Circulation of porcine reproductive and respiratory syndrome virus in swine herds in the Czech Republic

Porcine reproductive and respiratory syndrome (PRRS) was identified as the cause of health disorders in sows and losses in newborn piglets in three herds in 1998. In the herd B, the infection resulted in a marked decrease of pregnancy rate, and in the herds H and D in increased numbers of stillbirths and early deaths of piglets. Demonstration of antibodies to PRRS virus in nine sows of the herd B was followed by demonstration by reverse transcription and polymerase chain reaction of viral RNA in their blood sera as well as in blood sera of two of the twelve tested boars. PRRS virus was isolated in PLM culture from one of the two boars. Tn the herd H, antibodies to PRRS virus were demonstrated in blood serum of 15 of the 16 tested sows. Viral RNA was demonstrated in blood serum of two sows and in lung tissue of two dying piglets and two piglets killed soon after birth. PRRS virus was isolated in PLM culture from the lung suspension of one piglet. In the herd D, viral RNA was demonstrated in blood serum of four sows and three piglets aged 2 to 5 days. PRRS virus was isolated in PLM cultures from blood serum of one of the sows and lung tissue samples of two piglets. The results are an evidence that, following the first detection of PRRS in the Czech Republic in 1995, the causative virus circulated in swine herds and induced clinical disease in some swine herds in 1998.