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Bird Flu Cases Decline: Experts Investigate Reasons
A recent decline in reported human bird flu cases has left health experts searching for answers. While the H5N1 virus continues to circulate among wild birds and poultry, new human infections have seemingly stopped. Several theories are being explored, including natural seasonal fluctuations, potential underreporting, and the impact of government cuts on surveillance efforts.
Over the past fourteen months, 70 human cases, mostly among farmworkers, were reported in the U.S., with one fatality in Louisiana. The majority of cases presented with mild symptoms.
California, a previous hotspot, has seen a dramatic drop in both testing and confirmed infections. While 50 people were tested monthly in late 2024, only three were tested in March, one in April, and none in May.
One possible explanation for the decline is the seasonal nature of bird flu. Cases typically peak in fall and early winter, coinciding with wild bird migration patterns.
This suggests the current lull could be a natural, albeit temporary, reprieve. Furthermore, wastewater surveillance indicates limited recent viral activity.
However, some experts suspect milder infections are going undetected and are concerned that surveillance efforts have weakened. Resignations at the USDA and FDA, along with staff reductions at key veterinary networks, may be hindering monitoring capabilities. Experts also question whether fears of deportation among immigrant farmworkers, who comprise a significant portion of cases, may contribute to underreporting.
Despite the decline in reported cases, the CDC maintains that the risk to the general public remains low, though higher for those working with poultry, cattle, or wild birds. However, the agency acknowledges a “moderate risk” that current bird flu strains could evolve into a pandemic threat.
Ongoing research aims to shed light on the situation. A Texas A&M University study, funded by the CDC, is examining blood samples from dairy workers for signs of past H5N1 exposure.
Preliminary findings from similar research suggest a potential undercount of infections. Further surveillance of domestic cats, which have also been infected with H5N1, is considered urgent.
While the decline in reported human cases offers a temporary respite, experts emphasize the need for continued vigilance and robust surveillance to monitor the ever-evolving threat of bird flu.