Close contract with pigs at an Indiana (USA) county fair held from July 8-14, 2012, led to identification of respiratory illness among swine and people.
On July 16, specimens were collected from four persons with respiratory illness; two had become ill on July 12 and sought care at an emergency department, and two who were identified as part of the subsequent public health investigation. All four persons were swine exhibitors or family members of swine exhibitors and had close contact with swine.
On July 18, reverse transcription–polymerase chain reaction testing (RT PCR) at the Indiana State Department of Health laboratory identified suspected influenza A (H3N2) variant (H3N2v) virus in all four specimens. On July 21, partial genome sequencing was carried out at the Centers for Disease Control and Prevention (CDC; Atlanta, GA, USA). CDC confirmed H3N2v virus with the influenza A (H1N1) pdm09 virus M gene; the viruses detected in the four specimens are similar to 12 viruses detected in 2011 and one detected earlier this year.
None of the four persons was hospitalized, and all have fully recovered. There was no word on the subsequent health of the pigs.
The four human cases of H3N2v virus were confirmed by the Centers for Disease Control and Prevention (CDC; Atlanta, GA, USA). The influenza A (H1N1) pdm09 virus M gene was identified by CDC. The viruses are similar to 12 cases identified in 2011 and 1 detected earlier this year
Respiratory specimens from a sample of 12 pigs at the fair were positive for influenza A (H3N2) virus. Preliminary genetic analysis has shown a very high level of similarity between the gene sequences of H3N2v viruses from humans and the H3N2 viruses from pigs, the CDC reported.
The CDC recommends that clinicians who suspect influenza in patients with recent exposure to pigs should obtain nasopharyngeal swab or aspirate in viral transport medium, and contact their state or local health department and request diagnosis at a state public health laboratory. For more information, plese see CDC's: H3N2v website.
Health officials advise that persons who raise pigs or come into close contact with them at fairs or other such summer venues should be aware of the potential risk for influenza transmission between swine and humans. For a full report of swine flu in the US, please see: Morbidity and Mortality Weekly Report (MMWR)
Centers for Disease Control and Prevention