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A US State Emerges as a Focal Point for Avian Influenza Outbreaks

Highly Pathogenic Avian Influenza Virus

United States: Newly disclosed wastewater monitoring results indicate that Michigan has become a critical zone for the highly pathogenic avian influenza virus, which is currently affecting poultry, dairy cows, and other mammals nationwide. Additionally, three farmworkers, including two in Michigan, have been identified as carriers of the virus.

Scientists expressed to the Free Press that they are still deciphering why all six of Michigan’s wastewater testing locations, overseen by WastewaterSCAN, exhibit significant levels of the H5 influenza A virus. This is the highest detection rate among the 38 states with sampling sites, even in areas like Jackson and Warren where no recent outbreaks among dairy cows, poultry, or humans have been reported, according to freep.com.

“There’s definitely something happening,” stated Marisa Eisenberg, an associate professor specializing in epidemiology, complex systems, and mathematics at the University of Michigan.

He added, “We’re questioning if the high activity is due to our extensive monitoring or if Michigan is genuinely a hotspot. The wastewater results indicate more H5 activity here than elsewhere.”

However, the reason behind this remains unclear. Some scientific inquiries include:

– Are there more infected dairy cattle than currently identified?

– Are asymptomatic people unknowingly carrying the virus and shedding H5 particles into the wastewater?

– Is there an alternative source elevating Michigan’s H5 wastewater detections compared to other states?

WastewaterSCAN, affiliated with Stanford University, publicly released results of H5 influenza A virus testing from 38 states and the District of Columbia dating back to May 21. As of Friday, only five states — Idaho, Iowa, Minnesota, Michigan, and Texas — reported detections in wastewater, with Michigan showing high levels at all six of its testing sites: Ann Arbor, Jackson, Jenison, Mount Pleasant, Traverse City, and Warren, as highlighted by freep.com.

Despite Jackson County not identifying infections among dairy cattle, the highest number of positive samples came from Jackson’s Wastewater Treatment Plant from May 21 to June 9. Warren’s Wastewater Treatment Plant had the second-highest detections statewide, though Macomb County also reported no known dairy cattle outbreaks.

Unraveling the H5 Virus in Wastewater

The presence of the virus in wastewater is undeniable. Richard Webby, director of the WHO Collaborating Centre for Studies on the Ecology of Influenza in Animals and Birds and a St. Jude Children’s Research Hospital faculty member, emphasized the challenge of pinpointing whether the virus stems from infected livestock waste runoff, untreated milk discharge, or other sources.

Webby hypothesized, “Is it simply milk being detected in the wastewater after passing through the digestive system? Possibly.” H5N1 viral particles, though inactive, have been found in pasteurized milk in the commercial market and could potentially be detected in wastewater samples.

Eisenberg, however, dismissed the likelihood of milk drinkers being the primary cause, noting widespread milk consumption nationwide. She is investigating whether nearby milk production plants might discharge into the areas where wastewater samples are collected.

Other hypotheses consider the possibility of septage contributions. “Are septic tank companies discharging into wastewater treatment plants?” Eisenberg questioned, suggesting the need for further exploration of local dairy farms for unrecognized infections.

Webby expressed doubt that migratory bird activity in the state, part of the Mississippi Flyway, is responsible. “Sequence analyses suggest cow-to-cow and cow-to-human transmission rather than bird-related spread,” he said. Alessandro Zulli, a postdoctoral scholar at Stanford University, concurred, noting the unlikelihood of wild birds significantly contributing to the elevated H5 detections.

Virus’s Evolution and Spread

The persistence of H5N1 raises concerns about its adaptations, especially regarding potential increased infectiousness, human-to-human transmission, resistance to antiviral drugs, or more severe illness. “This is the most active form of this virus we’ve encountered in 25 years,” Webby remarked, highlighting the virus’s unprecedented infection rates in mammals over the past three years.

The USDA’s recent epidemiological report on Michigan’s dairy and poultry outbreaks indicates the virus spreads through animal and human movement between farms. Contaminated boots, vehicles, and equipment are primary vectors, emphasizing the need for stringent biosecurity practices.

Financial Repercussions for Dairy Farms

Michigan ranks in the top ten nationally for dairy production, contributing significantly to the state’s agricultural economy. The H5N1 virus has disrupted operations at 25 dairy cattle farms across ten counties, impacting milk production and economic stability. Tim Boring, MDARD Director, noted the financial strains, with affected farms reporting reduced milk yield and increased veterinary costs.

Progress in Poultry Farms

Michigan’s commercial egg and poultry sector has also suffered, with outbreaks in 23 counties since 2022. However, recent data suggests a slowdown in new H5N1 cases among poultry, offering a glimmer of hope for the industry.

Eisenberg and her team at the University of Michigan are developing their own wastewater surveillance system to aid state health departments in tracking H5 virus activity.

In conclusion, Michigan’s elevated H5 detections in wastewater underscored the necessity for ongoing research and enhanced biosecurity measures to mitigate the virus’s spread and economic impact on the state’s agricultural sectors.

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