HONOLULU — As the number of dairy cows infected with H5N1 bird flu continues to grow and spread to multiple states in the U.S., Hawai‘i is hoping to keep the virus away.
Hawai‘i is the only U.S. state in which H5N1, also known as highly pathogenic avian influenza, has not yet been detected, according to state and federal officials — not in wild birds, domestic poultry or mammals, including cows. There have been H5N1 cases detected in wild birds in every U.S. state except Hawai‘i.
Since first reported in March, the confirmed count of H5N1 among dairy cows has grown to 152 in 12 states as of Saturday, according to the U.S. Department of Agriculture. Four U.S. dairy workers have been infected after exposure to cows.
The state Department of Health says the current risk to the general public in Hawaii is low.
But is Hawai‘i still monitoring for it?
Absolutely, across multiple pathways, according to state Epidemiologist Dr. Sarah Kemble.
State and federal agencies are keeping a close eye on H5N1 as the outbreak among cows continues to grow.
“We have a multilayered influenza monitoring strategy in place across species,” she said. “It’s not just cows. It’s people, birds and looking at what safeguards we have in place for dairy cows.”
DOH is working with the state Department of Agriculture and U.S. Centers for Disease Control and Prevention to monitor the presence of H5N1.
The state routinely tests human specimens of influenza collected from commercial labs statewide for any novel flu strains, including H5N1. The Hawai‘i State Laboratory is able to confirm H5N1 with a more specific test. The state also tracks emergency department visits for influenza.
Additionally, CDC’s wastewater monitoring program that has so far found no detections of H5N1 from the Sand Island treatment plant in Honolulu, according to Kemble.
“They’ve been testing for H5N1 for several months, with no detection of H5N1, which corroborates our low-risk status,” she said.
Since 2022, the Hawai‘i State Laboratory has tested hundreds of domestic birds, including those from O‘ahu’s largest poultry farm, those that are imported and those that appear to be ill, as part of a routine monitoring program. So far, all tests have come up negative.
The U.S. Geological Survey, meanwhile, is collecting samples from live wild birds to test for H5N1. Since 2022 more than 100 test results have been negative.
DOH is requesting USGS to increase sampling, especially of migratory birds such as the Pacific golden plover, or kolea, when they return in the fall.
Restrictions on cattle
The state Department of Agriculture in April placed a restriction on the transport of cattle from areas where H5N1 has been detected.
At that time it had been detected in only six states, but that has since doubled to 12, with the highest number of cases, so far, in Colorado, Texas, Michigan and Idaho.
Dr. Isaac Maeda, HDOA’s state veterinarian, said this was done out of an abundance of caution, with the restriction placed on all cows, not just dairy cows.
“We just wanted to be cautious about protecting cattle in the state,” Maeda said. “We took that step because there’s still a lot that has to be figured out about this particular virus in cattle. Even the transmission between cow to cow is still kind of in the air somewhat.”
On April 27 the USDA implemented a national restriction on the movement of lactating cows, and testing for H5N1 is required before any interstate movement. At the same time, Hawai‘i has not imported any dairy cows to the U.S. since H5N1 was first detected in the nation, according to state officials.
Additionally, Hawai‘i does not bring in much cattle in from the mainland.
Only 22 have been brought in so far this year, according to HDOA’s Animal Industry Division. In 2023 only 61 cattle were imported to Hawai‘i.
Hawai‘i only has one large, commercial cow dairy farm left: Cloverleaf Dairy on Hawai‘i island, which does not import cows from off-island.
HDOA already restricts the import of poultry and birds originating from areas with significant avian influenza outbreaks to Hawai‘i.
Raw milk debate
Health officials continue to recommend that residents not consume raw, unpasteurized milk in Hawai‘i.
DOH recommends against drinking unpasteurized milk because of its potential to carry and transmit pathogens such as E. coli, salmonella and other bacteria that can cause disease.
Under Hawai‘i law, according to DOH, only Grade A pasteurized milk and milk products may be sold to the final consumer or to restaurants.
In 2023, House Bill 521 sought to change this for the sale of raw milk directly from producers to consumers, but was deferred.
Advocates for the bill said there are nutritional benefits from drinking raw milk and that it would help small dairy farmers and support local agriculture.
DOH submitted lengthy testimony opposing the measure due to serious public health concerns, citing data on more than 200 outbreaks due to the consumption of raw milk and raw milk products from 1998 to 2018 in the U.S.
The testimony was submitted in 2023, before H5N1 crossed over to dairy cows, but Kemble said it adds yet another reason to avoid consumption of raw milk.
Additionally, Kemble recommends getting the influenza vaccine — not formulated for H5N1, but for other seasonal strains — when it becomes available in the fall.
This will at least prevent the possibility of getting infected with a seasonal flu strain and avian flu at the same time.
CDC, meanwhile, has influenza surveillance systems in place, and has been sequencing influenza cases in humans to monitor for H5N1.
“So far, sequencing from cases detected in people is not showing a great propensity to invade the lower respiratory tract and to cause as severe disease as we’ve seen in prior avian flu cases in other countries,” Kemble said. “It’s also not showing a great propensity to transmit person to person so far.”
DOH is working with HDOA, she said, to develop a training program and guidelines for dairy workers should avian flu be detected here in Hawai‘i. Biosafety protocols are already in place, but additional precautions are needed to protect workers.
Concerns
Some health care critics, meanwhile, are saying the CDC and USDA are not doing enough to survey H5N1 after its leap from chicken to cow to human.
They are calling for more testing and cooperation from farms in states that have detected the influenza virus in their dairy cows. Others say the U.S. should follow Finland in proactively offering farmworkers bird flu shots.
A recent editorial in Science calls on authorities to stop the H5N1 influenza in U.S. cattle with greater urgency.
“Key measures that should be initiated or intensified immediately include surveillance of all U.S. dairy farms by testing, for example, bulk milk for influenza virus RNA, implementation of strict quarantine for infected cattle, and restriction of within-state transport to stop the circulation of the virus in cows.”
Only a few states are attempting this, the article said.
“My main concern is that we’re not watching carefully enough for the transmission to and between humans,” said Tim Brown, an infection disease expert at the East-West Center in Manoa. “We should have long ago established systematic surveillance in those in the dairy industry working with infected cows, but that has received major pushback from the dairy industry and the USDA.”
Brown said concerns about business impacts should not outweigh the need to track a potentially serious emerging pathogen such as the version of H5N1 in cows.
He said authorities also have been slow to release genomic sequences that would let experts determine whether any particularly dangerous changes were occurring with potential consequences for human transmission and pathogenicity.
The U.S. and Hawai‘i need to remain vigilant.
A CDC study suggests influenza testing in U.S. health care settings can serve as an effective warning system in the event of an outbreak of a novel influenza virus with pandemic potential.
That means health care providers — in urgent care, ERs, ICUs and inpatient hospital setting — play a critical role as a first line of defense by maintaining rates of testing for influenza.
