(Source-CIDRAP-University-of-Minnesota)
Researchers have discovered the presence of the H5N1 avian flu virus in wastewater samples from nine out of ten Texas cities, often at levels comparable to seasonal flu. This significant finding underscores the virus’s spread and potential public health implications.
Broad Presence in Wastewater
A team from Baylor College of Medicine and the University of Texas Health Sciences Center conducted the study, detailing their results in a new preprint. The study involved whole-virome sequencing of wastewater samples collected from March 4 to April 25. The results revealed that 19 out of 23 monitored wastewater sites had at least one detection of H5N1 Avian Flu, with the virus becoming the dominant serotype over time. The specific cities involved in the study were not disclosed, and the findings have yet to undergo peer review.
Dr. Mike Tisza, the study’s lead author and assistant professor of virology and microbiology at Baylor, noted on social media that the origins of the virus appear to be animal-related. The researchers did not observe any mutations linked to human adaptation, reinforcing the likelihood of an animal source. Tisza mentioned that the Texas network is currently the only one utilizing this wastewater sequencing technology, suggesting that H5N1 Avian Flu may also be present in wastewater elsewhere. If the virus becomes more problematic, wastewater sequencing could be crucial in identifying new adaptive mutations.
CDC’s Response and Experiments
In a May 10 update, the Centers for Disease Control and Prevention (CDC) reported monitoring over 260 individuals for H5N1 Avian Flu symptoms following exposure to infected or potentially infected animals. Of the 33 individuals who exhibited flu-like symptoms, no new human cases have been identified beyond the initial case involving a Texas dairy worker with conjunctivitis. The CDC is collaborating with several states on field epidemiologic investigations.
The CDC has initiated experiments to better understand the H5N1 virus. Last week, ferrets were experimentally infected with the virus strain that affected the Texas dairy worker to study disease severity and transmission under various contact scenarios. Ferrets are often used in flu research because their response to the virus closely mirrors that of humans. Results from these experiments are expected in about three weeks, followed by experimental infections in various cell lines.
Other Developments on H5N1 Avian Flu
The U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) reported new outbreaks of H5N1 in poultry across three states. Idaho confirmed two outbreaks in Jerome County, affecting a farm with 1,000 birds and a backyard location with 20 birds. Michigan reported an outbreak in a backyard flock in Ionia County, and California detected the virus at a live-bird market in San Francisco.
Furthermore, an expert group on animal influenza from the World Organization for Animal Health and the UN Food and Agriculture Organization, known as OFFLU, issued a statement on H5N1 in dairy cows. The B3.13 genotype of the virus, which has not been previously detected in poultry, was found in cattle. Before November 2023, this genotype had been seen in only a few wild birds and one skunk. So far, B3.13 has not been detected outside the United States, but monitoring continues.
The detection of H5N1 Avian Flu in wastewater highlights the virus’s spread and raises concerns about its transmission dynamics. Ongoing research and surveillance are crucial to understanding and mitigating the impact of this virus on both animal and human health.
