Scientists think the US may be missing human cases of bird flu
Do We Know Where H5N1 is Spilling Over? The Case of Dairy Workers in the U.S. Milk Supply Chain
H5N1 is in a better position than ever to move between species and spill over aggressively into humans: This bird flu virus is now thought to have been spreading among dairy cows for many months, and federal regulators have found viral fragments circulating widely in the commercial milk supply chain across the United States (though live virus has not been found).
Not only do we owe these at-risk workers better protection, but we also must do a much better job — immediately — of monitoring and testing them to ensure the virus doesn’t spread beyond our control. Otherwise, we might not find out about a significant outbreak in humans until it’s too late.
Also, notes Gray, the virus is probably much more geographically widespread in cattle than the reported cases show, “possibly spilling over much more to humans than we knew, or then we know.”
At the time the H5N1 was hitting dairy farms, some workers sought medical healthcare for flu-like symptoms, even though they were already sick, according to Gray.
The associate professor of veterinary preventive medicine at the Ohio State University says that human exposure is likely to be good based on the amount of documented cases in cows. We don’t really know.
There are 36 herds that have been affected. Federal health officials said at a conference on Wednesday that approximately 25 people had been tested for the virus in local and state health departments.
These people are in “the footprints of where the bovine detections are,” says Dr. Demetre Daskalakis, who’s with the Centers for Disease Control and Prevention, although he didn’t provide details on the actual locations.
The lack of testing early in the outbreak isn’t necessarily surprising. In places like Texas and Kansas, doctors didn’t pay much attention to bird flu until it started spreading in the spring, and took time to identify the disease as the culprit.
Jessica Leibler, an environmental epidemiologist at the Boston University School of Public Health, believes the total number of tests done on humans is low.
“If the idea was to try to identify where there was spillover from these facilities to human populations, you’d want to try to test as many workers as possible,” says Leibler, who has studied the risk of novel zoonotic influenza and animal agriculture.
The federal government has been quick to assess the safety of the dairy supply. According to the Food and Drug Administration, there was no infectious virus in about 200 samples of dairy products from around the country. Ground meat initial results are reassuring.
The true amount of the outbreak in cattle remains murky, and new federal requirements for moving cattle between states may help fill out the picture.
Mary-Margaret Fill is a deputy state epidemiologist for the Tennessee Department of Health. Instead she says there should be proactive testing.
Dr. Rodney Young says doctors in the Texas panhandle have been vigilant about any cases of influenza, particularly among those who are around livestock, but so far there are no indications of anything out of the ordinary.
The chair of the Department of Family and Community Medicine at Texas Tech’s health sciences center school in Amarillo says they have not seen many people that fit that description.
It can be difficult to measure the illness in these workers because of their location, a lack of health care, a reluctance to seek out care, and a distrust of the farmers who wave the flag.
Dairy cattle farmers currently don’t get compensated for reporting infections in their herds — unlike poultry farmers who receive indemnity payments for losses related to culling birds when they find cases, says Gingrich, executive director of the American Association of Bovine Practitioners.
Gray has managed to start collecting samples from humans and cattle at several dairy farms that recently dealt with the virus. He started a study in response to the concerns about farms being affected by the H5N1 outbreak.
They’ll look for evidence of exposure to novel influenza, including bird flu –something he’s able to pull off because of his background in this area and his guarantee that the farms will be kept anonymous in the published work.
“We know when it hits the poultry farms because the birds die, but the pigs may or may not manifest severe illness,” he says, “The virus can just churn, make many copies of itself and the probability of spilling over to those workers is much greater.”
H5N1, the deadly bird flu virus, is in a better position than ever to move between species and “spill over aggressively” to humans, an expert said. “We know when it hits the poultry farms because the birds die, but pigs may or may not manifest severe illness,” he added. ” The virus can just churn, make many copies of itself,” he further said.