Seroepidemiological study of maedi-visna in sheep in Ceara, Rio Grande do Norte, Paraíba, and Sergipe States

Abstract

The production performance of a livestock herd can be compromised by various diseases. In sheep, maedi-visna (MV) infections, which have a chronic nature, are caused by a virus (maedi-visna virus (MVV)) belonging to the genus Lentivirus of the Retroviridae family. The infection can cause significant economic losses and has considerable health impacts on sheep breeding in production systems. Due to the importance of this disease in sheep flocks, the objective was to conduct a serosurvey of MVV in the states of Ceará (CE), Rio Grande do Norte (RN), Paraíba (PB), and Sergipe (SE). A total of, 3332 serum samples were collected in the four states, 1011 in CE, 931 in RN, 459 in PB, and 931 in SE, with the number of samples proportional to the actual herd size of each state. The samples were analyzed using the agar gel microimmunodiffusion test (AGID). Reproducers were revaluated using western blotting (WB). In addition to this serological survey, we administered an investigative questionnaire to identify possible risk factors that facilitate the introduction and spread of diseases (location, category, sex, breed type, creation system, production, herd size, and association with goats). After analysis of the sera using the AGID test, there was zero prevalence. Revaluating breeders by WB revealed a 5.5% prevalence of MV in the four states studied, with prevalences for the states of CE, RN, Paraiba, and SE of 2.3% (2/88), 10.4% (8/77), 3.6% (1/28), and 4.7% (2/42), respectively, corresponding to 13 breeders containing antibodies to the virus. These findings emphasized that the choice of diagnostic tests is extremely important for the early detection of seropositive animals and thus the prevention of the spread of the virus among herds in the region.