Health officials in Cambodia are investigating two new severe human H5N1 avian flu infections, pushing the country's total for the year to six cases.
The four earlier cases involved an older H5N1 clade that has been circulating in the country's poultry for at least 10 years. Scientists quickly posted sequences to the GISAID database, and analysis is under way to see if the two latest patients were sickened by the older clade or the newer one that is circulating globally.
Patients were neighbors in area with sick poultry
The Cambodian health ministry announced the first case on November 23 on its Facebook page. A translation posted by Avian Flu Diary (AFD), an infectious disease news blog, said the patient is a 21-year-old woman from Kampot province in the southwest.
Her symptoms began on November 19, and she was hospitalized on November 23, where she is being treated in the intensive care unit (ICU). Officials said there were dead chickens at the woman's home and in her village.
The ministry launched an investigation to look for more cases, distribute oseltamivir (Tamiflu) to people at risk, and educate people about the threat from the virus.
Two days later the ministry announced a second case, which involves a 4-year-old girl who lives next door to the first patient. In the second translated statement from AFD, officials said the girl got sick on November 23 after holding a dead chicken. She was treated with Tamiflu, hospitalized on November 25, and is also being treated in the ICU.
Older clade can cause severe disease
The four earlier cases involved the 220.127.116.11c H5N1 clade, which is different from the 18.104.22.168b clade spreading in wild birds and poultry on multiple continents, with a few spillovers to mammals, including humans, who had contact with sick birds or contaminated environments.
Infections involving the older clade are known to cause severe disease. Of the four earlier Cambodian cases, three were fatal.
After Cambodia announced its third and fourth cases in October, the US Centers for Disease Control and Prevention (CDC) said recent die-offs in Cambodia's poultry have been reported and that sporadic human H5N1 infections aren't surprising. It said it is working with Cambodian health officials and global groups to respond to the cases. "At this time, there is no indication that these two human infections with H5N1 pose a threat to the U.S. public," the CDC said.