spp. in rodent and non-rodent hosts, revealing a novel species of this subgenus in an African gerbil. Phylogenetic analysis based on CATL sequences from T. (Herpetosoma) spp. and other trypanosomes (amplified using pan-trypanosome primers) uncovered rodents harboring, beyond mammal trypanosomes of different subgenera, some species that clustered in the lizard-snake clade of trypanosomes.

Landscape epidemiology in urban environments: The example of rodent-borne Trypanosoma in Niamey, Niger

Trypanosomes are protozoan parasites found worldwide, infecting humans and animals. In the past decade, the number of reports on atypical human cases due to Trypanosoma lewisi or T. lewisi-like has increased urging to investigate the multiple factors driving the disease dynamics, particularly in cities where rodents and humans co-exist at high densities. In the present survey, we used a species distribution model, Maxent, to assess the spatial pattern of Trypanosoma-positive rodents in the city of Niamey. The explanatory variables were landscape metrics describing urban landscape composition and physiognomy computed from 8 land-cover classes. We computed the metrics around each data location using a set of circular buffers of increasing radii (20m, 40m, 60m, 80m and 100m). For each spatial resolution, we determined the optimal combination of feature class and regularization multipliers by fitting Maxent with the full dataset. Since our dataset was small (114 occurrences) we expected an important uncertainty associated to data partitioning into calibration and evaluation datasets. We thus performed 350 independent model runs with a training dataset representing a random subset of 80% of the occurrences and the optimal Maxent parameters. Each model yielded a map of habitat suitability over Niamey, which was transformed into a binary map implementing a threshold maximizing the sensitivity and the specificity. The resulting binary maps were combined to display the proportion of models that indicated a good environmental suitability for Trypanosoma-positive rodents. Maxent performed better with landscape metrics derived from buffers of 80m. Habitat suitability for Trypanosoma-positive rodents exhibited large patches linked to urban features such as patch richness and the proportion of landscape covered by concrete or tarred areas. Such inferences could be helpful in assessing areas at risk, setting of monitoring programs, public and medical staff awareness or even vaccination campaigns.

Diagnosis and genetic analysis of the worldwide distributed Rattus-borne Trypanosoma (Herpetosoma) lewisi and its allied species in blood and fleas of rodents

Trypanosoma (Herpetosoma) lewisi is a cosmopolitan parasite of rodents strongly linked to the human dispersal of Rattus spp. from Asia to the rest of the world. This species is highly phylogenetically related to trypanosomes from other rodents (T. lewisi-like), and sporadically infects other mammals. T. lewisi may opportunistically infect humans, and has been considered an emergent rat-borne zoonosis associated to poverty. We developed the THeCATL-PCR based on Cathepsin L (CATL) sequences to specifically detect T. (Herpetosoma) spp., and assess their genetic diversity. This method exhibited high sensitivity using blood samples, and is the first molecular method employed to search for T. lewisi in its flea vectors. THeCATL-PCR surveys using simple DNA preparation from blood preserved in ethanol or filter paper detected T. lewisi in Rattus spp. from human dwellings in South America (Brazil and Venezuela), East Africa (Mozambique), and Southeast Asia (Thailand, Cambodia and Lao PDR). In addition, native rodents captured in anthropogenic and nearby human settlements in natural habitats harbored T. (Herpetosoma) spp. PCR-amplified CATL gene fragments (253bp) distinguish T. lewisi and T. lewisi-like from other trypanosomes, and allow for assessment of genetic diversity and relationships among T. (Herpetosoma) spp. Our molecular surveys corroborated worldwide high prevalence of T. lewisi, incriminating Mastomys natalensis as an important carrier of this species in Africa, and supported its spillover from invader Rattus spp. to native rodents in Brazil and Mozambique. THeCATL-PCR provided new insights on the accurate diagnosis and genetic repertoire of T. (Herpetosoma) spp. in rodent and non-rodent hosts, revealing a novel species of this subgenus in an African gerbil. Phylogenetic analysis based on CATL sequences from T. (Herpetosoma) spp. and other trypanosomes (amplified using pan-trypanosome primers) uncovered rodents harboring, beyond mammal trypanosomes of different subgenera, some species that clustered in the lizard-snake clade of trypanosomes.

