Neospora caninum: seroepidemiology of cows and dogs from milk farms of Cunha, Sao Paulo, Brazil

Neosporosis, a parasitic disease prevalent worldwide, is caused by the protozoan Neospora caninum, an obligatory intracellular parasite that can cause abortions and infertility in females, resulting in high economic losses. The aim of this study was to determine the seroprevalence of antibodies against N. caninum in dairy cattle, and the occurrence of antibodies in dogs from farms in the municipality of Cunha, Sao Paulo, Brazil. Additionally, eighteen months after the primary study, an analysis to determine the incidence, seroconversion, and occurrence of anti-N. caninum antibodies was conducted in cows. Sampling was carried out in two phases: during the first one, 400 dairy cattle and 50 dog blood samples from 40 farms were collected. During the second phase, blood samples were collected from 119 cows belonging to 16 farms visited 18 months before. Serum samples were analyzed by indirect immunofluorescence (IFI) with titers >= 100 for cattle and >= 50 for dogs considered as positives. The occurrence of antibodies against N. caninum was 15.0% (60/400) and 14.0% (7/50) for cattle and dogs, respectively. After 18 months, the observed incidence of antibodies was 7.4% (4/54), the conversion detected was 71.4% (seropositive to seronegative) and 7.4% (seronegative to seropositive animals), and the observed occurrence was 7.56% (9/119). The calculated odds ratio (OR) was significant (p < 0.05) for abortions, presence of dogs, and parturition stalls. However, protection factors were identified in 2- to 4-year-old dairy cattle and in the number of lactating cows <= 10 animals. Thus, the presence of antibodies against N. caninum in the studied suggested both vertical and horizontal transmission are occurring in cattle.