September 2nd, 2011
04:23 PM ET
You may remember "swine flu" as the 2009 H1N1 virus, which sent people out for hand sanitizer in droves and avoiding anyone who was coughing and sneezing. No one actually caught it from a pig; it's transmitted from person to person. But on Friday, the Centers for Disease Control and Prevention reports on two children who were indeed sickened by a flu virus that originated from pigs.
The CDC report "describes two cases of febrile respiratory illness caused by swine-origin influenza A (H3N2) viruses identified on August 19 and August 26." Researchers also discovered that the virus that sickened the children had a genetic component of the 2009 H1N1 flu virus that was incorrectly tagged as a swine flu. Transmission of the flu from pigs to humans is rare, but it does happen.
Don't panic, though: CDC officials say that this is a rare occurrence and that the virus is not at all likely to spread.
"It’s a biological freak. It is not a harbinger of things to come," said Dr. William Schaffner, professor and chairman of the Department of Preventive Medicine at Vanderbilt University School of Medicine.
In Indiana, a 5-year-old boy who had gotten an influenza vaccine in September started showing unusual symptoms in July: fever, cough, diarrhea, sore throat and shortness of breath. He went to a local emergency department and was discharged but returned the following day, when he was hospitalized for treatment of multiple chronic health conditions that had gotten worse. He tested positive for a swine-origin influenza A virus and has since recovered.
Although the boy hadn't had direct contact with a pig, one of his caretakers reportedly did have direct contact with swine who didn't show flu symptoms in the weeks before the boy had gotten sick. But the child's family, caretaker and other close contacts did not get sick, according to the report.
In Pennsylvania, a girl younger than 5 who had visited an agricultural fair August 16, when she had direct exposure to pigs and other animals, came down with a fever, nonproductive cough and lethargy four days later. She had also received a flu vaccine in September.
It does not appear that either child transmitted the virus to anyone else. Scientists have not found any link between the two patients. The influenza viruses they had are similar but not identical and carry a unique genetic combination never seen before. It includes bits of genetic material from the 2009 H1N1 virus, which is itself a recombination of material from other types of flu. This is not surprising: Reassortment of genetic materials from the 2009 flu virus and other swine flu viruses has been seen before, according to the report.
"We think the impact will be very marginal. There's no evidence that these viruses are spreading," Schaffner said.
There have been about 22 human cases since 2005 of influenza that originated from pigs, CDC officials said.
"These events occur rarely and are now being detected with greater frequency because we have this incredible laboratory capacity to actually diagnose these sorts of infections, which we didn't have years ago," Schaffner said.
Rather than worrying about such rare pig-human transmission events, adults and children over 6 months old should get flu vaccines to protect against more common forms of influenza in humans. A single shot now protects against standard flu and the 2009 H1N1 virus (although children 6 months to 9 years of age need two doses four or more weeks apart during their first season of vaccination.) Here's more from the CDC on flu and children.
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