Endo-parasites of public-health importance recovered from rodents in the Durban metropolitan area, South Africa

Background: Parasite infections of public health importance carried by Rattus spp. on the African continent (excluding toxoplasmosis) have not been adequately researched. The aim of this study was to investigate endoparasites of public health importance, particularly those associated with R. norvegicus, at different locations and seasons within the port-city, Durban.Methods: Four hundred rodents (379 R. norvegicus, 10 R. rattus and 11 Mastomys natalensis) were live-trapped at 60 sites in four locations, during wet and dry seasons in 2009. Rats were humanely euthanased, cardiac blood drawn (for blood smears and serology), ectoparasites removed and dissected. Each organ was separately processed to collect parasites. Binary logistic regression and four-way ANOVAs were used to test for the effects of location, season, rodent age and gender on parasite prevalence, richness and abundance.Results: Eight parasites of public health importance were detected: Gongylonema sp. (25.3%), Trypanosoma lewisi (22.8%), Hymenolepis diminuta (17.2%), Angiostrongylus cantonensis (15.3%), Toxoplasma gondii (11.2%), Moniliformis moniliformis (9.5%), Calodium hepaticum (2.6%) and H. nana (0.8%). Ascaris spp. (probably A. lumbricoides) ova, assumed to have been acquired from consuming infected human faeces were found in rat faeces (4.8%). Parasite species richness was positively associated with location, season and rodent age. Location, season, rat age and gender differentially affected prevalence and worm abundance of parasite species.Conclusions: These occurrence data of parasites of public health importance provide valuable information to local and provincial organisations and medical practitioners for diagnoses of possible zoonoses, and a reference point for further studies in metropolitan areas of Africa.

Observaciones parasitológicas en ratas de San José, Costa Rica

A parasitologic study is presented of 103 adult house rats from various sites in San Jose, Costa Rica. Seven specimens were Rattus rattus rattus, and the rest were Rattus norvegicus. The following protozoa were found in trophic form when feces were examined for eggs and larvae of helminths: Trichomonas, Giardia, Hexamita, Chilomastix, and Entamoeba. Trypanosoma lewisi was found in the blood of 7 out of 17 rats examined (8,8%) The following nematodes and cestodes were found with the incidence indicated: Strongyloides ratti (41,7 %); Aspiculuris tetraptera (1,9 %); Nipostron­gylus brasiliensis (47,6%); Gongylonema neoplasticum (0,9 %); Protospirura muris (8,7%); Trichosomoides crassicauda (23,3%); Taenia taeniformis larvae (33%); Hymenolepis diminuta (43,6%); and H. nana (0,9 %). No larvae of Trichinella spiralis were found in diaphragms examined. The acanthocephalian Moniliformis moniliformis was found in 18,4 per cent of the rats. Arthropods found as ectoparasites were, in arder of incidence, Echino­laelaps echidninus (14,5%), Xenopsilla cheopis (7,7 %) and Ctenopsyllus se­gnis (1,9%). These percent data should be regarded as minimum figures, as only 61 rats were brought alive to the laboratory.

