Degree of technification of the sheep herd may be associated with seropositivity for the maedi-visna virus In South Brasil

Maedi-Visna (MV) is a chronic progressive multisystem disease that may be asymptomatic for several months or years, but progress rapidly, and may result in death, when signs and symptoms evolve. Viral elimination occurs mainly through direct contact with positive animal secretions. There is no vaccine or treatment, and prophylaxis is necessary for the health of the herd. The present study aimed to verify the seropositivity of MV and evaluate the factors associated with the risk in sheep herds in Paraná. A total of 1549 serum samples were collected from 90 properties. An epidemiological questionnaire was applied to each property, and the variables were analyzed using the Epi-info program and R environment. Of the 1549 samples analyzed, 22 were positive (1.4%) for the micro-AGID test in 13.3% of the properties. Our study demonstrated variables associated with the prevention and the risk of seropositivity to MVV. Conducting a breeding season, supplying concentrated feed, and separating the breeding stock before birth were factors associated with protection, whereas the previous occurrence of problems with lice, breeding on pasture, and keeping cats close to the flock were factors associated with risk. The seropositivity observed in the present study suggests the circulation of MVV in sheep herds in Paraná, which reinforces the need to implement prevention and control measures since the level of technification may be associated with the occurrence of anti-MVV antibodies in herds.