4 September 2012

Human cases of swine-origin influenza A(H3N2)v in the United States - Update

On 31 August 2012, the US Centres for Disease Control and Prevention (CDC) confirmed the first death associated with swine-origin influenza A(H3N2)v in a 61-year-old female from Madison County, Ohio. The patient had multiple underlying health conditions and reportedly had direct exposure to pigs at the Ross County fair [1].

As of 31 August 2012, there have been 289 human cases of swine-origin influenza A(H3N2)v virus reported in the United States (US) since it was first identified there in humans in July 2011 [2].

Thirteen states have reported cases infected with influenza A(H3N2v):  Hawaii, Illinois, Indiana, Iowa, Maine, Maryland, Michigan, Minnesota, Ohio, Pennsylvania, Utah, West Virginia, Wisconsin. Most cases have occurred in Indiana (138 cases) and Ohio (101 cases) [2].

The majority of the persons infected had contact with swine or attended an agricultural fair where swine were present. So far more than 90 percent of cases have occurred in people who are exhibiting or helping to exhibit pigs, or who are family members of these people. While limited person-to-person spread of this virus has been detected and is likely to continue to occur sporadically, no sustained community transmission has been found [3-4].The US CDC is monitoring the situation and working with states to respond to these evolving outbreaks.

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.

This virus has not been identified in pigs or humans in the UK [5].

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.

References

1. Ohio Department of Health. Ohio Documents First H3N2v-Associated Death. 31 August 2012. [Accessed 4 September 2012]. Available at:

http://www.odh.ohio.gov/~/media/ODH/ASSETS/Files/news

/83112%20First%20H3N2v%20Fatality%20news%20

release.ashx

2. United States Centers for Disease Control and Prevention. [Accessed 4 September 2012]. Available at: http://www.cdc.gov/flu/swineflu/h3n2v-outbreak.htm

3. United States Centers for Disease Control and Prevention. Situation Summary on Influenza A (H3N2) Variant Viruses (“H3N2v”). 31 August 2012. [Accessed 4 September 2012]. Available at:

http://www.cdc.gov/flu/swineflu/h3n2v-situation.htm#assessment

4. Worl Health Organization. Influenza. Seasonal Influena updates. Epidemiological influenza surveillance update 167. 31 August 2012. [Accessed 3 September 2012]. Available at:

http://www.who.int/influenza/surveillance_monitoring/updates/

2012_08_31_surveillance_update_167.pdf

5. Health Protection Agency. Update on new swine flu in the US. 21 August 2012. [Accessed 4 September 2012]. Available at: www.hpa.org.uk/NewsCentre/NationalPressReleases/2012

PressReleases/120821UpdateonnewswinefluintheUS/

Links

Health Protection Agency – Influenza

U.S. Centers for Disease Control and Prevention: AH3N2v case count