PCR-based identification of Trypanosoma lewisi and Trypanosoma musculi using maxicircle kinetoplast DNA

Trypanosoma lewisi, transmitted by rat fleas, is a widespread pathogen specific to rats with records of human infection cases. Its closely related species with global distribution, Trypanosoma musculi, is transmitted between mice by ingestion of infected fleas. These trypanosomes are of similar morphology, making it difficult to distinguish them by microscopy. In this study, we have developed a rapid, sensitive and reliable PCR method for the diagnosis of T. lewisi and T. musculi. The T. lewisi-specific amplicons were not produced by other Trypanosoma, such as T. musculi, T. brucei complex or T. cruzi, neither by an outgroup of Leishmania amazonensis. The detection limits of the three pairs of T. lewisi-specific primers were 50ng, 1ng and 10ng of total DNA, respectively. The primers designed for T. musculi primers showed specifically that amplicon strictly in T. musculi and their detection limits were 10ng and 1ng of total DNA. To simplify the detection process, we managed to apply our method directly on tail blood samples without complicated DNA purification. In conclusion, PCR with our primers could be a highly sensitive, specific protocol to detect and distinguish T. lewisi and T. musculi from other trypanosomes.

Endo-parasites of public-health importance recovered from rodents in the Durban metropolitan area, South Africa

Background: Parasite infections of public health importance carried by Rattus spp. on the African continent (excluding toxoplasmosis) have not been adequately researched. The aim of this study was to investigate endoparasites of public health importance, particularly those associated with R. norvegicus, at different locations and seasons within the port-city, Durban.Methods: Four hundred rodents (379 R. norvegicus, 10 R. rattus and 11 Mastomys natalensis) were live-trapped at 60 sites in four locations, during wet and dry seasons in 2009. Rats were humanely euthanased, cardiac blood drawn (for blood smears and serology), ectoparasites removed and dissected. Each organ was separately processed to collect parasites. Binary logistic regression and four-way ANOVAs were used to test for the effects of location, season, rodent age and gender on parasite prevalence, richness and abundance.Results: Eight parasites of public health importance were detected: Gongylonema sp. (25.3%), Trypanosoma lewisi (22.8%), Hyme...

Fleas and trypanosomes of peridomestic small mammals in sub-Saharan Mali.

BackgroundFleas are obligate blood-feeding ectoparasites and vectors of several bacterial zoonotic pathogens as well as trypanosomes that parasitize rodents and other small mammals. During investigations of tick- and rodent-borne diseases in Mali, West Africa, we included fleas and rodent-borne trypanosomes, both of which are poorly known in this country, but are attracting greater public health interest.MethodsSmall mammals were captured in 20 Malian villages from December 2007 to October 2011. Fleas were collected and identified to species, and thin blood smears were prepared, stained and examined microscopically for trypanosomes.ResultsWe captured 744 small mammals, 68 (9.1 %) of which yielded fleas. Two species of fleas, Xenopsylla cheopis and Xenopsylla nubica, were collected from six species of rodents and one species of shrew. Multimammate rats, Mastomys natalensis, were hosts for 58.5 % of all fleas collected. Xenopsylla cheopis was found in the moister southern savannah while X. nubica was mostly restricted to the drier Sahel. Trypanosomes were found in 3 % of 724 blood smears, although 91 % of parasitemic animals originated from two villages where black rats (Rattus rattus) and M. natalensis were the primary hosts and X. cheopis the dominant flea. The trypanosomes were morphologically consistent with the Trypanosoma (Herpetosoma) lewisi group, flea-borne hemoflagellates that parasitize domestic rats.Conclusions Xenopsylla cheopis and trypanosomes parasitize peridomestic rats that commingle with people in southern Mali. Given the increasing awareness of flea-borne trypanosomes as possible human pathogens, we hope our findings will stimulate future investigators to examine the potential public health significance of flea-borne trypanosomosis in West Africa.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1818-5) contains supplementary material, which is available to authorized users.

Impact of Anthropogenic Disturbance on Native and Invasive Trypanosomes of Rodents in Forested Uganda.

