Field and experimental symptomless infections support wandering donkeys as healthy carriers of Trypanosoma vivax in the Brazilian Semiarid, a region of outbreaks of high mortality in cattle and sheep. Issue 1 (December 2015)

• Record Type: Journal Article
• Authors: Rodrigues, Carla; Batista, Jael; Lima, Joseney; Freitas, Francisco; Barros, Isabella; Garcia, Herakles; Rodrigues, Adriana; Camargo, Erney; Teixeira, Marta
• Is Part Of: Parasites & vectors. Volume 8:Issue 1(2015)
• Page Start: 1
• Page End: 11
• Publication Date: 2015-12
• Subjects: Trypanosoma vivax -- Donkey -- Reservoir -- PCR-diagnosis -- Trypanotolerance -- Molecular epidemiology -- Genotyping -- South America; Parasitism -- Periodicals; Parasites -- Periodicals; Vector-pathogen relationships -- Periodicals; Animals as carriers of disease -- Periodicals; Insects as carriers of disease -- Periodicals; 616.96
• DOI: 10.1186/s13071-015-1169-7
• Languages: English
• ISSNs: 1756-3305

Abstract

Abstract Background The Brazilian Semiarid is the home of the largest herd of donkeys in South America and of outbreaks ofTrypanosoma vivax infection of high mortality in dairy cattle and sheep. For a comprehensive understanding of the underlying mechanisms of these outbreaks and epidemiological role of donkeys, we surveyed forT. vivax in wandering donkeys and follow the experimental infection of donkeys and sheep with a highly virulent isolate from the Semiarid. Methods Blood samples from 180 randomly selected wandering donkeys from the Brazilian Semiarid region were employed for PCV and parasitemia assessments and tested using theT. vivax -specific TviCATL-PCR assay. PCR-amplifed Cathepsin L (CATL) sequences were employed for genotyping and phylogenetic analysis. Four wandering donkeys were experimentally infected with aT. vivax isolate obtained during an outbreak of high mortality in the Semiarid; the control group consisted of two non-inoculated donkeys. Results We detectedT. vivax in 30 of 180 wandering donkeys (16.6 %) using TviCATL- PCR. The prevalence was higher during the dry (15.5 %) than the wet season (1.1 %) and more females (23.1 %) than males (8.9 %) were infected. All the PCR-positive donkeys lacked patent parasitemia and showed normal values of body condition score (BCS) and packed cell volume (PCV). To evaluate the probable tolerance of donkeys toT. vivax, we inoculated five donkeys with a highly virulent isolate (TviBrRp) from the Semiarid. All inoculated donkeys became PCR-positive, but their parasitemia was always subpatent. A control goat inoculated with TviBrRp showed increasing parasitemia concurrently with fever, declining PCV, tachycardia, mucous membrane pallor, enlarged lymph nodes and anorexia. None of these signs were observed in donkeys. However, T. vivax from wandering donkeys shared identical or highly similar genotypes (identified by Cathepsin L sequences) with isolates from cattle and sheep outbreaks of acute disease in the Semiarid. Conclusions This is the first report ofT. vivax in donkeys in Brazil and, to our knowledge, the first experimental infection of donkeys withT. vivax . The symptomless field and experimental infections corroborated that donkeys are more tolerant toT. vivax than other livestock species as shown in African countries. Therefore, farmers, veterinaries and control programmes should be aware of healthy carrier donkeys as a possible source ofT. vivax for susceptible livestock species in the Brazilian Semiarid.