Community, social justice and wildlife conservation groups delivered a letter today urging the Centers for Disease Control and Prevention to dramatically increase its response to the outbreak of the H5N1 variant of avian influenza in U.S. dairy cattle herds.

The groups are asking the CDC to quickly ramp up testing around the deadly H5N1 variant spreading in industrial dairy herds, which has also infected at least two farm workers. They are also calling for the agency to protect farm workers and do a better job of keeping the public informed about its findings.

The request follows the spread of the disease to at least 51 dairy herds in at least nine U.S. states.

“It’s critical we learn from the mistakes of the early COVID-19 response and aggressively address industrial animal agriculture’s key role in spreading these highly contagious viruses,” said Hannah Connor, environmental health deputy director at the Center for Biological Diversity. “The CDC must ignore the pushback from big agribusiness interests and ramp up its work to protect communities and prevent the avian flu outbreak from becoming the next pandemic.”

Avian influenza, also called bird flu, refers to diseases often spread among bird species, including wild birds and domestic poultry. It is not known to have spread to cattle until recent months, leading to concerns about evolution in the spread of this disease.

Because of lax oversight of the dairy industry, it is unclear when H5N1 started circulating among cattle populations. But recent genomic analyses of U.S. Department of Agriculture data indicate that it probably began in December or January and had been spreading for four months before it was detected. But a shortage of data is hampering efforts to pin down the source, according to researchers.

Some industrial dairy operators and state officials have opposed federal efforts to track and contain the virus, telling the CDC to “back off.”

Before spreading among domestic cattle populations, the virus spread first from birds into wild mammal populations, leading to significant concerns about the disease’s threats to imperiled wildlife. Since this outbreak started, the virus has been found in federally threatened and endangered species like polar bears, grizzly bears and fishers. Outbreaks in South America have killed tens of thousands of seals and sea lions, demonstrating H5N1’s ability to cause mass mortality in mammals.

The three reported U.S. cases of avian influenza infections in humans — including the two cases connected to the most recent outbreak — have occurred on industrial agricultural operations. One occurred at a poultry operation in Colorado, the second at a dairy in Texas and the third at a dairy in Michigan. All three individuals have recovered.

Globally between 2003 and 2023, 878 humans are reported to have tested positive for the H5N1 virus. Of those, 458 deaths were reported, indicating a fatality rate of approximately 52%, according to the CDC.

“The consequences of allowing continued outbreaks of H5N1 may be severe,” said Connor. “In addition to the virus’s potential to cause pandemics in humans and wildlife, each industrial dairy operation that experiences an outbreak could put already vulnerable workers at risk and strain the food supply chain.”

Industrial animal agriculture increases the risk of an avian influenza pandemic by confining stressed animals in crowded, unhygienic conditions — the perfect breeding ground for viruses to rapidly spread, mutate and adapt. Since February 2022 more than 90 million farmed birds have been culled because of the virus.

Today’s letter was delivered to the CDC by the Center for Biological Diversity, CleanAIRE NC, Coastal Carolina Riverwatch, Mercy for Animals, North Carolina Environmental Justice Network, Socially Responsible Agriculture Project (SRAP), Southern Coalition for Social Justice, Waterkeeper Alliance and Winyah Rivers Alliance.