State, federal health agencies work to keep avian flu out of Hawaiian islands

State and federal agencies are keeping a close eye on H5N1, the influenza A strain associated with highly pathogenic avian influenza (HPAI) that has infected dairy cows in multiple states, as well as four people who worked closely with the infected cows.

Residents are reminded that it is safe to consume pasteurized milk or cheese, but raw milk can carry the live virus and should be avoided.

At present, Hawaiʻi is the only state in which H5N1 has not been detected.

The Hawaiʻi State Department of Health (DOH), in partnership with the state and federal Departments of Agriculture and the Centers for Disease Control and Prevention (CDC), is reinforcing long-standing efforts to detect avian influenza disease in birds, cattle, and humans in Hawaiʻi. On the human health front, this includes monitoring human influenza infections detected in the laboratory, monitoring influenza in wastewater and tracking ED visits for influenza on the Hawaiʻi Respiratory Disease Activity Summary dashboard. Further information regarding H5N1 risks in Hawaiʻi and prevention guidelines can be found on the updated DOH avian flu website.

In response to the detection of H5N1 in dairy cows on the mainland earlier this year, the Hawaiʻi Department of Agriculture (HDOA) issued an advisory on April 5 to prevent the importation of cattle from premises where H5N1 has been detected, or presence was suspected and required that cattle from affected states be examined within 72 hours of shipment and to be found free of clinical signs of H5N1. Starting April 27, the US Department of Agriculture implemented a national restriction on movement of lactating cows, which requires testing of the animals for H5N1 be performed before any interstate movement.

H5N1 is typically carried and transmitted by birds. Surveillance testing is routinely performed on domestic and wild birds and incidents of unusual morbidity and mortality are investigated to verify H5N1 is not present. HDOA’s primary focus is on domestic poultry, while the US Geological Survey (USGS) and US Department of Agriculture Wildlife Services have enhanced focus on wild birds.

Wild bird surveillance: The Hawaiʻi State Laboratory (HSL) receives and tests specimens collected by USGS from live wild birds. More than 100 test results since 2022 have been negative. DOH has requested that the USGS increase sampling, especially of migratory birds such as kōlea (Pacific Golden Plover) when they return in the fall.

Domestic poultry: Since 2022, HSL has conducted H5N1 tests on samples from hundreds of birds, including those provided by Oʻahu’s largest poultry farm as part of a routine monitoring program; birds from small or large farms in all counties that appear to be ill; and imported birds. All tests so far have been negative.

Cattle: Hawaiʻi has one dairy farm, on Hawaiʻi Island, that does not import cows from off-island. No dairy cows have been imported into Hawaiʻi in the years since H5N1 was first detected in the US Imported livestock cattle are inspected by an HDOA veterinarian; none exhibited any signs of illness that would have triggered testing.

Human influenza subtype monitoring: HSL routinely conducts subtyping on specimens provided by commercial labs that were collected from people who tested positive for influenza throughout the state, by a method that is able to presumptively identify novel subtypes, including H5N1. HSL is also able to confirm H5N1 with a more specific test. HSL has subtyped more than 620 human specimens during the current flu season to date, with no detections of H5N1.

Wastewater surveillance: WastewaterSCAN, a CDC National Wastewater Surveillance System partner, is performing continuous H5N1-specific testing (by polymerase chain reaction) on wastewater from the Sand Island treatment plant as of several months ago and has reported no detections.