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.

Sample types and diagnostic methods for early detection of Mycoplasma hyopneumoniae

In lieu of the Science Page today, we are bringing you our most popular articles on the blog this past year: a publication by Dr. Maria Pieters, head of the MycoLab called Sample and diagnostic types for early detection of Mycoplasma hyopneumoniae.

Summary:

Mycoplasma hyopneumoniae is the causative agent enzootic pneumonia, an economically significant disease in pigs. In this study published by Drs. Pieters and Rovira from the University of Minnesota, pigs experimentally inoculated with M.hyopneumoniae were sampled 0, 2, 5, 9, 14, 21, and 28 post-inoculation.

Different sample types were compared:

  • Nasal swabs
  • Laryngeal swabs
  • Tracheobronchal lavages
  • Oral fluids
  • Serum samples

Using different diagnostic tests:

  • PCR
  • ELISA IgG anti M.hyopneumoniae
  • ELISA Ig M anti M.hyopneumoniae
  • ELISA C-reactive protein

Laryngeal swab samples tested by PCR were highly sensitive for detection of Mycoplasma hyopneumoniae in live pigs. Various commercial ELISA kits for detection of Mycoplasma hyopneumoniae antibodies showed similar sensitivity. Oral fluids showed a low sensitivity for detection of Mycoplasma hyopneumoniae in experimentally infected pigs.

Link to the full-article

NHF: Processing fluids are effective for PRRSV diagnostics

This month in the National Hog Farmer, Drs. Carles Vilalta, Juan Sanhueza, and Montse Torremorell share a project instigated by the late Dr. Bob Morrison regarding the use of processing fluids to make a PRRSV diagnosis.

The improvement of sampling and diagnostics techniques has made sampling on the farm an easier task with the use of pooled serums or oral fluids samples for example.

One of the ways to get cheaper, more sensitive and quicker techniques would be to use routine chores, such as piglet processing, since castration and tail docking are part of the regular procedures in sow farms.

The goal of this study was to evaluate the accuracy of the processing fluids (the liquid accumulated at the bottom of the pail when farmers collect tails and testicles during routine procedures) by real-time polymerase chain reaction to assess PRRSV status in a sow herd.

The key points from the studies were: