Japan on high alert as avian flu rages across the country and heads north

Hardly a week passes by without news of a poultry farm in Japan being hit by an avian flu outbreak.

Since the start of the bird flu season in October, 80 farms in 26 prefectures have been affected, forcing a record 16.1 million chickens to be culled as of Wednesday, according to the agriculture ministry.

Just this month, four outbreaks were reported at egg farms in Fukuoka, Niigata and Iwate prefectures, and officials in the Tohoku region and Hokkaido are on high alert as migratory birds carrying the virus are now making their way toward the northern parts of the country.

Japan is one of many countries struggling with egg shortages and prices have soared as a result. But how worried should people be about other impacts of bird flu, including potential dangers to human health? Here’s what you need to know about avian flu in Japan.

Are avian flu outbreaks rare in Japan?

No. Japan had its first bird flu outbreak caused by H5N1, a highly infectious and pathogenic subtype of the influenza A virus, in 2004. Since then, it has had outbreaks periodically. The last big outbreak took place in 2020-2021, when 9.87 million birds were culled.

The origin of the current outbreaks can be traced to the H5N1 virus found at a goose farm in Guangdong Province of China in 1996. This virus spread to Shandong Province in 2003, then caused a massive outbreak in South Korea later that year, eventually reaching Japan in 2004, according to a 2005 report by the National Institute of Infectious Diseases.

What's special about the current spread of the disease?

The nation’s bird flu season normally starts with the arrival of migratory birds from the Russian Far East and northern China in November and lasts until they depart around May. For the current season, however, Sept. 25 marked the earliest report of a wild bird infection on record when a dead peregrine falcon in Isehara, Kanagawa Prefecture, was confirmed to be infected with the H5N1 virus. The first outbreak in the poultry industry occurred on Oct. 28 at an egg farm in Okayama Prefecture.

The outbreaks this year are also geographically diverse and affecting prefectures that had previously never reported infections. The agriculture ministry attributes the earliest arrival of the bird flu season to increasing virus levels in the environment.

What kind of prevention and control measures have been taken at poultry farms?

Amid record outbreaks, the ministry issued a notice in November reminding poultry farmers to follow existing prevention protocols. They include frequent disinfection measures and changing boots that farmers wear, as they can carry contaminated bird droppings. Farm buildings and bird cages near ponds where wild or migrant birds gather or fly by must also be disinfected, while farm operators are asked to identify and close off spaces that wild cats, weasels and mice could enter.

Once there’s an outbreak at a farm, the government orders a series of containment measures based on the Law on the Prevention of Infectious Diseases in Livestock. They include culling the farm’s entire flock, burning or burying the corpses, and disinfecting all of the farm equipment used.

In addition, an area within a 3 kilometer radius from the farm is designated as a movement restriction zone, from where the shipment of chickens and eggs is prohibited. Officials also disinfect the surrounding roads and drain water out from nearby reservoirs to reduce the risks of wild birds further spreading the virus.

While outbreaks remain high, Japan has been successful at keeping infections under control, thanks to a system in which the government compensates farmers for their losses, said Yoshihiro Sakoda, a professor of veterinary medicine at Hokkaido University. That’s not the case in some developing countries where governments don’t have the authority or resources to take such strong measures, he said.

Can vaccines help contain avian flu?

With a virus like the one that causes COVID-19, vaccinations are considered essential to protect individuals and the community. But as far as avian flu is concerned, vaccinations of poultry are “the last of last resorts,” Sakoda said.

Avian flu vaccines are not effective enough to stem infections, he said. Sakoda is critical of the use of vaccines in some countries without thorough containment measures, saying they are “making infections look like they don’t exist” by having sick poultry barely survive — and making them available for consumption.

“In Japan, while outbreaks are happening, both researchers and government officials can say with confidence that farms where outbreaks have not been reported are free of the virus,” he said. “If you start using vaccines, however, they would make outbreaks harder to spot. (In such scenarios) if I were asked whether the eggs and chicken meat (at supermarkets) are virus-free, I would only be able to say, ‘maybe.’”

Is it safe to eat chicken and eggs in Japan?

The government says eggs and chickens sold in Japan are safe.

According to the Food Safety Commission, all domestic eggs and chickens are disinfected with sodium hypochlorite before being sold. Imported eggs and chicken are safe, too, as the government halts imports of such products from countries where there is an outbreak.

It's also important to note that the virus can't be transmitted by ingesting fully cooked chicken and eggs from infected birds.

How can people get infected with bird flu?

In late February, Cambodia reported two human cases, including an 11-year-old girl who died, and her father, who had no symptoms, sparking fears of human-to-human transmission. But the two were both “infected from birds in their village” and no such transmission was found, according to the Cambodian Communicative Disease Control.

It is extremely rare for humans to get bird flu, but when they do they usually get it by coming into direct contact with infected birds. From 2003 to February of this year, a total of 873 human cases of H5N1 and 458 deaths have been reported from 21 countries, according to the World Health Organization. Through March 9, 240 have been reported in East and Southeast Asia alone — 127 in Vietnam, 56 in Cambodia, 54 in China and two in Laos. There were none from Japan.

What other preventive measures can be taken?

To better grasp the spread of the virus, Japan should step up surveillance of wild birds, said Sachiko Moriguchi, a postdoctoral researcher at Nippon Veterinary and Life Science University, noting that most of the reports come from examining dead birds.

Since the discovery of the dead falcon in September, over 200 incidents of bird deaths have been confirmed in which the birds — ranging from cranes to ducks to crows — have tested positive for H5N1, according to the Environment Ministry.

Japan’s approach contrasts to the one in the U.S., where officials have more freedom to decide on the number and kind of bird species to test. They do so by capturing healthy-looking live birds, testing for the virus and then releasing them, in addition to testing dead birds collected from hunters, Moriguchi said.

“Species of birds confirmed to be infected through deaths are vulnerable to the virus, so it is likely they can't spread the virus as much as those that are alive and are spreading it,” she said.

What can people do?

Moriguchi says people should not touch dead or frail birds, which could be infected with avian flu, and report them swiftly to prefectural authorities. By collecting such birds, the disease’s spread to scavengers such as crows, raptorial species and mammals can be prevented.

Sakoda urges pet owners to be aware of risks in case their pets come into contact with dead birds or raccoons, and to take them to a veterinarian when and if they do.

He added that the avian flu season in Japan will continue for another two months or so, but it won’t stay forever. Infections will subside when migratory birds, which are now passing through Tohoku and Hokkaido, fly out of the country, he said.