Science Page: Actinobacillus pleuropneumoniae: a case of suspected lateral transmission (Part 1: diagnostics)

This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.

This week, we are sharing the first part of a report regarding an Actinobacillus pleuropneumoniae outbreak in the Midwest, across 3 systems and 5 farms.

Key points:

  • Actinobacillus pleuropneumoniae can significantly contribute to increase the costs of the growing period by increasing mortality and antimicrobial treatments.
  • All-in all-out of the affected sites accompanied with standard cleaning and disinfection procedures may suffice to ensure elimination of the bacteria.

A series of outbreaks with a sudden increase in mortality in growing pig herds located in Northwest Iowa were reported beginning in late October and early November.

Five wean-to-finish farms belonging to three different production companies were affected by a sudden onset (within 12-36 hours) of lethargy, respiratory distress and septicemia across hundreds of pigs. Clinical signs quickly spread through the sites and mortality rapidly increased with pigs having foamy bloody nasal discharge. Post-mortem examination revealed acute pleuritis and severe necrotizing bronchopneumonia. In all cases, Actinobacillus pleuropneumoniae (APP) was cultured from multiple sections of fresh lung. The APP isolate from each case was submitted to the University of Montreal for serotyping and it was confirmed to be serotype 8.

Each veterinarian intervened by rapidly mass injecting the growing herd with antibiotics suggested from the antibiotic susceptibility test together with either in-feed or water medication. Mortality rates for each site are shown on the figure below.

AAP associated mortality rates

The estimated cost of APP for each of these outbreaks was $30-$35/pig, considering treatment costs and a $2/pig cost for each 1% mortality.

Each site was completely emptied of pigs, washed and disinfected following a standard procedure. Sites were reloaded with new groups of pigs that have remained free of clinical signs associated with APP.

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