The absence of anti-rabies antibody in the sera of feral raccoons (Procyon lotor) captured in Hokkaido, Japan.

Feral raccoons captured in Hokkaido, Japan were examined for the presence of rabies virus neutralizing antibody (VNA). Between 2000 to 2002, 741 serum samples were collected and then subjected to VNA titer determination by rapid fluorescent focus inhibition test (RFFIT). Sera showing RFFIT titers of > or =1:25 have been considered as positive according to previous reports. VNA was detected in none of serum samples from the feral raccoons. The present study provides valuable background information for rabies prevention in Japan. The potential risk of raccoon-derived rabies in the wilderness has been of concern because of the increasing number of feral raccoons originally introduced from rabies-endemic countries. The continuous monitoring of sick and/or dead wild raccoons would help to prevent an epidemic spread of raccoon rabies.