Actinobacillus pleuropneumoniae disease and serology

Actinobacillus pleuropneumoniae is a primary bacterial pathogen causing swine respiratory disease and has been described in most major swine-producing regions of the world. Preliminary diagnosis of A. pleuropneumoniae is based on clinical signs and gross pneumonic lesions. Isolating and identifying the causative bacteria confirms the diagnosis. Twelve serotypes of A. pleuropneumoniae and a number of serotype variants have been identified. Serum diagnostic tests have been developed for some of these serovars. The serological test to be implemented in a herd diagnostic effort should be determined by the herd veterinarian in consultation with the laboratory. The herd veterinarian should evaluate the advantages and disadvantages of each serological test prior to determining which test to apply in a specific herd situation. Several tests may need to be employed, as in some cases multiple serotypes are present in the same herd. Each laboratory assigns its own sensitivity and specificity to the tests they provide. Diagnostic cutoff points are set for herd evaluations and thus, serological evaluations should only be completed on a herd basis as they are not valid when applied to the individual animal. It is important to ensure that an adequate sample size of pigs is evaluated to determine the correct serological status of a swine population.