Occurrence of antibodies against Neospora caninum in sows and factors associated with infection in commercial herds in two regions of the state of Santa Catarina, Brazil

Neosporosis is a disease that affects ruminants, horses, swine, and wild animals, causing reproductive disorders and economic losses. The importance of the infection in pigs has not been fully elucidated. The objective of the present study was to verify the occurrence of antibodies against Neospora caninum and the possible factors associated with infection in swine herds from two regions of the state of Santa Catarina, Brazil. A total of 498 blood samples were collected from sows of western (five properties) and southern (four properties) regions of the state, and an epidemiological questionnaire was administered. Sera obtained from the blood were tested by indirect fluorescent antibody test (IFAT) (cutoff point 1:50) using tachyzoites of N caninum NC1 strain as antigen. Positive samples were two-fold serially diluted until maximum reactivity titer. The results were analyzed using Fisher and Chi-square tests to determine correlation between serology and associated factors. The overall prevalence was 18.9% (94/498) with titers of 50 (27), 100 (26), 200 (22), 400 (10), and 800 (9). Eighty of 256 samples (31.3%) from the western region were positive, while 14 out of 242 samples (5.8%) from the southern region were positive. A correlation (p < 0.01) was observed among the seroprevalence and contact with dogs (OR = 3.97, IC 2.64-6.43), presence of rodents (OR = 7.37 IC 4.06-13.50), and water source (OR = 2.38 IC 1.44-3.91). The use of anti-bird nets was identified as a protective factor against infection (OR = 0.36 IC 0.07-0.25). These results demonstrate the high prevalence of antibodies against N. caninum in commercial swine herds in the state of Santa Catarina compared to that in other regions of Brazil.