ABSTRACT
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.
ABSTRACT
La cría de búfalos de agua (Bubalus bubalis) se ha convertido en una ganadería cada vez más importante y común en nuestro país; sin embargo, afecciones como las gastroenteritis parasitarias representan una de las limitantes en el desarrollo de esta especie, provocando un impacto negativo sobre la producción cárnica y lechera. Los principales agentes etiológicos responsables de esta afección son los estróngilos digestivos (Nematoda: Strongylida) y coccidias del género Eimeria (Sporozoa: Eucoccidida). Con el objetivo de determinar el comportamiento de estas infecciones, se evaluaron mediante exámenes coprológicos mensuales a través de la técnica cuantitativa de McMaster, búfalos de cuatro grupos etarios (bumautes entre 8 y 18 meses de edad, bumautes mayores de 18 meses, sementales y búfalas), de ambos sexos, pertenecientes a un rebaño comercial del estado Falcón. Los estróngilos digestivos y las coccidias fueron los más prevalentes, con 25,2 y 46,2%, respectivamente. La abundancia del rebaño fue de 38±41,1 huevos por gramo (HPG) de heces para estróngilos y de 142,4±117,2 ooquistes por gramo (OPG) de heces para coccidias. Hubo diferencias estadísticas (p<0,05) al comparar los valores de prevalencia y abundancia de las infecciones por estróngilos digestivos y coccidias entre los grupos etarios y el sexo. Los valores de prevalencia y abundancia disminuyeron con la edad de los animales evaluados (estróngilos: prevalencias de 39,5; 34,0; 42,3; 15,8% y abundancias de 79,8; 47,2; 30,8; 12,2 HPG; coccidias: prevalencias de 71,3; 54,8; 38,5; 34,0% y abundancias de 379,1; 121,0; 44,2; 47,6 OPG), siendo superiores en machos que en hembras (estróngilos: prevalencias de 36,2 y 22,4%, y abundancias de 70,5 y 30,9 HPG; coccidias: prevalencias de 57,3 y 43,6% y abundancias de 166,3 y 131,5 OPG, respectivamente). Las mayores cargas parasitarias y las infecciones de importancia clínica se observaron en los bumautes entre 8 y 18 meses de edad (contajes mayores a 500 HPG y 5050 OPG). Las condiciones climáticas se encontraron en rangos favorables (25,6-29,3ºC, 77,0-89,0% de humedad relativa y 1,0-151,3 mm de precipitación) para el desarrollo de las formas preparasíticas de estróngilos digestivos y coccidias.
The breeding of water buffaloes (Bubalus bubalis) has become an increasingly important and common livestock in Venezuela; however, conditions such as gastrointestinal parasitism are one of the major constraints in the development of this species, with a negative impact on meat and milk production. The main etiologic agents responsible for this condition are digestive strongyles (Nematoda: Strongylida) and coccidia of the genus Eimeria (Sporozoa: Eucoccidida). This investigation evaluated the behavior of these infections in buffaloes of different age and sex. Samples were collected and examined monthly by the quantitative McMaster technique. The buffaloes were subdivided into four age groups (animals between 8 and 18 months of age, over 18 months, males and female buffaloes), the animals came from a commercial flock of the State of Falcon, Venezuela. The results show that the most prevalent parasites were strongyles and coccidian, 25.2% and 46.2%, respectively. The flock abundance was 38±41.1 eggs per gram (EPG) for strongyles and 142.4±117.2 oocysts per gram (OPG) forcoccidia. There were statistical differences (p <0.05) between age groups and sex of the buffalo, when comparing the values of prevalence and abundance of infections for gastrointestinal strongyles and coccidia. The prevalence and abundance values decreased, with increasing age of the animals tested (strongyles: prevalence of 39.5; 34.0; 42.3; 15.8% and abundance of 79.8; 47.2; 30.8; 12.2 EPG; coccidian: prevalence of 71.3; 54.8; 38.5; 34.0% and abundance of 379.1; 121.0; 44.2; 47.6 OPG), being higher in males than in females (strongyles: prevalence of 36.2 and 22.4%, and abundance of 70.5 and 30.9 EPG; coccidian: prevalence of 57.3 and 43.6% and abundance of 166.3 and 131.5 OPG). The highest parasitic loads and the clinically important infections were seen in 8 to 18 months old buffaloes (counts higher than 500 EPG and 5,050 OPG). Environmental conditions fell within favorable ranges (25.6-29.3ºC of temperature, 77.0-89.0% of relative humidity and 1.0-151.3 mm of precipitation) for the development of infective parasite forms of both digestive strongyles and coccidian.