State health officials are investigating possible sources of the H5 avian influenza virus detected for the first time in a wastewater sample from Oahu, but reassure residents that public risk remains low.
The state Department of Health said the specimen was collected Nov. 7 and that it received the result Tuesday but is unable to determine whether it is the specific subtype H5N1, also known as highly pathogenic avian influenza.
“The wastewater testing provides a signal for further investigation to determine whether this detection is H5N1-related,” said state Epidemiologist Dr. Sarah Kemble at a news conference Thursday, “and it gives us an opportunity to reinforce prevention measures, particularly among people who are at increased risk of exposure.”
Kemble said the department has collected additional wastewater samples from the plant and that the state Laboratories Division is looking into whether additional testing can reveal more specifics.
Concerns over the H5N1 outbreak are growing worldwide as it spreads from wild birds to poultry to mammals, and more recently, to dairy cows — and one pig — on the mainland, where it has also infected dozens of farmworkers.
“To date, Hawaii is the only state without H5N1 avian influenza detection in birds or animals,” Kemble reiterated Thursday. “There are no reports of human or animal H5N1 cases in Hawaii at this time. Even if H5N1 is found in our state, the overall risk to the general public in Hawaii remains low.”
She added that there is no evidence of sustained human-to-human transmission of H5N1 in the United States, and illnesses among exposed workers have been mild.
The state has been monitoring for H5N1 across multiple pathways and species in hopes of keeping it at bay, according to the department, including routine wastewater sampling. Up until Tuesday there had been no potential signs of it in wastewater.
Kemble said the detection of H5 in the isles could stem from several possibilities — it could be from wild birds flying into the state, or from people who came to Hawaii from infected areas. It could also be from agricultural animals brought into the state, but she believes this is unlikely due to Hawaii’s strict controls.
Wastewater monitoring
The U.S. Centers for Disease Control and Prevention also considers the risk of H5N1 virus infection to the public to be low, and is using flu surveillance to monitor for H5 bird flu activity in people, particularly those with animal exposures.
Wastewater monitoring, however, proves useful as an early detection tool.
CDC began monitoring wastewater across the U.S. during the COVID-19 pandemic as an early indicator of trends. Wastewater samples can be tested for levels of SARS-CoV-2, the virus that causes COVID-19, and capture their presence when shed in waste, regardless of whether patients are symptomatic.
CDC’s National Wastewater Surveillance System works with health departments to track levels of the coronavirus, along with influenza A, mpox and respiratory syncytial virus.
WastewaterSCAN, based at Stanford University, also works with the Health Department to monitor several infectious diseases at two municipal wastewater sites on Oahu: the Sand Island and Honouliuli treatment plants.
DOH said it is investigating possible sources of the H5 sample in Hawaii in partnership with federal agriculture and wildlife partners. With wastewater, however, there is no way of telling whether the source was animal or human.
The state Department of Agriculture on Wednesday encouraged poultry and bird owners to be vigilant in light of the detection.
State agriculture officials said the department’s Animal Disease Control Branch, along with two U.S. Department of Agriculture branches and the U.S. Geological Survey, have been conducting routine surveillance for the virus since 2015, when highly pathogenic avian influenza was detected along the Pacific flyway, a migratory bird path that includes Hawaii.
For decades, agriculture officials said HDOA has maintained strict bird import laws.
The department prohibits the import of birds from areas experiencing outbreaks, requires pre-entry test protocols, and embargoed bird imports through the mail. The department also has cattle import restrictions in place.
HDOA says it will distribute USDA fact sheets about avian influenza to farmers and producers, including how to prevent its spread and improve biosecurity. It has also enlisted the College of Tropical Agriculture and Human Resilience to conduct outreach and education to local farmers on H5N1.
The number of infected dairy cow herds on the mainland, meanwhile, continues to grow, with 492 cases of avian influenza now confirmed in 15 states, including Texas, Utah and California, according to the USDA.
In California the outbreak among cows began in late August and has infected nearly 300 dairy herds.
The H5N1 bird flu was also recently detected in a pig in a backyard farm in Oregon — the first detection of the virus in swine nationwide, the USDA said.
To date, CDC has counted 46 human cases of avian flu in the U.S., mostly among poultry and dairy workers.
The California Department of Health has confirmed nearly half — or 21 human cases — as of Nov. 8, mostly among workers exposed to infected cows, and has distributed protective gear to dairy farms in the state. One case in Missouri remains a mystery, as the person had no immediate, known animal exposure.
Health officials are concerned that increases in human infections could lead to more dangerous mutations of the virus.
Symptoms of bird flu in humans include eye redness, fever, cough, sore throat, vomiting and body aches or headaches.
The state Hawaii Department urges anyone who develops symptoms of avian influenza after close contact with sick or dead animals to contact its disease reporting line at 808-586-4586.
