Second HPAI virus variant detected in Japan

In a concerning development, Japanese authorities have detected a second HPAI virus serotype in commercial poultry. 
Earlier this month, broilers at a farm on the southernmost main island of Kyushu tested positive for the H5N2 serotype, according to the official notification to the World Organisation for Animal Health (WOAH).

On the puzzles there is an inscription - Avian Influenza, on a blue background pills.
On the puzzles there is an inscription - Avian Influenza, on a blue background pills.
(SkazouD | Bigstock)

In Japan, another record has been broken. So far in the 2022-2023 HPAI season, the number of poultry culled has reached 10.08 million. Reported by Kyodo News on January 10, this is the highest number of poultry destroyed to halt the spread of the disease in the country.

In a concerning development, Japanese authorities have detected a second HPAI virus serotype in commercial poultry. 

Earlier this month, broilers at a farm on the southernmost main island of Kyushu tested positive for the H5N2 serotype, according to the official notification to the World Organisation for Animal Health (WOAH). 

Around 160 broilers died out of a flock of 12,900 birds at a farm in the Saiki city area in Oita prefecture, starting January 16. After the infection was confirmed, the rest of the flock was culled, along with two epidemiologically linked farms in the same area — 55,240 birds in total.

This is the first time this virus serotype has been detected in Japan, and these are the first HPAI cases in Oita prefecture this season. 

63 HPAI outbreaks in Japan recorded so far

Since the end of October last year, Japan’s veterinary agency has confirmed 60 HPAI outbreaks to WOAH. While this includes the H5N2 cases above, presence of the H5N1 virus serotype was been confirmed at all other infection sites.

Up to January 12, there have been 59 outbreaks linked to the H5N1 variant. These have directly impacted almost 10.95 million of the nation’s commercial poultry.  

Confirmed in the period December 26 to January 12, the 11 latest infections have involved almost 3.8 million birds. One of the outbreaks was at a premises with 445 emus, but all the others were in laying hens in flocks of up to 1.29 million birds. Affected premises were in different prefectures and regions of Japan — three on the main island, Honshu, and one on Kyushu.

Since the notification to WOAH, the Japanese agriculture ministry has confirmed outbreaks at three more farms. Again, laying hens were affected — around 582,000 birds.

They include the first cases in the prefectures of Shiga and Gunma. Located in the Honshu regions of Kansai and Kanto, respectively, these bring to 24 the number of Japan’s prefectures where HPAI has occurred so far this season. They span all eight of the country’s regions. 

In some parts of Japan, egg prices have doubled, reported NHK last week. Sharp price hikes are attributed to the unprecedented spread of avian flu in the country this season, as well as rising feed costs triggered by the war in Ukraine. HPAI has resulted in particularly heavy losses of the nation’s laying hens. 

South Korea: latest outbreaks in meat ducks, chickens

In South Korea, the HPAI season began in mid-October, according to the agriculture ministry. Since then, this source has confirmed 63 HPAI outbreaks, all linked to the H5N1 HPAI virus serotype.  

Starting January 6, the latest outbreaks have affected two flocks of meat ducks, and one each of laying hens and broiler chickens. While the two duck farms were located in the southwestern province of South Jeolla, the other affected premises were in Gyeonggi in the northwest of the country. 

Of the 63 confirmed outbreaks this season, affected have been 25 duck farms and 21 with laying hens. Cases have also been confirmed in broiler chickens, native chickens, breeding poultry, quails and ornamental birds. 

Since the start of the previous HPAI season in November 2021, South Korean authorities have notified WOAH of 102 outbreaks in commercial poultry. Directly impacted have been almost 7.88 million birds. 

In addition, the ministry reports a further eight outbreaks starting between December 26 and January 12. These have directly impacted around 477,000 poultry through mortality and culling.

Taiwan reports further HPAI cases on farms

Following a five-month hiatus, the H5N1 HPAI virus was detected again in Taiwan in mid-November of last year.

Earlier this month, the veterinary authority registered a further eight outbreaks on farms with WOAH. Starting in the period December 13-21, the outbreaks involved more than 60,000 birds in flocks, each comprising between 830 and 18,400 poultry. Affected were four farms with native chickens, and two each with meat geese and meat ducks. 

Since the start of this outbreak wave, authorities have confirmed 12 outbreaks with WOAH. Over 13,000 poultry have died, and a further 95,000 culled. 

Around the same time, the Council of Agriculture confirmed there had been five new HPAI outbreaks in Taiwan, bringing the total for the territory to 39. Of these, 25 were in chickens, 10 were on duck farms and four affected commercial geese, reported Taipei Times on December 24.

At the end of last month, more than 19,600 chickens were culled at one farm, and 16,000 more at two other premises in early January, reported Focus Taiwan. All were located in the western county of Yunlin, and presence of the H5N1 virus serotype was confirmed. 

HPAI developments elsewhere in Asia

For the first time, the H5N1 HPAI virus has been detected in the Western Visayas region of the Philippines. 

According to the WOAH notification, affected was a small farm near Roxas City in Capiz province.

Furthermore, the national veterinary agency has registered with WOAH 22 further outbreaks on the island of Luzon, and three on Mindanao. Some of the cases were confirmed in August of last year, and the most recent ones were identified in mid-December. The largest premises was a commercial farm in Bulacan province on Luzon with more than 231,000 poultry. 

Since the current HPAI wave began in the Philippines in early 2022, 226 outbreaks have been registered with WOAH. While some of the reports are incomplete, more than two million poultry have been directly impacted by these reported outbreaks.

A further outbreak has been confirmed by Israel, bringing the total notified to WOAH since mid-November last year to 10. 

In early January, testing of a breeder flock in the Southern District (Hadarom) prior to transporting eggs to a hatchery revealed the presence of the H5N1 virus. None of the 21,552 birds had shown symptoms of the infection, but all have been culled. 

Earlier this month, HPAI was confirmed in the south Indian state of Kerala, reported Press Trust of India. Presence of the H5N1 virus serotype was confirmed after around 1,800 poultry died at a state farm in Kozhikode district. 

Disease under control in two east Russia regions

Following earlier outbreaks linked to the same virus subtype, Russia’s animal health agency has declared the HPAI situation “resolved” in two regions of its Far Eastern federal district. 

These declarations followed one outbreak at a farm in Sakhalin oblast — an island to the north of Japan — in late October, and five cases in wild birds at two locations in the Khabarovsk region during November.

Four further human cases of avian flu in China

In the Western Pacific region, four additional infections with avian influenza A viruses have been registered this month with the World Health Organization (WHO). All the cases were in mainland China.

In early November of last year, a 54-year-old man became unwell. Admitted to hospital soon afterwards, he tested positive for the avian influenza A(H5N6) virus. With his condition was described as “serious,” the patient is the 83rd with a lab-confirmed infection to be reported since 2014. 

Total confirmed infections with the avian influenza A(H9N2) virus has risen to 82 since December of 2015, including two deaths. While two of the cases were reported in Cambodia, the rest have been in China.

Latest cases in China all began between mid-October and mid-November of 2022. 

One was a 58-year-old male farmer in Wugang in Hunan Province. Exposed to the virus at a live bird market, his symptoms were reported as “severe.” 

The other two cases were in young children, whose symptoms were mild. A boy in Hainan in Anhui Province was also infected at a live bird market, while the source of infection for a girl in Dingxi in Gansu Province is unknown. 

No symptoms were reported in any of the contacts of these latest patients. 

View our continuing coverage of the global avian influenza situation.

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