Cambodia reports fatal H5N1 avian flu case

Egret in wetland

quangpraha / iStock

Cambodia today reported that an 11-year-old girl died from an H5N1 avian flu infection, according to media reports that cited the health ministry, stirring fresh concerns about the zoonotic threat from the virus, which is currently circulating in wild birds and poultry on multiple continents.

Reports of symptomatic contacts under follow-up

On Twitter, Cambodia's government said the girl from Prey Veng province died from H5N1, and it provided a link to a media report that had basic details, including that the girl was sick on Feb 16 with fever, cough, and sore throat.

The same media organization—in Khmer—said the girl had 12 contacts and that 4 of them had flulike symptoms. Agence France-Presse said officials are waiting on tests collected from dead birds found near the girl's village.

The girl's death marks Cambodia's first H5N1 case since 2014 and the world's eighth with links to the H5N1 clade that is currently circulating in poultry. The last case also involved a child, a 9-year-old girl from Ecuador who was hospitalized with a severe illness.

Some earlier cases were severe or fatal

The earlier seven cases involved people who had extensive contact with poultry, including some involved in culling operations who were screened because of their occupational exposure to the virus.

In a December 2022 risk assessment, the World Health Organization (WHO) said recent cases in China and Vietnam were linked to the clade.

The case in China involved a woman who died from her infection and whose case was reported in November. Vietnam's patient was a 5-year-old girl who was seriously ill.

Other cases point to environmental contamination

In November, the WHO weighed in on reports of asymptomatic H5N1 detections in two Spanish men who worked on the same farm where an H5N1 outbreak in poultry had been confirmed. In a new development, Spanish researchers, writing today in Eurosurveillance, said the men were involved with normal poultry operations, then helped remove dead birds and assisted with cleaning and disinfection in the wake of the outbreak.

Routine nasopharyngeal swabbing for RT-PCR testing in people at risk for exposure turned up the two H5N1 positives, which were reported to authorities, including the WHO. However, follow-up investigation found low viral loads, lack of symptoms, and negative serology, which could reflect that the positives were due to environmental contamination rather than clinical illness, the team wrote.

The researchers said false-positives can result in misclassification and negative consequences, including stigma and difficulties with communicating risk to the public. They added that the cases prompted Spain to update its swabbing protocols, noting that a human case will now be considered only if the samples were obtained under hygienic conditions.

The United States reported a similar case last April, in a Colorado culler whose only symptom was fatigue. In a recent "Ask the Expert" spotlight from the Centers for Disease Control and Prevention (CDC), Tim Uyeki, MD, MPH, chief medical officer of the CDC's influenza division, said H5N1 genetic material was only detected in the man's respiratory specimen and that he was likely not infected with the virus.

Experts still see no increased threat to humans

Uyeki said sporadic human infections aren't surprising and that an analysis of the H5N1 virus found recently at a mink farm in Spain haven't found any genetic changes that increase the virus' ability to infect people. H5N1 viruses don't currently have the ability to easily infect upper airways in humans, which would make H5N1 more transmissible.

However, he added that mink are more susceptible to H5N1, because they have two different cell receptors in their respiratory tracts.

A genetic marker was found that may make the virus more transmissible and infections more severe in mink, but Uyeki said the change isn't likely to make it easier to infect humans.

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