Atypical Porcine Pestivirus: A Possible Cause of Congenital Tremor Type A-II in Newborn Piglets.

Congenital tremor type A-II in piglets has been regarded as a transmissible disease since the 1970s, possibly caused by a very recently-described virus: atypical porcine pestivirus (APPV). Here, we describe several strains of APPV in piglets with clinical signs of congenital tremor (10 of 10 farms tested). Piglets on a farm with no history of congenital tremor were PCR-negative for the virus.

Pleuritis in slaughter pigs: relations between lung lesions and bacteriology in 10 herds with high pleuritis.

Pleuritis in slaughter pigs has increased in recent years in the Netherlands. The aim of the present study was to determine what respiratory pathogens were involved in pleuritis. In total, lungs of 968 slaughter pigs from 10 herds with high prevalence of pleuritis were morphologically examined for size, location, and type of lesions.

Susceptibility to Actinobacillus pleuropneumoniae infection in pigs from an endemically infected herd is related to the presence of toxin-neutralizing antibodies.

Our objective was to identify pigs of an endemically infected herd that were susceptible to pleuropneumonia due to Actinobacillus pleuropneumoniae. The presence of toxin-neutralizing antibodies was studied in serum of 36 pigs from birth until 24 weeks of age. Titers gradually declined during the first twelve weeks of life and increased thereafter.

Prevalence and development of antibodies neutralizing the haemolysin and cytotoxin of Actinobacillus pleuropneumoniae in three infected pig herds.

Sero-epidemiological studies were carried out in pigs aged 1 to 24 weeks in three herds in which Actinobacillus pleuropneumoniae was endemic. The sera were tested in the complement-fixation test and for their ability to neutralize the haemolytic and cytotoxic activities of the A. pleuropneumoniae serotypes isolated from the herds.

Convalescent pigs are protected completely against infection with a homologous Actinobacillus pleuropneumoniae strain but incompletely against a heterologous-serotype strain.

To study whether Actinobacillus pleuropneumoniae induces a species-specific immunity, we infected pigs in the left lung with serotype 3 or 9 and after 3 weeks we infected their right lungs with serotype 9. Convalescent pigs were protected against homologous strain reinfection, but after heterologous strain reinfection the degree of protection varied. Neutralizing antibodies were not essential for protection.