Poultry farm
Representative image of a poultry farm. Mully Children's Family/Flickr

The World Health Organization (WHO) has expressed concerns after an 11-year-old girl died of a bird flu infection.

The girl, who hails from Cambodia's eastern Prey Veng province, was diagnosed with the virus last week, days after falling sick with a fever, cough, and sore throat.

Now the WHO has described the situation as "worrying" as there has been an increase in bird flu cases. "The global H5N1 situation is worrying given the wide spread of the virus in birds around the world and the increasing reports of cases in mammals, including humans," said Dr. Sylvie Briand, the director of the epidemic and pandemic preparedness and prevention division at WHO.

During the virtual press briefing held on Sunday, the agency also urged countries to increase vigilance and stay cautious.

The 11-year-old girl who died after catching the infection was found to be positive for H5N1, commonly known as bird flu. One other person also tested positive for it, following which the Cambodian authorities launched an investigation to track the source of the infection. They tested 12 people for the strain last week.

They found that these viruses were an endemic clade of bird flu circulating in the country, which essentially means that this is not a new strain and that it has been in Cambodia for many years. The strain has been identified as H5 clade

The strain has caused a significant number of deaths among wild birds and domestic poultry over the last few months.

"Yes, this is an older clade of avian influenza that has 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.

Avian flu is one of the hundreds of deadly diseases transferred between animals and humans. Most avian influenza viruses do not infect humans; however, certain strains are infectious to humans. These include H5N1, H7N3, H7N7, H7N9, and H9N2.

The most common type is the avian influenza sub-type H5N1 virus. Bird flu can infect humans who come in contact with an infected bird.

Symptoms are like most other common cases of flu, but it could turn fatal when it worsens into an acute respiratory disease. Some of the symptoms of H5N1 include cough, colds, and fever. In severe cases, the lungs can get affected too.