Serological prevalence of tularemia in cottontail rabbits of southern Illinois.

Sera of cottontail rabbits (Sylvilagus floridanus) collected in southern Illinois in 1983 and 1984 were screened for the presence of antibodies against Francisella tularensis by rapid slide agglutination and enzyme linked immunosorbent assay techniques; 6% of 118 and 16% of 119 samples were positive by these methods, respectively. Rabbits gained, lost and maintained titers over at least an 8 mo period. Francisella tularensis tularensis was isolated from one serologically negative, clinically healthy rabbit.