While the rate of new HPAI outbreaks in Japan continues to slow, spread of the disease continues.
Based on official notifications to the World Organisation for Animal Health (WOAH), almost 17 million of the country’s poultry have been directly impacted by the viral infection in the current “season,” which began in October of last year.
Suffering particularly heavy losses through mortality and culling has been the nation’s egg industry. This has led to sharp increases in egg prices in Japan.
In a recent report, NHK puts the number of poultry culled this season in Japan at around 17 million. The total includes around 9% on the nation’s laying hens.
In a survey of the 26 prefectures where HPAI outbreaks have occurred, 16 reported challenges disposing of the culled populations appropriately. Many prepared sites were subsequently found to be unsuitable in this country where the land area is limited by geography.
According to a professor at Hokkaido University, Japan should consider alternative methods of HPAI control, such as carcass incineration and reducing the number of birds culled.
Japan confirms 83 HPAI outbreaks in poultry this season
Since the nation’s first cases of HPAI were confirmed at the end of October 2022, the veterinary authority had registered 82 outbreaks with WOAH up to the end of March.
In the last week of that month, presence of the H5N1 HPAI virus serotype was confirmed in two layer flocks in northern Japan. Affected were 558,000 hens at a farm in Chitose city in Hokkaido, and 327,300 in Aomori (a prefecture in northeastern Honshu).
These brought to around 16.9 million the number of poultry directly affected by this virus so far, including more than 11,000 mortalities. The remaining birds have been culled.
Since the WOAH notification, Japan’s agriculture ministry has confirmed one further outbreak. This affected another layer flock in Chitose — comprising 350,000 birds — along with an epidemiologically linked flock of 40,000 chickens in the same area.
As well as these 82 outbreaks linked to the H5N1 serotype, the H5N2 variant was detected on a broiler farm in southern Japan in January of this year.
Up to the end of February, 1,295 wild birds have also tested positive for the H5N1 virus at 181 Japanese locations, according to WOAH notifications.
Latest South Korean outbreak on duck farm
Around 15,000 meat ducks were involved in the latest HPAI outbreak, according to South Korea’s agriculture ministry. In a report earlier this week, the infection was confirmed at a premises in South Jeolla following reports of elevated mortality in the flock. The province is located in the southwest of the country.
According to the ministry, this brought the number of outbreaks in South Korea since October 2022 to 72. Among those premises to be affected have been 27 with meat ducks and 23 with laying hens.
Between October 2021 and the end of 2022, authorities had notified WOAH of 102 outbreaks of HPAI linked to the H5N1 virus in poultry flocks. These directly impacted almost 7.9 million birds.
Avian flu situation in South Asia
For the first time since June 2019, the H5N1 HPAI virus has been detected in Bhutan, according to the WOAH report.
Fomites and contact with wild birds were blamed for infecting a backyard flock of 41 poultry. In mid-March, 35 of the birds died at a premises in Samtse, a district in the southwest of the kingdom.
In Nepal, two further outbreaks have been registered with WOAH, bringing the country’s total since January to 13, and the poultry population affected to more than 64,000.
As in all the previous outbreaks in this disease series, the farms were located in Bagmati Pradesh in Nepal’s Central Development Region. All have been near to the capital, Kathmandu.
In India, Mongabay reported a shortage of eggs at the end of last month. This was attributed, in part, to avian influenza outbreaks.
The nation’s only HPAI outbreaks reported to WOAH so far this year were at a government-run farm in the eastern state of Jharkhand, and previously in ducks in Kerala in southern India.
Taiwan reports further HPAI outbreaks
Latest notification from Taiwan’s veterinary authority to WOAH outlines six new HPAI outbreaks in commercial poultry.
Between February 23 and March 13, presence of the H5N1 HPAI virus was confirmed in three commercial flocks of native chickens, two of laying hens and one of chicks. The premises were located in four different counties.
With these latest outbreaks, Taiwan’s total since November of last year has reached 43, directly impacting more than 964,000 commercial poultry.
In late March, the Council of Agriculture minister announced that avian influenza has been brought under control in Taiwan. This is according to a Taiwan News report, which also covered the territory’s imports of 60 million eggs during April and May to cover a shortage in domestic production.
Furthermore, the animal health agency has also registered H5N1 virus infections in a wild bird found dead in Kaohsiung city, and around 500 native chickens found dumped in a drainage ditch in Changhua county.
Further human case of avian influenza in China
In the Western Pacific region, one additional infection with avian influenza A virus of avian origin has been registered with the World Health Organization (WHO).
Found to be infected with the avian influenza A(H5N1) virus was a female farmer in China’s Anhui province. Her symptoms began at the end of January, and she was admitted to a hospital on February 4. The patient was reported still to be undergoing treatment at the end of March.
Previously, the patient had contact with backyard poultry, and sampling of the birds and environment showed the presence of the same virus serotype.View our continuing coverage of the global avian influenza situation.