Bird flu, also known as avian influenza, normally spreads between sick poultry but can sometimes spread from poultry to humans. The recent detection of infections in a variety of mammals, including at a large mink farm in Spain, has raised concern among experts that the virus could evolve to spread more easily between people, and potentially trigger a pandemic
The World Health Organization said it is working with Cambodian authorities following the cases, describing the situation as worrying due to the recent rise in cases in birds and mammals.
The father of an 11-year-old girl in Cambodia who died this week after contracting bird flu has tested positive for the virus but has not displayed any major symptoms, health authorities said on Friday.
The death came amid heightened concerns over a wave of bird flu that has spread through much of the world since late 2021, posing a potential public health risk.
The girl, from a village in the southeastern province of Prey Veng, died on Wednesday at a hospital in the capital, Phnom Penh, shortly after tests confirmed she had Type A H5N1 bird flu, according to Cambodia’s Health Ministry.
She had fallen ill on February 16, and when her condition declined she was sent to the hospital with a fever as high as 39 degrees Celsius (102 degrees Fahrenheit) with coughing and throat pain.
The viruses that infected two people in Cambodia with H5N1 avian influenza have been identified as an endemic clade of bird flu circulating in the country, the U.S. Centers for Disease Control and Prevention (CDC) said.
The cases reported last week had raised concerns they were caused by a new strain of H5N1, clade 2.3.4.4b, which emerged in 2020 and has caused record numbers of deaths among wild birds and domestic poultry in recent months.
But work so far suggests this is not the case. Preliminary genetic sequencing carried out in Cambodia led its health ministry to identify the viruses as H5 clade 2.3.2.1c, which has circulated in Cambodia among birds and poultry for many years and has sporadically caused infections in people, the CDC said in a statement on Saturday.
“Yes, this is an older clade of avian influenza that had been circulating around the region for a number of years and while it has caused human infections in the past, it has not been seen to cause human-to-human transmission. However, that doesn’t mean that the threat is any less,” said Erik Karlsson, director of the National Influenza Center of Cambodia and acting head of virology at the Institut Pasteur du Cambodge, which sequenced the virus.
He added that the response needed to be coordinated and swift to prevent any further spread and to limit exposure to any common source.
An investigation into the source and to detect any additional cases is ongoing, the CDC said, adding that so far there had been no indication of person-to-person spread.
Cambodia tested at least 12 people for the H5N1 strain last week, after an 11-year-old girl died from the virus in the first known transmission to humans in the country in nearly a decade.
The victim’s father, who was part of a group the girl had been in contact with in a province east of the capital Phnom Penh, tested positive for the virus but did not exhibit any symptoms, Cambodia’s Health Minister Mam Bunheng had said in a statement on Friday. Only the girl’s case has been sequenced and the father’s case is still being worked on, Karlsson said.
The World Health Organization said it is working with Cambodian authorities following the cases, describing the situation as worrying due to the recent rise in cases in birds and mammals.
Bird flu, also known as avian influenza, normally spreads between sick poultry but can sometimes spread from poultry to humans. The recent detection of infections in a variety of mammals, including at a large mink farm in Spain, has raised concern among experts that the virus could evolve to spread more easily between people, and potentially trigger a pandemic.
Health Ministry spokesperson Ly Sovann told The Associated Press that the Cambodian father’s case is under investigation, and it was not yet known how he was infected. He has been put in isolation at a local district hospital for monitoring and treatment.
A ministry team collected samples from 12 people from the dead girl’s village known to have had direct contact with her, and laboratory tests confirmed on Friday that only her father was infected.
Health professionals have expressed concern about a wave of bird flu that has spread worldwide in the past year and a half, but consider the current risk to humans to be low.
“There is always a risk of human infection, particularly in people in close contact with poultry or wild birds, and this risk increases during times where circulation of avian influenza is particularly high, as it is now,” Jonathan Ball, professor of molecular virology at England’s University of Nottingham, said in an emailed statement.
“Thankfully, human infections are still rare, and the likelihood of onward human to human transmission very low. But this virus keeps cropping up in various mammals and this could potentially increase the possibility of further human infections. The risk to humans is still very low, but it’s important that we continue to monitor circulation of flu in both bird and mammal populations and do everything we can to reduce the number of infections seen,” Ball added.
According to the World Health Organisation, there were 56 bird flu cases in humans in Cambodia from 2003 until 2014, and 37 of them were fatal. Globally, about 870 human infections and 457 deaths have been reported to the WHO in 21 countries, for an overall case fatality rate of 53 per cent.
But the pace has slowed, and there have been about 170 infections and 50 deaths in the last seven years. In the vast majority of cases, the infected people got it directly from infected birds.
“Between 2005 and 2020, 246 million poultry died or were culled because of avian influenza,” says the World Organisation for Animal Health.
“Since October 2021, an unprecedented number of outbreaks has been reported in several regions of the world, reaching new geographical areas and causing devastating impacts on animal health and welfare,” the Paris-based agency says on its website.
The US Centres for Disease Control and Prevention agrees that the current H5N1 outbreak is mostly an animal health issue.
“However, people should avoid direct and close contact with sick or dead wild birds, poultry, and wild animals,” it warns on its website. “People should not consume uncooked or undercooked poultry or poultry products, including raw eggs. Consuming properly cooked poultry, poultry products, and eggs is safe.”