State health officials are investigating possible sources of the H5 avian influenza virus detected for the first time in a wastewater sample from Oahu.

The Hawaii Department of Health said the specimen was collected last Thursday, and that it received the result on Tuesday, but that it will not be able to determine whether it is specifically the subtype H5N1, also known as highly pathogenic avian influenza.

Concerns are growing over the H5N1 outbreak worldwide as it spreads from wild birds to poultry to mammals, and more recently, to dairy cows — and one pig — in the continental U.S., where it has also infected dozens of farm workers.

“The wastewater testing provides a signal for further investigation to determine whether this detection is H5N1-related, and an opportunity to reinforce prevention measures, particularly among persons at increased risk of exposure,” health officials in a news release.

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 H5N1 avian influenza detected in birds, animals, humans or potential signs of it in wastewater in Hawaii.

Still, officials said, the overall risk to Oahu and Hawaii residents remains low as there is no evidence of sustained human-to-human transmission of H5N1 in the United States.

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.

CDC began monitoring wastewater across the nation during the COVID-19 pandemic. Wastewater samples can be tested for levels of SARS-CoV-2, the virus that causes COVID, and capture their presence when shed in waste, regardless of whether patients are symptomatic or not.

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.

Wastewater Scan, based at Stanford University, also works with Health Department to monitor several infectious diseases at two municipal wastewater sites on Oahu — the Sand Island and Honouliuli treatment plants.

State health officials said it is investigating possible sources of the H5 sample in Hawaii in partnership with federal agriculture and wildlife partners.

The Hawaii Department of Agriculture on Wednesday encouraged poultry and bird owners to be vigilant in light of the detection.

State agriculture officals 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.

The number of infected dairy cow herds in the continental U.S., 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, according to the USDA.

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 in the state as of Nov. 8 — mostly among workers exposed to infected cows. CDPH has distributed protective gear to dairy farms and workers in the state.

Symptoms of bird flu in humans include eye redness, fever, cough, sore throat, vomiting, and body aches or headaches.

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Best practices

>> Do not touch birds, livestock, or wild animals that are sick or dead without personal protective equipment.

>> Report sick pets to their veterinarian.

>> Contact the Animal Industry Division at Hawaii Department of Agriculture at 808-483-7106, Monday to Friday from 7:45 a.m. to 4:30 p.m., or 808-837-8092 during non-business hours and holidays to report multiple or unusual illnesses or deaths in poultry, livestock, or wild birds or animals.

>> Do not touch or consume raw milk or raw milk products, especially from animals with confirmed or suspected avian influenza infection. Pasteurized milk products are safe.

>> Contact the Department of Health immediately at 808-586-4586 if you develop symptoms of avian influenza and have been in close contact with sick or dead animals.

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Source: Hawaii Department of Health