Epidemiological characterization and risk factors associated with lentiviral infection of small ruminants at animal fairs in the semiarid Sertão region of Pernambuco, Brazilian semiarid

Abstract

Animal agglomerations at commercial events such as trade fairs represent an important facilitator in infectious disease transmission. Thus, it is crucial to understand the epidemiology of infectious diseases in small ruminants. The objective of this study was to examine lentiviral presence in goats and sheep traded at the animal fair of Tabira city (Sertão region of Pernambuco) and identify possible risk factors associated with infection. We collected serum samples from 233 crossbred goats and 119 crossbred sheep, belonging to 12 breeders, at the Tabira livestock fair from November 2014 to June 2015. An epidemiological questionnaire was used to analyze the risk factors. Agar gel immunodiffusion (AGID) and western blotting (WB) were performed to diagnose small ruminant lentivirus (SRLV) infection. In the AGID test, we used maedi-visna virus (MVV) antigens for sheep and caprine arthritis/encephalitis virus (strain Cork) (CAEV-Co) antigen for goats. The WB analysis used CAEV-Co antigen for both species. Variables from the questionnaire were analyzed with univariate and multivariate statistics. One seropositive goat but no sheep was identified via AGID. According to the WB results, 15/233 goats (6.44%; CI95% = 3.94 - 10.35%) and 8/119 sheep (6.72%; CI95% = 3.45 - 12.71%) were seropositive, totaling 23/352 reactive animals (6.53%; CI95% = 4.39 - 9.61%) from 12 herds. Annual vermifugation of the animals was a significant risk factor (odds ratio = 5.9; CI95% = 1.7-19.8; p = 0.04) for disease in goats, but no variables associated with infection risks were identified in sheep. We concluded that SRLV was present in goats and sheep at the animal fair. Western blots were more sensitive than AGID for SRLV diagnosis. Practices aiming to improve sanitary management may reduce the risk of infection in goats. All studied herds included animals identified as seropositive for SRLV. Therefore, we recommend adopting measures that increase disease diagnosis while intensifying traffic control and surveillance of animal agglomerations.