Bird Flu Detected in Wastewater of Three Arizona Cities

Possible evidence of bird flu has been detected in three cities in Maricopa County, Arizona—Phoenix, Surprise and Tempe—through wastewater sampling. The Maricopa County Department of Public Health (MCDPH) released a statement on Monday reporting the detection of influenza A (H5) in these cities' wastewater. Bird flu is also known as avian influenza A (H5N1) and it is a type of influenza A (H5). "Wastewater monitoring is one of multiple tools we have to proactively monitor for avian flu in our community," said Dr. Nick Staab, assistant medical director at MCDPH, in the statement. "Given that no human cases have been identified in Maricopa County though our other disease detection methods and there is no recent documented spread of H5N1 influenza from human to human, the overall risk of avian flu to people remains low."

In the whole state of Arizona, no human cases of bird flu have been confirmed by the Centers for Disease Control and Prevention (CDC). However, two probable human cases of bird flu were reported by the Arizona Department of Health Services on December 6, linked to exposure to an infected flock of poultry in Pinal County. On December 11, MCDPH also announced the infection of several zoo animals with bird flu at Wildlife World Zoo, Litchfield Park. Testing wastewater, including sewage, can help public health officials monitor the spread of viruses and bacteria such as flu and COVID-19, even picking up cases that are symptomless and unreported.

"Testing for influenza A (H5) virus in community wastewater can provide a signal that animals or humans may be infected with the virus in the contributing community," Jonathan Yoder, deputy director of the CDC's Division of Infectious Disease Readiness and Innovation, told Newsweek."It is important to note that wastewater testing cannot tell us whether the virus particles detected in wastewater come from animals, an animal product, like milk from an infected cow, or humans. "Detections of influenza A (H5) virus in wastewater do not necessarily mean that humans in the community are infected with the virus." Dr. Nick Staab, assistant medical director at the MCDPH, told Newsweek: "Based on what we know, these findings are most likely related to recent detections reported in wild birds and other animals. There have been no detections of H5N1 in humans or in dairy cattle in Arizona." Staab said the MCDPH was "actively working to monitor and mitigate potential risks associated with avian flu," by wastewater surveillance, influenza reporting and working with other agencies to monitor people with animal exposures. He said, to avoid bird flu, residents should avoid contact with sick or dead birds, wear appropriate protective gear when in high-exposure settings, wash their hands, stay home when sick, avoid unpasteurized milk and get seasonal flu and COVID-19 vaccines "to reduce overall illness." The CDC last updated their wastewater data on December 26, based on samples from the week of Sunday, December 15, to Saturday, December 21. According to this data, influenza A (H5) was detected in 52 out of 246 sites nationwide, 49 of which were in California. California remains at the center of the U.S. bird flu outbreak, with 37 out of 66 of the country's confirmed human cases and one extra probable illness reported there. California Governor Gavin Newsom announced a state of emergency on December 18 over bird flu. Three non-Californian sites have also reported influenza A (H5) in local wastewater: Du Page County in Illinois, Wapello County in Iowa and Clark County in Nevada. Of those states, only Iowa has reported a human case of the virus, linked to exposure to infected poultry. The CDC maintains that the current public health risk of bird flu is low and there has been no reported person-to-person spread; human cases of bird flu remain connected to exposure to infected animals, such as poultry, cattle and wild birds. Out of the 66 confirmed human cases in the U.S., only one has been classed as severe: an individual who got sick in Louisiana after exposure to wild birds. But scientists are concerned that the increasing spread of the virus could lead to mutations, which could enable bird flu to be passed among humans, raising the risk of a possible bird flu pandemic.Is there a health problem that's worrying you? Do you have a question about bird flu? Let us know via health@newsweek.com. We can ask experts for advice and your story could be featured in Newsweek.Update 12/31/2024 11:02 a.m. ET: This article has been updated with comment from Jonathan Yoder, speaking on behalf of the CDC.Update 01/02/2025 5:19 a.m. ET: This article has been updated with comment from Dr. Nick Staab, speaking on behalf of the MCPHD.