Bird Flu Symptoms Explained Amid Outbreaks in Europe, Asia

Bird flu outbreaks have hit parts of Europe and Asia in recent days and weeks, prompting concern among epidemiologists.

The disease, also called avian influenza A, can spread quickly and severely amongst poultry populations. It means poultry farms and facilities must slaughter birds—sometimes tens of millions of them—to stem the spread, including healthy ones.

In bird populations the virus can cause huge numbers of fatalities with a mortality rate of around 50 percent, according to the World Organization for Animal Health (OIE).

The disease can also jump to humans. Experts have already voiced concern this year about the number of people to have come down with bird flu in China.

21 human infections of the bird flu subtype H5N6 have been reported in the country so far this year, far surpassing the 2020 total of five, news agency Reuters reported citing the World Health Organization.

"The increase in human cases in China this year is of concern," Thijs Kuiken, professor of comparative pathology at Erasmus University Medical Centre in Rotterdam, told the news agency.

Other outbreaks of bird flu types have been reported in South Korea among a poultry population of 770,000, as well as in Japan and Norway, the news agency reported citing the World Organisation for Animal Health (OIE).

While bird flu mostly affects birds, some forms can spread to humans and other animals, and it can make people very sick.

According to the U.S. Centers for Disease Control and Prevention (CDC), around 60 percent of people who have been infected with a type of bird flu called Asian H5N1 have died. Mortality with this type of bird flu has been highest in people aged 10 to 19 years old and young adults.

People tend to catch bird flu through contact with sick birds, such as by handling them or generally being near them. The virus can be inhaled through the air, but can also enter the mouth, nose, or eyes if someone touches their face with a hand that has the virus on it.

The CDC notes that some limited human-to-human infections have likely occurred in some cases. Currently, bird flu is not good at spreading between humans like COVID is.

What are the symptoms of bird flu in humans?

In humans, bird flu symptoms have ranged from mild to severe and include general flu-like symptoms such as cough, fever, and muscle ache. People can also experience conjunctivitis; nausea and diarrhea; severe respiratory illness like pneumonia and difficulty breathing; and neurologic changes like seizures, according to the CDC.

Diagnosing bird flu in people can only be done via laboratory testing, usually by collecting a swab sample from the sick person's throat.

For treatment, the CDC recommends a type of antiviral medications known as neuraminidase inhibitors. While some medications have been shown to work against bird flu, there is concern that some types of the virus may become resistant to medications, and scientists are continuing to monitor this.

Bird flu infections in humans can be prevented by avoiding exposure as most human infections occur following direct or close contact with infected poultry, the CDC notes. Vaccines for H5N1 also exist, which the U.S. has stockpiled.

People cannot get bird flu from meat or eggs if they are fully-cooked, according to the U.K.'s National Health Service, but it is possible to get it while preparing infected poultry for cooking.

Dead birds amid flu outbreak
Workers bury hundreds of dead ducks at a bird farm affected by bird flu in South Korea, in December 2003. Bird flu outbreaks that spread around farms can result in the killing of tens of millions of birds. Chung Sung-Jun/Getty