HERD HEALTH
PIH-82
pork industry handbook
PURDUE UNIVERSITY COOPERATIVE EXTENSION SERVICE • WEST LAFAYETTE, INDIANA
Actinobacillus (Haemophilus) pleuropneumoniae
Authors
David J. Larson, Iowa State University
Gary Anderson, Lenexa, Kansas
James McKean, Iowa State University
Roy Schultz, Avoca, Iowa
Reviewers
Gary Dial, University of Minnesota
Kenneth B. Meyer, Purdue University
Martel Lee Smith, Shelly, Idaho
Barbara Straw, Cornell University
Actinobacillus pleuropneumonia (APP) is a severe, often fatal disease of growing-finishing swine. It is caused by bacterium now officially known as Actinobacillus pleuropneumoniae. This bacterium was previously named Haemophilus pleuropneumoniae, and the disease it caused was called Haemophilus pleuropneumonia (HPP). The new name, Actinobacillus will be used in this article, but the disease remains the same potentially devastating problem for pork producers.

APP is worldwide in distribution causing significant economic losses to swine industries of many countries, including Switzerland, Canada, Venezuela, Mexico, Denmark, Brazil, Germany, Japan and the United States.

APP was first recognized in the United States about 25 years ago, but has not gained prominence until recent years. The occurrence of APP in the swine-producing areas of the United States has steadily increased in the last decade. For example, the Iowa State University Veterinary Diagnostic Laboratory reported only two cases of APP in 1976, but had 100 confirmed cases in 1980 and over 500 cases in 1987. Diagnostic laboratories from other swine-producing states have also reported significant increases in numbers of APP cases diagnosed during this time.

The identification of Actinobacillus pleuropneumoniae serotypes occurring in a given geographic region is important because the protection provided by Actinobacillus pleuropneumoniae bacterin is serotype specific. Twelve distinctive serotypes of Actinobacillus pleuropneumoniae have been identified in the world and it is likely that more serotypes will be identified in the near future. Seven of those 12 serotypes (1, 3, 4, 5, 7, 8 and 9) have been identified in the United States. Serotypes 1, 3, 5 and 7 have been reported in the midwestern states with serotypes 1 and 5 being the most frequent isolates.
Clinical Signs
Sudden death of apparently healthy pigs is frequently the first sign. This sudden death generally follows a stressful period (i.e. moving, mixing, rapid weather changes, poor ventilation). Death can occur in as short a time period as 8-12 hours after the pig is exposed to Actinobacillus pleuropneumoniae. There are reports that uninfected pigs held overnight at a slaughter plant with infected pigs can develop lesions before slaughter the next morning. Pigs of all ages are susceptible, but most commonly affected are those from 40 lb. to market weight. Apparently healthy pigs may develop labored breathing and die within minutes following as small a stress as movement to a new pen within the building. Bleeding from the nose at death may be seen in some pigs but is not a consistent sign. In less severe cases, infected pigs may have abdominal breathing (thumping), high fever (104-107F), depression, and reluctance to move. Coughing may appear but is not a major clinical sign in most cases. Pigs with these milder signs may die although many will survive. These survivors may have severely damaged lungs and be poor-doing pigs. Because the organisms are spread through the air by aerosol droplets, the number affected in a group can reach 100% with death loss approaching 20-40% or more if immediate and effective treatment is not instituted.
Diagnosis
A tentative diagnosis can be made based on a history of sudden death and respiratory distress, and typical gross lesions. However, a definitive diagnosis may require culture of Actinobacillus pleuropneumoniae from a typical lesion. Culture results are particularly helpful in classifying mixed pneumonia infections.
Cooperative Extension work in Agriculture and Home Economics, state of Indiana, Purdue University and U. S. Department of Agriculture cooperating. H. A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the acts of May 8 and June 30, 1914. The Purdue University Cooperative Extension Service is an affirmative action/equal opportunitv institution.