There is not enough testing for bird flu among people and animals in the US, says Dr Nirav Shah, principal deputy director of the US Centers for Disease Control and Prevention (CDC) – but he is wary of pushing the issue and damaging fragile trust among farm workers and owners.
“We would like to be doing more tests,” Shah said. “We’d like to be testing particularly not just symptomatic workers, but anyone on a farm who is exposed.”
But, Shah said, “right now we want to be in a role where we’re building trust with farms and farm workers.”
For the general public, the risk is still low, the CDC says. But the risks are elevated for agricultural workers in close contact with animals – and potentially the people around them.
The CDC is “preparing for the possibility” that the virus could evolve to spread more easily among people, according to a report published on Wednesday.
Shah encouraged the use of personal protective equipment, but stopped short at promising shots for farm workers, who are now the most at risk for getting and spreading H5N1, a highly pathogenic bird flu.
US officials announced last week that a third person tested positive – a farm worker in Michigan who worked closely with sick cows.
Unlike the previous two cases, where conjunctivitis (or “pink eye”) was the only symptom, this patient experienced respiratory symptoms typical for the flu – a cough, congestion, sore throat and watery eyes.
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Shah was quick to point out these symptoms don’t mean the virus is changing. Symptoms like these have been common in the 888 people who have tested positive for H5N1 since 2003.
“This virus, like many viruses, can present in more than one way. And for that reason, we should remain alert, not alarmed,” he said.
But having respiratory symptoms means the individual has more opportunities to pass the virus on to other people, he said, making monitoring and testing even more important than before.
Yet only 44 people have been tested in 2024, according to the CDC. While officials believe there are probably cases flying under the radar due to the lack of testing, they are closely analyzing data from influenza monitoring systems, and no red flags have been observed yet. “We have not detected any differences in markers, like emergency room visits, in areas with affected herds compared to areas without affected herds,” Shah said.
“Our influenza infrastructure is strong, and it’s notable to discuss the ways in which it differs from our Covid infrastructure,” he said. There are tests available throughout the country, there is a good vaccine candidate for this strain currently being manufactured and the virus monitoring system is already well established.
“That said, we’d love to be doing more,” he continued.
Some states are now testing the blood of dairy farm workers to see how many people have antibodies against H5N1, which would give scientists a better idea of how much the virus is circulating. “We’ve done these studies in poultry [workers] over the years. We’d like to replicate them now in dairy farm workers,” Shah said.
