United States – A survey of wastewater samples collected from May through July across the country detected the H5N1 bird flu re-emerging— but only in locations where livestock resides.
The avian flu virus continued to infect poultry in the United States as well as herds of dairy cows, and experts have been concerned that the virus may mutate one day and spread from person to person, as reported by HealthDay.
I believe that the confirmed periods for wastewater testing between May 12 and July 13 exonerate the virus being fixed on animals.
Wastewater Testing Uncovers H5N1
According to the CDC, nine of 41 states that implemented wastewater detection of flu viruses detected sites with the H5N1 virus in samples.
However, “the nine states with H5 detections in wastewater included seven states with an HPAI A[H5N1]–infected herd reported during this period and one additional state with an infected herd reported before this period,” the agency reported.
Nine states are only in California, Colorado, Idaho, Iowa, Michigan, Minnesota, North Carolina, South Dakota, and Texas.
Human Cases and Potential Animal Sources
To the best of my knowledge, 14 cases have so far been recorded where people have contracted H5N1, which causes mere illness most of the time and usually affects persons in direct contact with infected animals, including dairy farmers.
Challenges in Identifying Virus Sources
In the new wastewater report, “two of these nine states [Colorado and Michigan] reported confirmed human cases of HPAI A(H5N1) virus infection during this time,” said the team led by Souci Louis, an investigator at the CDC’s Epidemic Intelligence Service.
“Follow-up investigations in many of these states revealed likely animal-related sources, including those related to milk processing,” the team concluded.
However, the researchers noted that wastewater testing is not perfect in identifying the source of the virus yet because, as the authors mentioned, ‘while the presence of influenza viruses in the wastewater indicates human shedding, the source cannot exclusively be identified at this time due to a lack of sensitivity of the current method. ’
Seasonal Flu Also Circulating
The same team also searched for other kinds of influenza A viruses or A subtypes of the flu virus, including H5N1. Seasonal human flu is associated with influenza A viruses, as reported by HealthDay.
The report stated that “twelve percent of the hospitals surveyed reported that at least 11 sites in four states, namely California, Illinois, Kansas, and Oregon, were passing around regular flu between people during early summer”.