Trypanosomiasis in Venezuelan water buffaloes: association of packed-cell volumes with seroprevalence and current trypanosome infection

Abstract

The seroprevalence of trypanosomiasis and the prevalence of current trypanosome infection in water buffaloes from the most important livestock areas of Venezuela were evaluated by IFAT and the microhaematocrit centrifugation technique, respectively. The usefulness of a PCR-based assay for identifying the trypanosome species in the buffaloes was also evaluated. Of the 644 animals investigated, 40 (6.2%) were found infected with trypanosomes by blood centrifugation, and 196 (30.4%) were found positive for anti-trypanosome antibodies, by IFAT. The results of the PCR-based assay indicated that 92.5% of the animals with current infections were infected with Trypanosoma vivax and the rest with T. theileri (the first molecular confirmation of T. theileri in Venezuelan water buffaloes). The national programme to treat and prevent trypanosome infections in the buffaloes does not appear to be meeting with great success, even though it is focused on T. vivax. Although the level of parasitaemia was categorized as low for 28 (70%) of the infections detected (and packed-cell volumes appeared to be unassociated with IFAT result, and uncorrelated, in the infected animals, with level of parasitaemia), the 40 infected buffaloes had a significantly lower mean packed-cell volume than the uninfected animals (P<0.05). Farmers should therefore be made aware of the probability of trypanosome-attributable losses in buffalo productivity.

Microsatellite analysis supports clonal propagation and reduced divergence of Trypanosoma vivax from asymptomatic to fatally infected livestock in South America compared to West Africa

“…Two isolates were from an outbreak in the south-eastern region (São Paulo) from cattle that exhibited severe haematological changes [22]. The Venezuelan isolates were from cattle, buffalo and sheep from the endemic Llanos region (Figure 1), where the infected animals are generally asymptomatic but can sporadically show moderate parasitaemia and anaemia [32,33]. The isolates from West Africa included in this study were all from low parasitemic cattle showing mild anemia and were collected in T. vivax endemic settings in Burkina Faso, The Gambia, Ghana, Benin and Nigeria.…”

“…Outbreaks of acute haematological and neurological disorders with high mortality have been reported affecting cattle, goats, sheep and horses throughout non-endemic Brazilian regions [20-22,29]. In South American (SA) regions of enzootic stability (Amazonian lowlands, Venezuelan Llanos and Brazilian wetland of the Pantanal), infections are mostly asymptomatic in cattle, buffaloes and sheep, all showing low parasitaemias [1,30-33]. …”

Evaluation of animal performance, feed intake, and economic losses in sheep experimentally infected with Trypanosoma vivax

“…These problems are due, among other factors, to the range of vectors, susceptible hosts, and the immunodeficiency of the animals, as well as to malnutrition in these herds (GARCIA et al, 2006). In addition, the presence of other diseases can aggravate the general state of the animals, leading to death.…”

Highly debilitating natural Trypanosoma vivax infections in Brazilian calves: epidemiology, pathology, and probable transplacental transmission

“…vivax was introduced into Latin America with cattle imported from Africa, probably in the late nineteenth century, and nowadays is a widespread parasite in Central and South America (Jones and Dávila 2001;Cortez et al 2006Cortez et al , 2009. The transportation of cattle herds had been the mean of dispersion for T. vivax related to many countries such as French Guyana, Colombia, Panama, Bolivia, Venezuela, and Costa Rica (Silva et al 1998;Desquesnes 2004;García et al 2006;Oliveira et al 2009). In Brazil, T. vivax was initially reported in Pará State, where the parasite was detected in a water buffalo showing fever and emaciation (Shaw and Lainson 1972).…”