Habitat disturbance and anthropogenic change are globally associated with extinctions and invasive species introductions. Less understood is the impact of environmental change on the parasites harbored by endangered, extinct, and introduced species. To improve our understanding of the impacts of anthropogenic disturbance on such host-parasite interactions, we investigated an invasive trypanosome (Trypanosoma lewisi). We screened 348 individual small mammals, representing 26 species, from both forested and non-forested habitats in rural Uganda. Using microscopy and PCR, we identified 18% of individuals (order Rodentia) as positive for trypanosomes. Further phylogenetic analyses revealed two trypanosomes circulating-T. lewisi and T. varani. T. lewisi was found in seven species both native and invasive, while T. varani was identified in only three native forest species. The lack of T. varani in non-forested habitats suggests that it is a natural parasite of forest-dwelling rodents. Our findings suggest that anthropogenic disturbance may lead to spillover of an invasive parasite (T. lewisi) from non-native to native species, and lead to local co-extinction of a native parasite (T. varani) and native forest-dwelling hosts.

Zoonotic trypanosomes in South East Asia: Attempts to control Trypanosoma lewisi using human and animal trypanocidal drugs

Beside typical human trypanosomes responsible of sleeping sickness in Africa and Chagas disease in Latin America, there is a growing number of reported atypical human infections due to Trypanosoma evansi, a livestock parasite, or Trypanosoma lewisi, a rat parasite, especially in Asia. Drugs available for the treatment of T. brucei ssp. in humans are obviously of choice for the control of T. evansi because it is derived from T. brucei. However, concerning T. lewisi, there is an urgent need to determine the efficacy of trypanocidal drugs for the treatment in humans. In a recent study, pentamidine and fexinidazole were shown to have the best efficacy against one stock of T. lewisi in rats.In the present study suramin, pentamidine, eflornitine, nifurtimox, benznidazole and fexinidazole, were evaluated at low and high doses, in single day administration to normal rats experimentally infected with a stock of T. lewisi recently isolated in Thailand. Because none of these treatments was efficient, a trial was made with the most promising trypanocide identified in a previous study, fexinidazole 100mg/kg, in 5 daily administrations. Results observed were unclear. To confirm the efficacy of fexinidazole, a mixed infection protocol was set up in cyclophosphamide immunosuppressed rats. Animals were infected successively by T. lewisi and T. evansi, and received 10 daily PO administrations of 200mg/kg fexinidazole. Drastic effects were observed against T. evansi which was cleared from the rat's blood within 24 to 48h; however, the treatment did not affect T. lewisi which remained in high number in the blood until the end of the experiment. This mixed infection/treatment protocol clearly demonstrated the efficacy of fexinidazole against T. evansi and its inefficacy against T. lewisi. Since animal trypanocides were also recently shown to be inefficient, other protocols as well as other T. lewisi stocks should be investigated in further studies.

Phylogenetic analysis of the Trypanosoma genus based on the heat-shock protein 70 gene

Trypanosome evolution was so far essentially studied on the basis of phylogenetic analyses of small subunit ribosomal RNA (SSU-rRNA) and glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) genes. We used for the first time the 70kDa heat-shock protein gene (hsp70) to investigate the phylogenetic relationships among 11 Trypanosoma species on the basis of 1380 nucleotides from 76 sequences corresponding to 65 strains. We also constructed a phylogeny based on combined datasets of SSU-rDNA, gGAPDH and hsp70 sequences. The obtained clusters can be correlated with the sections and subgenus classifications of mammal-infecting trypanosomes except for Trypanosoma theileri and Trypanosoma rangeli. Our analysis supports the classification of Trypanosoma species into clades rather than in sections and subgenera, some of which being polyphyletic. Nine clades were recognized: Trypanosoma carassi, Trypanosoma congolense, Trypanosoma cruzi, Trypanosoma grayi, Trypanosoma lewisi, T. rangeli, T. theileri, Trypanosoma vivax and Trypanozoon. These results are consistent with existing knowledge of the genus' phylogeny. Within the T. cruzi clade, three groups of T. cruzi discrete typing units could be clearly distinguished, corresponding to TcI, TcIII, and TcII+V+VI, while support for TcIV was lacking. Phylogenetic analyses based on hsp70 demonstrated that this molecular marker can be applied for discriminating most of the Trypanosoma species and clades.