Sequencing implicates older H5N1 avian flu clade in Cambodia's latest case and death

H5N1 virus

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In an update on two recent H5N1 avian flu cases in Cambodia, the World Health Organization (WHO) said the adult woman has died from her infection and that genetic sequencing suggests both infections, like four earlier ones this year, involved the older Asian clade——that has been circulating in the country's poultry for at least a decade.

Last week, the country's health ministry had reported the infections in patients from the same village in Kampot province. The first was a 21-year-old woman, and the second was a 4-year-old girl.

One patient died, another treated in isolation

The WHO said the woman died on November 26 after a 4-day hospitalization. Meanwhile, the girl is isolated in the hospital, where she is receiving treatment.

An epidemiologic investigation found that both patients had been exposed to backyard birds over the past month that were sick or dead. No other links between the patients were found, other than that they are from the same village. "In these two cases, while human-to-human transmission cannot be ruled out, it is likely there were separate exposures to the viruses from sick and dead chickens," the WHO said.

Cambodia's agriculture ministry yesterday reported a highly pathogenic H5N1 avian flu outbreak in poultry from the village where the woman and girl lived, according to a notification from the World Organization for Animal Health. The virus killed 105 of 332 susceptible poultry.

Lab analysis shows that the virus from the patients is similar to the H5 clade virus that has been circulating in Cambodia and Southeast Asia since 2013-2014. The clade is different than the one spreading globally in wild birds and poultry, with sporadic spillovers into mammals, including people.

The WHO said sequencing suggests the virus from the patients is most closely related to the viruses reported from two human cases in October.

More cases expected in at-risk area

The older clade is known to cause severe or fatal infections. Of the six Cambodian cases reported this year, four have been fatal.

Though the virus doesn't easily infect people, it continues to spread in poultry, especially in rural Cambodia, where the situation poses an ongoing risk of sporadic infections in humans.

Since 2003, Cambodia has reported 62 H5N1 infections, 41 of them fatal.

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