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H3N2v infection continues to spread

Infections now reported in 10 states; contact with swine at agricultural fairs largely to blame, officials say.
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Sep 19, 2012

The Center for Disease Control and Prevention (CDC) continues to monitor additional cases of the H3N2 variant virus (H3N2v) infection, including the first three reported cases in Minnesota and the outbreak’s first death in Ohio. The infection’s spread has now reached 10 U.S. states totaling 296 reported cases.

Infection remains linked to direct exposure to pigs in a fair setting. Officials say no sustained community transmission has been found, as person-to-person spread of the virus is limited. The CDC continues to caution people who are 65 and older, pregnant, younger than 5 years old (especially children younger than 2 years old) and anyone with chronic medical conditions including asthma, diabetes, heart disease, weakened immune systems and neurological or neurodevelopmental conditions that they are at high risk for serious complications if infected with H3N2v.

“These people should absolutely not have contact with pigs or visit pig arenas at fairs this summer,” says Lyn Finelli of the Surveillance and Outbreak Response Team in the CDC’s Influenza Division in a release. “Anyone with a high risk factor should not only avoid pigs and pig arenas at fairs, but they should also seek prompt medical attention if they get flu-like symptoms, especially if they have pig exposure, but even in the absence of pig exposure,” Finelli says.

The CDC says symptoms of H3N2v have been consistent with seasonal influenza and include fever, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches and fatigue. The H3N2v-associated death in Ohio occurred in an older adult with multiple underlying health conditions, according to the CDC. Finelli says 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. Most of the hardest-hit have been elderly or very young.

“Something else we are looking at is schools as the school year gets under way and we move into fall and winter: the opportunities for spread of respiratory viruses like influenza increase,” says the CDC’s Joseph Bresee. “It’s possible we could see isolated cases of H3N2v infection, and even some localized outbreaks, particularly in schools or day cares.” The CDC has issued supplemental guidance for schools on H3N2v.

“It’s important to remember that this is an evolving situation that could change quickly,” Bresee says. “We’re constantly looking at our data and re-evaluating.”

Infected pigs possibly shed the influenza virus through coughs or sneezes and people nearby can breathe in the virus, the CDC says. A person can also contract the virus by touching a surface or object contaminated with the virus and then touching his or her own mouth or nose. Infected pigs present clinical signs that include fever, depression, coughing, discharge from the nose or eyes, sneezing, breathing difficulties, eye redness or inflammation and going off feed. But some pigs infected with influenza virus may show no signs at all, the CDC warns.

Last year the National Association of State Public Health Veterinarians developed the “Compendium of Measures to Prevent Disease Associated with Animals in Public Settings, 2011.” The association encourages those exposed to animals to wash hands frequently with soap and running water before and after exposure; to never eat, drink or put things into the mouth while in animal areas; and to avoid contact with animals that appear ill. Livestock owners and veterinarians who must come into contact with suspected or infected pigs should use measures such as protective clothing, gloves and masks that cover the mouth and nose.

For more information on prevention, surveillance, specimen collection, processing and testing of suspected patients, go to cdc.gov.