Between 10 and 13 November 2011, three children (aged 11 months, two years and three years) experienced onset of febrile respiratory illness, according to the World Health Organization (WHO). All three children had visited the same health care provider in Iowa State. None of them was admitted to hospital and all three have recovered.

Laboratory testing conducted on 18 November 2011 in the State Hygienic Laboratory at the University of Iowa showed a swine-origin triple reassortant influenza A (H3N2) (S-OtrH3N2) virus. This was confirmed by sequencing at the Centers for Disease Control and Prevention (CDC) on 20 November.

The three children attend the same day-care facility. There is an ongoing investigation and to date, no epidemiological link to swine has been identified in any of the three children. Additional investigation is currently underway to identify and characterise the illness in other day-care attendees, family members, or other contacts, and to determine any exposure to swine.

These are 16th, 17th and 18th cases of human infection with swine origin triple reassortant influenza A (H3N2) detected in the United States since 2009, and the 8th, 9th, and 10th cases reported this year.

WHO is closely following the situation with the US Government, CDC and other partners.