Neospora caninum in dairy herds in Schleswig-Holstein, Germany.

The aim of a cross-sectional survey performed between November 2005 and April 2006 was to obtain actual information on the occurrence of Neospora (N.) caninum infection in dairy cows of Schleswig-Holstein. It was planned to examine tank-milk of about 35% of the approximately 6,000 dairy herds in Schleswig-Holstein for N. caninum-specific antibodies using a p38-tank-milk ELISA. This test is able to detect a within-herd N. caninum-seroprevalence of > 10%. Only 20 (1.0%) out of 1,950 tank-milk samples from Schleswig-Holstein reacted N. caninum-positive. A significantly higher proportion of positive herds came from districts with a human population density > 125 per km2 (P = 0.022, Fisher exact test). These districts were located close to the city of Hamburg. A prior survey in Rhineland-Palatinate performed with the same ELISA had revealed a proportion of 7.9% of tank-milk-positive herds. The results of the present survey therefore confirm prior assumptions that N. caninum infections are variably distributed in different German federal states. Similar to the results obtained in Rhineland-Palatinate, the observation of positive herds in the present study was associated with an elevated population density.