Five more people in mainland China have tested positive for H5N6 bird flu, leaving two dead and three others seriously ill, officials say. It adds to a growing number of human cases which has led to urgent calls for increased surveillance.
The Hong Kong Health Department said in a statement that it was notified about five new cases in humans in Sichuan province, Zhejiang province, and the Guangxi Autonomous Region. The cases occurred during the past few weeks and were not immediately made public by local officials.
The first case, a 75-year-old man from Luzhou in Sichuan province, fell ill on December 1 after exposure to domestic poultry. He was hospitalized four days later and died on December 12, according to the Hong Kong Health Department.
The second case, a 54-year-old man from Leshan in Sichuan province, fell ill on December 8 and was hospitalized nearly a week later. He died on December 24. He was reported to have a history of exposure to live domestic poultry.
The third case, a 51-year-old woman from Hangzhou in Zhejiang province, became ill on December 15 after exposure to live domestic poultry. She was taken to hospital on December 18 and was last reported to be in critical condition.
The other two cases occurred in Liuzhou, a city in Guangxi Autonomous Region. The Hong Kong Health Department said a 53-year-old man with a history of exposure to dead poultry fell ill on December 19 before being admitted to hospital in serious condition. A 28-year-old man from the same city fell ill on December 23 and was said to be in critical condition.
It was not immediately clear how the second man was infected.
Only 65 people have been infected with H5N6 bird flu since the first confirmed case in 2014, but more than half of those were reported during the past 6 months. The most recent case was announced on January 7, when health officials in Guangdong province said a 43-year-old woman had been hospitalized in critical condition.
Chinese officials are providing only limited information about human cases of H5N6 bird flu and it often takes weeks before cases are publicly reported to WHO. Most cases are first reported by the Hong Kong Health Department, which is closely monitoring human cases.
H5N6 bird flu is known to cause severe illness in humans of all ages and has killed nearly half of those infected, according to WHO. There are no confirmed cases of human-to-human transmission but a woman who tested positive in July 2021 denied having contact with live poultry.
“The increasing trend of human infection with avian influenza virus has become an important public health issue that cannot be ignored,” researchers said in a study published by China’s Center for Disease Control in September 2021. The study highlighted several mutations in two recent cases of H5N6 bird flu.
Thijs Kuiken, professor of comparative pathology at Erasmus University Medical Center in Rotterdam, expressed concern about the rising number of cases. “It could be that this variant is a little more infectious (to people) … or there could be more of this virus in poultry at the moment and that’s why more people are getting infected,” Kuiken told Reuters in October 2021.
Earlier that month, a WHO spokesperson said the risk of human-to-human transmission remains low because H5N6 has not acquired the ability for sustained transmission between humans, but they added that increased surveillance was “urgently required” to better understand the rising number of human cases.