CDC links substantial increase in H3N2v cases with swine contact at local fairs

The U.S. Centers for Disease Control and Prevention (CDC) are reporting increasing numbers of people infected with influenza A variant (H3N2v) virus after experiencing direct or indirect contact with swine before becoming sick. The CDC issued a release Aug. 18 stating that 71 more cases were reported that week--all the cases involved contact with pigs, specifically at agricultural fairs. The virus variant was first identified in people in July 2011, with a total of 12 cases for that year. However, a substantial increase--225 cases to date--has been reported so far this year. Indiana leads the count with 138 cases followed by Ohio with 72.

Joseph Bresee, MD, of the CDC’s influenza division, expects the number of H3N2v cases to continue to rise with the high level of interaction between people and pigs in fair settings across the country. The CDC says a gene present in this form of the “swine flu” virus widely circulating in U.S. swine may make it more easily transmitted from pig to person and person to person.

However, Bresee is not alarmed by the high incidence. “Rather than focusing on case counts, it’s important to look at the kind of spread that’s taking place and the severity of illness that’s occurring," Bresee said in a CDC release. “The good news is that the main risk factor for H3N2v virus infection continues to be exposure to pigs. This H3N2v virus is not spreading readily from person to person, and illness so far has been similar to seasonal flu.”

Symptoms and signs associated with the virus include fever, cough, runny nose, sore throat and muscle aches. The CDC says everyone involved in the reported cases has recovered fully, though three people with high-risk conditions have been hospitalized. Children under 5 years old, people 65 years and older, pregnant women and people with certain chronic medical conditions (asthma, diabetes, heart disease, weakened immune system and neurological or neurodevelopmental conditions) are at high risk for serious complications if infected with influenza. The CDC recommends those at high risk avoid pigs and swine barns.

Infected pigs possibly shed the influenza virus through coughs or sneezes and people who are 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.