The US hasn't seen a human bird flu case in 3 months. Experts are
wondering why
[May 19, 2025]
By MIKE STOBBE and JONEL ALECCIA
Health officials are making a renewed call for vigilance against bird
flu, but some experts are puzzling over why reports of new human cases
have stopped.
Has the search for cases been weakened by government cuts? Are immigrant
farm workers, who have accounted for many of the U.S. cases, more afraid
to come forward for testing amid the Trump administration's deportation
push? Is it just a natural ebb in infections?
“We just don't know why there haven't been cases,” said Jennifer Nuzzo,
director of the Pandemic Center at Brown University. “I think we should
assume there are infections that are occurring in farmworkers that just
aren't being detected.”
The H5N1 bird flu has been spreading widely among wild birds, poultry
and other animals around the world for several years, and starting early
last year became a problem in people and cows in the U.S.
In the last 14 months, infections have been reported in 70 people in the
U.S. — most of them workers on dairy and poultry farms. One person died,
but most of the infected people had mild illnesses.
The most recent infections confirmed by the Centers for Disease Control
and Prevention were in early February in Nevada, Ohio and Wyoming.
California had been a hotspot, with three-quarters of the nation’s
infections in dairy cattle. But testing and cases among people have
fallen off. At least 50 people were tested each month in late 2024, but
just three people were tested in March, one in April and none in May so
far, state records show. Overall, the state has confirmed H5N1
infections in 38 people, none after Jan. 14.
The possible natural reason bird flu cases are down
During a call with U.S. doctors this month, one CDC official noted that
there is a seasonality to bird flu: Cases peak in the fall and early
winter, possibly due to the migration patterns of wild birds that are
primary spreaders of the virus.
That could mean the U.S. is experiencing a natural — maybe temporary —
decline in cases.
It's unlikely that a severe human infection, requiring hospitalization,
would go unnoticed, said Michael Osterholm, a University of Minnesota
expert on infectious diseases.
What's more, a patchwork system that monitors viruses in sewage and
wastewater has suggested limited activity recently.
New infections are still being detected in birds and cattle, but not as
frequently as several months ago.
“Given the fact that the number of animal detections has fallen
according to USDA data, it’s not surprising that human cases have
declined as well,” the CDC said in a statement.
Are government cuts affecting bird flu monitoring?
Dr. Gregory Gray said he wasn’t concerned about the CDC not identifying
new cases in months.
“I don’t think that anybody’s hiding anything,” said Gray, an infectious
disease speicialist at the University of Texas Medical Branch in
Galveston.
But Osterholm and some other experts think it's likely that at least
some milder infections are going undetected. And they worry that the
effort to find them has been eroding.
Resignations at the U.S. Department of Agriculture and the Food and Drug
Administration’s Center for Veterinary Medicine could slow the
government’s bird flu monitoring, said Keith Poulsen, director of the
Wisconsin Veterinary Diagnostic Laboratory.
Three of 14 experts accepted deferred resignation offers at the National
Animal Health Laboratory Network, which responds to disease outbreaks
with crucial diagnostic information, he said. They are among more than
15,000 USDA staff to accept the offers, an agency spokesperson said.
[to top of second column]
|
This undated electron microscopic image provided by the Centers for
Disease Control and Prevention shows two Influenza A (H5N1) virions,
a type of bird flu virus. (Cynthia Goldsmith, Jackie Katz/CDC via
AP)
 And dozens of staff were fired at
the FDA's Veterinary Laboratory Investigation and Response Network,
which investigates animal diseases caused by problems including
contaminated pet food. Cats in several states have been sickened and
died after eating raw pet food found to contain poultry infected
with H5N1.
Angela Rasmussen, a virologist at the University of Saskatchewan in
Canada, said "targeted surveillance has really dropped off
precipitously since Trump took office."
She wonders if immigrant farmworkers are too scared to come forward.
"I can’t argue with anyone who would be risking getting shipped to a
Salvadoran gulag for reporting an exposure or seeking testing,” she
said.
CDC says the risk to the general public remains low
The CDC characterizes the risk to the general public as low,
although it is higher for people who work with cattle and poultry or
who are in contact with wild birds.
Earlier this month, an agency assessment said there is a “moderate
risk” that currently circulating strains of bird flu could cause a
future pandemic, but the CDC stressed that other emerging forms of
bird flu has been similarly labeled in the past.
Still, research is continuing.
Texas A&M University scientists have collected blood samples from
dairy workers in multiple states to test for signs of past H5N1
exposure, said David Douphrate, a workplace health and safety expert
leading the project. The yearlong study is funded by a nearly $4
million grant from the CDC and is expected to conclude in July.
Douphrate said he leveraged two decades of relationships with dairy
producers and workers to gain access to the farms.
“We have had very good participation,” Douphrate said. “They have
been very willing.”
Similar surveillance is “urgently needed” among domestic cats, said
Kristen Coleman, a researcher at the University of Maryland at
College Park who studies emerging animal diseases. She recently
released a paper reviewing bird flu in infections in cats between
2004 and 2024.
Barn cats that died after drinking raw milk were one of the first
signs that dairy cows were becoming infected with bird flu in 2024.
Since then, the Agriculture Department has confirmed more than 120
domestic cats infected with the virus across the U.S.
Infections have mostly been found in cats that died. Less is known
about milder infections, whether cats can recover from bird flu — or
whether the virus can spill over into people.
Coleman has been collecting blood samples from cats across the U.S.
to see if they have evidence of previous exposure to the virus. But
the process is slow and research funding is uncertain.
“It's easy to downplay something because that's usually what humans
do,” she said. “But what we really need to be doing is ramping up.”
___
The Associated Press Health and Science Department receives support
from the Howard Hughes Medical Institute’s Science and Educational
Media Group and the Robert Wood Johnson Foundation. The AP is solely
responsible for all content.
All contents © copyright 2025 Associated Press. All rights reserved |
