Serological studies on porcine Pneumocystis carinii pneumonia: kinetics of the antibody titers in swine herds and the association of porcine reproductive and respiratory syndrome virus infection.

Serological titers to Pneumocystis carinii (Pc) and porcine reproductive and respiratory syndrome virus (PRRSV) were measured on a herd with epidemic Pc pneumonia (case herd) and two comparison herds, by an indirect fluorescent-antibody technique. In the case herd, the geometric mean titer (GMT) for Pc were 1:80 in pigs 1 week old, 1:10 in pigs 5 weeks old, and 1:80 to 1:190 in pigs over 6 weeks old. GMTs for PRRSV were > 1:145 in most of age groups over 7 weeks old. In comparison herds, Pc and PRRSV antibody titers were low in weanling pigs. The results clarified the kinetics of antibodies to Pc and concurrent infection of PRRSV in the case herd.