By Dominique Patton

BEIJING, (Reuters) – Experts are concerned about an increase in bird flu cases in China this year. They believe that a strain previously in circulation has changed and is more dangerous to humans.

China reported 21 cases of H5N6 subtype avian influenza-related human infection in 2021, compared to five this year.

Even though the number of H7N9 cases is much smaller than in 2017, many are seriously ill. At least six people have died.

Concern is expressed by the “increase in Chinese human cases” this year. “It’s a disease that can cause high mortality,” Thijs Kuiken from the Erasmus University Medical Center in Rotterdam, who is professor of comparative pathology.

Many of the victims had been exposed to poultry. However, there have not yet been any confirmed cases of human transmission.

Further investigation is urgently required in order to fully understand both the risks and the increased spillover to the public.

A Hong Kong government statement stated that a Hunan woman aged 60 was hospitalized in critical condition on Oct. 13 for H5N6 flu.

No human H5N6-related cases have been identified, but there has not been an outbreak in China poultry since February 2020.

China is both the largest poultry producer in the world and top duck producer, both of which are reservoirs for influenza viruses.

On the increase in H5N6-related human cases, it was not possible to reach out to the Chinese Center for Disease Control and Prevention. A study that was published by the CDC last month stated that the “increasing gene diversity and geographic distribution of H5N6 poses a grave threat to both the poultry industry as well as human health.”

The Avian Influenza virus is a constant threat to wild and domestic poultry, but it rarely causes serious illness in humans. The evolution of these viruses has increased with the growth in poultry population. They could become a deadly virus and spread easily to other people, causing a pandemic.

Although the largest numbers of H5N6 cases are in Sichuan’s southwest province, there have been reports in neighboring Chongqing, Guangxi and Guangdong as well as Anhui, Hunan and Guangdong provinces.

At least 10 cases were caused by H5N8 viruses, which are very similar in genetic makeup to that virus that decimated poultry farms in Europe and killed wild birds of China last winter. The latest H5N6 infection in China could be an entirely new strain.

Kuiken said that “it could be that this variation is a bit more infectious (to people )… or there could have been more of the virus in poultry at present and that’s why there are more people getting infected.”

According to a report from China’s CDC, four of the Sichuan patients had raised chickens at home. One of the cases had purchased a live duck at a poultry market one week prior to developing symptoms.

China vaccinates chickens against avian Influenza, however, the vaccine that was used last year might not be as effective.

A request to comment was not received by the Ministry of Agriculture and Rural Affairs.

China is home to many backyard farmers, although some people prefer to get live chickens in the markets.

Guilin in Guangxi, where there were two cases of human infection in August, announced last month that the city had stopped trading live poultry in 13 urban marketplaces and will end it within a year.