Centers for Disease Control and Prevention
A transmission electron micrograph shows some of the structural details of the H3N2 flu virus that infected patients in Indiana and Pennsylvania earlier this year. The virus was formed through the reassortment of two other flu viruses.
Three children in Iowa have come down with a new type of flu virus previously linked to pigs, but this time the bug appears to have been spread by people.
The children, who live in rural Webster and Hamilton counties, did not become seriously ill, said Dr. Patricia Quinlisk, medical director for the Iowa Department of Public Health. But the detection of the virus known as swine-origin A/H3N2 in patients who hadn't had contact with animals raises concerns about potentially greater spread of a new type of flu.
"We have pretty good evidence of person-to-person spread," Quinlisk said. "None of the children or anyone around them had exposure to swine, turkeys or other sources."
Officials with the Centers for Disease Control and Prevention had previously detected seven cases of people with the new H3N2 virus that appears to have acquired a gene that may make it more transmissible from H1N1, the flu that sparked the so-called swine flu pandemic in 2009. Flu viruses often swap genetic parts. Officials say the new virus was probably formed when a pig became infected with the H3N2 virus and the H1N1 virus at the same time.
The new bug has components of human, avian, H1N1 and swine flu viruses, all mixed together in what scientists call a recombinant virus.
The first new H3N2 case was identified in a child in Indiana in July, and has been followed by cases in Pennsylvania, Maine and, now, Iowa.
In the previous cases, however, the patients either had direct exposure with pigs, or exposure to a person who'd been around pigs. In the new cases, it appears that one of the children transmitted the flu to the other two, and none of them had any animal exposure, Quinlisk said. She declined to identify the children or their ages, saying only they were younger than 18. No further cases have been identified in the past week, she said.
The Iowa cases are nothing to panic about, health officials emphasized. The H3N2 flu causes symptoms similar to the regular seasonal flu, including fever, cough, fatigue, body aches and loss of appetite.
"People need to be most concerned about the regular, everyday seasonal flu," Quinlisk said.
But Iowa health officials are now testing samples of people with flu-like illness to detect further spread of the new bug. And CDC officials have asked states across the country to be vigilant in looking for it, said Dr. Joe Bresee, the agency's influenza and epidemiology branch chief.
The current seasonal flu vaccine being offered by doctors and clinics was not developed to protect against the H3N2 virus. It contains some antigens similar to a flu virus that circulated in the 1990s, so some people who had the flu then or were vaccinated could have some immunity, but it's not clear how much, Quinlisk said. The Iowa children apparently had not been vaccinated, she added.
With the new cases, CDC officials have confirmed 31 cases in the U.S. of the new swine-origin virus since 2005, including 10 with the H3N2 virus that carries the M gene from the 2009 H1N1 virus.
The best prevention for the new flu, as with any flu, is to wash hands frequently, cover coughs and sneezes and limit spread of germs by staying home when you're sick, health officials said.