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.

Estudio In Vivo de la Carga Parasitaria y Especies de Nematodes Gastrointestinales de la Familia Strongylidae en Caballos Criollos Venezolanos / In Vivo Study of Parasitic Burden and Species of Strongylidae Gastrointestinal Nematodes in Venezuelan Creole Horses

Durante un ensayo para evaluar la eficacia de dos formulaciones antihelmínticas para bovinos (Moxidectina como Cydectin NF® y Doramectina como Dectomax®), se estudiaron in vivo la carga parasitaria y las especies de estrongilidos presentes en caballos criollos venezolanos con altos contajes de estróngilos. El estudio fue llevado a cabo en la Estación Experimental “La Iguana” de la Universidad Simón Rodríguez (UNESR), Municipio Santa María de Ipire, estado Guárico (Venezuela), en cuatro caballos adultos con alto contaje de estróngilos (más de 1000 huevos por gramo de heces, hpg) mediante recuperación de parásitos post-tratamiento. Los animales fueron asignados a uno de los siguientes grupos (una hembra y un macho en cada uno); G1M: tratados con 0,4 mg/kg de peso corporal (PC) de Moxidectina, vía subcutánea (sc); G2D: tratados con 0,3 mg/kg de PC de Doramectina vía sc. Se tomaron muestras fecales (500 g aproximadamente) a las 24 y 48 h post-tratamiento para la recuperación in vivo de las especies de nemátodos Strongylidae presentes. En los animales tratados con Moxidectina sólo se obtuvieron nemátodos a las 48 h post-tratamiento. En los animales machos se recuperaron 325 parásitos, mientras que en las hembras se recuperaron 201 parásitos de la familia Strongylidae. En el grupo tratado con Doramectina, se observaron nemátodos a las 24 y 48 h post-tratamiento. En los machos se recuperaron 136 parásitos y en la hembra sólo tres parásitos. Se observaron seis géneros: Cylicocyclus, Coronocyclus, Cyathostomum, Cylicostephanus, Triodontophorus y Poteriostomum, y 16 especies, siendo Cylicocyclus nassatus la especie con mayor abundancia e intensidad. Posteriostomum imparidentatum se reporta por primera vez en caballos criollos venezolanos. La recuperación de parásitos post-tratamiento es una buena alternativa para la estimación de la carga y composición de la comunidad de parásitos estrongilidos cuando las necropsias no son posibles o no son deseables.

During an assay to evaluate the efficacy of two bovine anthelminthic formulations (Moxidectin as Cydectin NF® and Doramectin as Dectomax®), the in vivo parasitic burden and the strongyles species present in four adult Venezuelan Creole horses with a high strongylid count were studied. The study was carried out at Estación Experimental “La Iguana” de la Universidad Simón Rodríguez (UNESR), Municipio Santa María de Ipire, estado Guárico (Venezuela). A total of four adult horses with a high strongylid count (more than 1000 eggs per gram of feces) through a post treatment parasite recovery were used. Horses were allocated into 2 groups (one male and one female per group), as follows: Group I: two animals treated with a subcutaneous (sc) injection of 0.4 mg/kg body weight (BW) of Moxidectin; Group II: two animals treated with a sc injection of 0.3 mg/kg BW of Doramectin. Samples of feces (approximately 500 g) were collected at 24 and 48 h post-treatment for the in vivo recovery of the strongyles species present. The results showed that nematodes were only seen in animals from Group I 48 h post-treatment: 325 individual parasites of the Strongylidae family were recovered in males and only 201 in females. In Group II, nematodes were observed at 24 and 48 h post treatment, with 136 parasites recovered in males and only 3 in females. Six genuses were observed: Cylicocyclus, Coronocyclus, Cyathostomum, Cylicostephanus, Triodontophorus y Poteriostomum and sixteen species, being Cylicocyclus nassatus the species with more abundance and intensity. Posteriostomum imparidentatum is reported for the first time in Venezuelan Creole horses. The post-treatment parasite recovery is a good alternative for the estimation of the parasite burden and the composition of the strongylid parasite community when necropsy studies are not available or desirable.

Prevalencia de trypanosoma spp. mediante ELISA e inmunofluorescencia indirecta en tres rebaños de búfalos de agua del estado Cojedes, Venezuela / Prevalence of trypanosoma spp. by ELISA and indirect fluorescent antibody test in three water buffaloes herds from the State of Cojedes, Venezuela

Animal trypanosomiasis is a disease caused by parasites of the genus Trypanosome. This malady is widely distributed in many countries, located in tropical and subtropical areas of the world where blood-sucking flies are present. Water buffaloes are important domestic animals used for meat and milk production, and draught power. Buffalo herds are raised in areas where trypanosomiasis is endemic. In Venezuela, the buffalo industry is becoming a very important and common livestock. However, animals imported from non-endemic areas may suffer severe infections. The development of methods which ensure an efficient epidemiological surveillance against this disease is of great relevance. The immunological tests are of great importance for this purpose, because of the low sensitivity of the current parasitological methods, due to the low parasite burden that occur in subclinical and chronic infections caused by trypanosomes. To estimate the serological prevalence of trypanosome in water buffaloes, an enzyme-linked immunosorbent assay (ELISA) was used in buffalo samples of healthy animals from the municipalities of Rómulo Gallegos, Ricaurte and Girardot, in the State of Cojedes, Venezuela. Additionally, samples were also assessed with the indirect fluorescence antibody test (IFAT) and the microhematocrit test (MHCT). A total of 180 blood samples, none of which had an active parasitemia by TMC, were assessed. The prevalence determined by ELISA was 45.56%, which was significantly (P<0.05) higher than that obtained by IFAT (28.89%). The results of the experiments showed a moderate Kappa index of concordance of 0.45 (95% CI: 0.31-0.58); whereas the concordance value for both tests was 73.33%. Both the sensitivity and specificity of ELISA, compared to the IFAT, was 82.69% and 69.53%, respectively. The predictive positive and negative values were 52.44% and 90.82%, respectively. The findings suggest an endemic condition, with moderate infection values caused by Trypanosoma spp. in buffaloes from these regions of Venezuela and show, for the first time, the usefulness of ELISA for epidemiological studies of trypanosomiasis.