Health officials are urging renewed vigilance against avian influenza, yet some specialists are baffled as to why reports of new human cases have ceased.
Could government budget cuts be hindering case detection? Are immigrant farm workers, who have noted numerous cases in the U.S., reluctant to seek testing due to fears of deportation under the Trump administration? Or is there a natural decline in infections occurring?
“I cannot explain the absence of cases,” stated Jennifer Nuzzo, director of Brown University’s Pandemic Center. “We should consider that infections among farm workers simply haven’t been identified.”
H5N1 avian flu has been spreading widely in recent years, affecting people and livestock across the U.S., initially surfacing last year among wild birds, poultry, and other livestock globally.
In the past 14 months, 70 individuals in the U.S. have reported infections, primarily among dairy and poultry farm workers. While one person died, most of those infected experienced mild symptoms.
The most recent confirmed case, according to the Centers for Disease Control and Prevention, was in early February in Nevada, Ohio, and Wyoming.
California was a hotspot, accounting for three-quarters of the state’s avian flu cases. However, the number of tests and cases has started to decline. At least 50 people were tested each month during the latter half of 2024, but only three in March, one in April, and none so far in May. Overall, California confirmed H5N1 infections in 38 individuals, with none reported since January 14th.
Natural Causes Behind the Decrease in Avian Flu Cases
During a recent call, a CDC official highlighted that avian influenza is seasonal, with cases typically peaking in autumn and early winter—possibly tied to the migration habits of wild birds, which are the primary carriers of the virus.
This suggests that the U.S. may be experiencing a natural, possibly temporary, reduction in cases.
It is unlikely that severe human infections needing hospitalization have gone unnoticed, stated Michael Osterholm, an infectious diseases expert from the University of Minnesota.
A fragmented system has been established to monitor viruses in sewage and wastewater with limited activities recently.
While new infections are still being identified in birds and cattle and cattle, the frequency is much lower than just a few months ago.
“It’s not surprising that human cases have diminished, given that animal detections have also decreased,” a CDC statement indicated.
Are Budget Cuts Affecting Avian Flu Monitoring?
Dr. Gregory Gray expressed he was not concerned by the CDC’s lack of newly identified cases this month.
“I doubt anyone is concealing information,” remarked Gray, an infectious disease diagnostician at the University of Texas Medical Branch in Galveston.
Nevertheless, Osterholm and other experts believe that some mild infections likely remain undetected, and they are concerned that efforts to identify them are diminishing.
Resignations at the U.S. Department of Agriculture and the Food and Drug Administration’s veterinary center could hinder government surveillance for avian flu, as indicated by Keith Poursen, director of the Wisconsin Veterinary Diagnostics Institute.
Three of the 14 experts accepted offers of resignation that were delayed by the National Institutes of Animal Health Network. They were part of over 15,000 USDA staff members who accepted the offer, according to an agency spokesperson.
Dozens of staff have also been dismissed from the FDA’s veterinary investigation and response network, which dealt with animal diseases linked to contaminated pet food. Numerous cats in various states fell ill and died after consuming raw pet food contaminated with H5N1-infected poultry.
“Since Trump took office, targeted surveillance has dramatically declined,” noted Angela Rasmussen, a virologist at the University of Saskatchewan in Canada.
She speculates whether immigrant farm workers are too frightened to report exposure.
“We cannot expect individuals fearing deportation to report exposure or seek testing,” she commented.
The CDC Maintains Low Risk for the General Public
According to the CDC, the general public’s risk remains low, although it is higher for individuals working directly with poultry and cattle or coming into contact with wild birds.
Earlier this month, the Agency Review stated that there is currently a “moderate risk” that circulating strains of avian flu could result in a future pandemic, while stressing that similar concerns have been raised about other new avian flu types in the past.
Despite this, research continues.
Scientists at Texas A&M University have gathered blood samples from dairy workers across multiple states to check for signs of past H5N1 virus exposure. This year-long survey, financed by a nearly $4 million CDC grant, is expected to conclude in July.
Douphrate mentioned their strong rapport built over 20 years with dairy producers and workers, facilitating access to farms.
“We’ve seen excellent participation,” said Douphrate. “They are very supportive.”
Similar surveillance is deemed “urgently necessary” for cats, as stated by Kristen Coleman, a researcher at the University of Maryland College Park, who is investigating a new animal disease. She recently published a paper assessing infectious diseases in cats from 2004 to 2024.
The first indications of infection appeared in a barn cat that consumed raw milk from a dairy cow infected with avian flu in 2024. Thus far, the agricultural sector has identified over 120 domestic cats infected with the virus in the U.S.
Most infectious cases have been identified in deceased cats. Little is known about mild infections, if cats can recover from avian flu, or if the virus can transfer to humans.
Coleman has been collecting blood samples from American cats to detect any evidence of prior exposure to the virus, but this process is slow, and funding for the research is uncertain.
“It’s easy to downplay such situations, which is often a human tendency,” she stated. “What we really need to do is enhance our efforts.”
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Source: apnews.com