Two people who are hospitalized in critical condition in mainland China have tested positive for H5N6 bird flu, raising the number of cases so far this year to 19, officials say. The spike in human cases has led to calls for increased surveillance.
The first case, a 28-year-old man from Puyang in Henan Province, developed symptoms on March 18 after exposure to live poultry, according to the Hong Kong Health Department. He was hospitalized the next day and remains in critical condition.
The other case, a 53-year-old woman from Zhenjiang City in Jiangsu Province, fell ill on March 24 after visiting a live poultry market. She was hospitalized two days later and is still in critical condition.
Other details about the cases were not released by the Chinese government, which often takes weeks or months to announce new cases.
The Chinese government disclosed last month that a 12-year-old girl and a 79-year-old man died of H5N6 bird flu in December. Both lived in Liuzhou, a city in the Guangxi region, and visited a live poultry market before falling ill.
Only 78 people have been infected with H5N6 bird flu since the first confirmed case in 2014 but most infections were diagnosed during the past year. At least 19 cases, including five deaths, have been reported so far this year.
H5N6 bird flu is known to cause severe illness in humans of all ages and has killed nearly half of those infected, including children and young adults. The outcome in most of the other cases has not been disclosed and only 8 people are known to have recovered.
There are no confirmed cases of human-to-human transmission though a woman who tested positive last year 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. The study highlighted several mutations in two recent cases of H5N6 bird flu.
Thijs Kuiken, a professor 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.
Earlier that month, the World Health Organization said the risk of human-to-human transmission remains low because H5N6 has not acquired the ability for sustained transmission between humans. However, increased surveillance is “urgently required” to better understand the rising number of human cases, the spokesperson said.