Study on outbreak of Neospora caninum-associated abortion in dairy cows in Calabria (Southern Italy)

Introduction - Neospora caninum is an apicomplexan protozoon causing abortion in cattle worldwide. Infected cows represent economic losses due to fetal abortion, stillbirth, clinical and subclinical disease, impaired milk production, neonatal deaths, reduced fertility and reduced value of infected cows. The abortion caused by neosporosis occurs at 5-6 months gestation. Serological techniques are primarily employed to detect specific antibodies against N. caninum to differentiate infected from non-infected animals and to assess the situation into a herd with regard to abortions due to infection with N. caninum. The herd prevalence rates of N. caninum infection reported in several European countries range from 16% in Sweden to 80% in Spain. Aim - The present study was designed to assess the role of N. caninum for causing abortion in dairy farms in the central area of Calabria region (Southern Italy), by applying the ELISA serologic test. Materials and methods - For the study of outbreak of neosporosis, blood samples were collected from 163 aborted dairy cows. Antibodies to N. caninum were assayed by using a home-made ELISA kit (Istituto Zooprofilattico Sperimentale del Mezzogiorno, Italy). Prevalence of N. caninum-positive herds were determined using WinEpiscope software version 2.0. Results and discussion - IgG against N. caninum were found in nearly 34%(55/163) cases. The dams of the three calves with poor vital signs and neurological disorders were serologically seropositive in ELISA test. The frequency of infection by N. caninum recorded in the sample demonstrates a discrete circulation of the parasite in the territory concerned. Although the presence of antibodies to N. caninum - in cattle only indicate expose to the parasite, probability of abortion in seropositive cattle is twice higher than in seronegative cattle. So, is plausible to correlate the abortion with the frequency of infection recorded. In all dairy herds examined, dogs can be found roaming around farms and have the close contact with cattle. These dogs might be the source of infection, contributing to the high prevalence of N. caninum antibodies in cattle by contaminating the farm with oocysts. Conclusion - Results of the present survey agree with that reported from similar studies about the serological prevalence of neosporosis and it seems to support the outbreak of N. caninum-associated abortion in dairy cows in Calabria region (Southern Italy).