By Jeff Mulhollem and Chuck Gill, Penn State
UNIVERSITY PARK. — Influenza outbreaks associated with swine at fairs are making headlines in the Midwest and in Pennsylvania. And these flu cases present a new twist to an old problem, according to an expert in Penn State’s College of Agricultural Sciences.
Reports in recent weeks indicated that youths working with swine at fairs in the states of Indiana and Ohio came down with a strain of the flu that had not been seen previously — a new virus. Those pigs were said to be coughing and had nasal congestion and runny noses.
The Pennsylvania cases of flu occurred among youth participants in the Huntingdon County Fair, Aug. 5-11. The youths apparently caught mild cases of flu — they had been in contact with swine — and the youths were sent home to recuperate. There were no reported hospitalizations, and there is no evidence that the new flu strain spread from person to person.
After an investigation, the Pennsylvania Department of Health reported four confirmed and six probable human cases of influenza due to a new strain of the flu, known as H3N2v. The “v” stands for variant, or new strain. This is the same virus that recently caused illness in Indiana and Ohio, mostly among children who were exhibitors at or attended agricultural fairs.
In light of these outbreaks, people visiting or exhibiting at a county fair in the coming weeks should use common sense and take steps to protect their health, especially if they are at high risk for illness, said David Wolfgang, extension veterinarian and field studies director in veterinary and biomedical sciences.
“The novel part of this is that kids at fairs have gotten the flu,” he said. “The real question is whether the kids are getting it from the pigs, or are they already sick and are sharing it with the pigs? And no one has been able to say how this variant strain of the flu got from Ohio and Indiana to central Pennsylvania so fast.
“I find this curious — and it is troubling how fast it is spreading.”
He advised fair attendees to wash their hands after visiting areas with live animals and to avoid carrying food or drink or putting things in their mouth while in these areas. Wolfgang emphasized, however, that food products from poultry and swine farms are perfectly safe, and no extra or different precautions are needed in the kitchen, beyond normal food-safety practices.
Wolfgang warned people at high risk of influenza complications to use caution and consider avoiding areas where live pigs are displayed. Those at high risk include children younger than 5 years of age, people 65 and older, pregnant women and people with certain chronic medical conditions or weakened immune systems.
Symptoms of the H3N2v flu are similar to that of seasonal influenza, including fever, coughing, fatigue and lack of appetite. Other influenza symptoms may include a runny nose, sore throat, muscle aches, eye irritation, nausea, vomiting and diarrhea.
“So far, cases of this particular strain of flu appear to be very mild in both swine and people. With variant flu viruses the concern is that you never know when there might be an additional resortment of genes, and the flu might suddenly become more virulent,” he said.
“Flu viruses are always changing. Birds, swine and people sometimes share parts of influenza viruses, and when those viruses get resorted, we get new variants, and that’s the genesis of the problem right now.”
New, variant strains of influenza typically come out of Asia, Wolfgang explained. There, potentially millions of people live in close proximity to swine and poultry in a more agrarian lifestyle. It is unusual for a variant flu strain with human, swine and bird genes to emerge in the United States, where fewer people have direct contact with pigs and birds.
Influenza is a zoonotic disease, meaning it can be passed back and forth between animals and people.
“There appear to be subclinical N3H2 viruses in some of our swine populations, and there is reason to believe that the emerging strain has human genes, bird genes and swine genes,” he said. “Because it has genes from all three groups, it is possible for this virus strain to be shared among the three groups.
“The larger group of H3N2 viruses has been around for a long time. When the viruses change slightly, it makes them easier to pass among animals and people.”
Although healthy people do occasionally die from influenza, it poses a danger primarily to elderly people, very young people or people with compromised immune systems, Wolfgang noted. But there is always the risk that a particularly virulent strain will emerge.
“The concern is that you could have reservoirs of virus that persist in poultry and swine facilities and percolate for awhile,” he said. “It doesn’t make people sick, but the virus may be changing subclinically in livestock or birds, and eventually a more virulent strain can emerge.
“That primarily happens in Asia, and when it does, at least we have a little bit of lead time to react. What scares the U.S. Centers for Disease Control and other public health professionals is that a relatively mild strain could percolate in our poultry and swine, and a more virulent strain could pop up in our country.
“That’s a bigger problem, because workers who handle the birds and swine may get sick and take the virus home, and suddenly you have a more virulent strain of flu — perhaps with higher mortality — breaking out in the middle of our population, essentially with no warning.”