10 August 2012
Human cases of variant influenza A (H3N2) in the United States
On 3 August 2012, the United States Centers for Disease Control and Prevention (CDC) released an advisory regarding an increased number of cases of variant swine origin influenza A (H3N2) virus (A(H3N2)v) since July 2012 .
Since July 2011, 146 cases of influenza A (H3N2)v have been reported in the United States (US) . Cases have been reported in Indiana, Ohio, Illinois and Hawaii. Indiana has reported most cases and, as at 9 August, over 110 cases have been identified .
Influenza A (H3N2)v is a swine origin virus that is circulating in pigs in the USA. The first human cases associated with the current outbreak were detected in July 2012; all cases for which information is available have had contact with pigs. In the cases reported from Indiana and Ohio, this contact occurred at country fairs which are commonplace in the summer and early autumn months. No severe illness or deaths have been reported.
Advice for travellers
Influenza A (H3N2)v virus infection causes illness similar to seasonal influenza including fever, cough, myalgia and headache. Individuals at increased risk of severe illness include those with underlying medical conditions such as asthma or diabetes, infants under five years of age, adults over 65 years and pregnant women.
Although the risk of influenza A(H3N2)v infection is low for travellers to the US, they are advised to follow the guidance from the CDC.
Travellers visiting country fairs or agricultural events should wash their hands after contact with livestock and avoid eating and drinking whilst in animal areas. Those at increased risk of severe illness should consider avoiding contact with pigs or swine barns.
Health professionals should be alert for travellers returning from the US with an influenza-like illness who have had contact with pigs. Such travellers should be investigated further in accordance with guidance from their local Health Protection Unit.
1. United States Centers for Disease Control and Prevention. Increase in influenza A H3N2v virus infections in three U.S. states. 3 August 2012. [Accessed 10 August 2012]. Available at: http://www.bt.cdc.gov/HAN/han00325.asp
2. United States Centers for Disease Control and Prevention. Information on influenza A (H3N2) variant viruses (H3N2). 9 August 2012. [Accessed 10 August 2012]. Available at: http://www.cdc.gov/flu/swineflu/influenza-variant-viruses-h3n2v.htm