Investigation of Neospora caninum seroprevalence and potential impact on reproductive success in semi-free-ranging Père David's deer (Elaphurus davidianus)

This study aimed to determine the prevalence and reproductive impact of Neospora caninum in a herd of semi-free-ranging Père David's deer (Elaphurus davidianus) at a conservation facility, following a suspected abortion storm in 2008. Serum samples (n=103) collected from 60 individuals between 2002 and 2011 were evaluated using competitive ELISA for the detection of N. caninum-specific antibodies. Of the 103 samples, 73 (70.9 per cent) were positive for N. caninum antibodies, with a mean±sd competitive inhibition (CI) of 77.6±19.8 per cent. Thirty (29.1 per cent) samples were seronegative, with mean CI of 15.2±9.70 per cent. A significant negative linear relationship was noted between the proportion of seropositive animals and age (R(2)=0.228, P<0.001). Calving rates of adult females from 2005 to 2011 ranged from 15.4 per cent to 52 per cent (mean 35.5±11.3 per cent), and did not correlate with mean CI values (Spearman's rank correlation coefficient=0.072, P=0.878). While both horizontal and transplacental transmission are likely contributing to persistent herd seropositivity, the role of N. caninum in reproductive success in this and other populations of endangered ungulates remains to be explored.