'Bird flu unlikely to infect people'

Disinfection workers bury a plastic container filled with the culled ducks at an avian influenza-affected poultry farm in Jincheon Country, North Chungcheong Province, Tuesday. / Yonhap

By Nam Hyun-woo

With avian influenza spreading to more regions across the country, concerns are growing about the risk of the virus infecting people.

The government said Tuesday that the possibility of the H5N8 strain of bird flu infecting a person was extremely low. Twenty-eight million hens and ducks raised at infected farms have been culled so far since the outbreak.

“The H5N8 strain is unlikely to cause any immediate threat to people, though thorough disinfection is still needed to prevent further spread. It is too early to say people are completely safe,” said Professor Kim Jae-hong at Seoul National University’s College of Veterinary Medicine.

He said the virus is not transmitted by eating the meat of poultry, and humans can only be infected after very high levels of exposure.

“Farm workers and disinfection officials are more exposed to greater risks of infection, but none of them have shown any symptoms so far. Though the possibility is low, we cannot be sure and should do more studies on the H5N8 strain. The virus could infect humans and cause disease much like the H5N1 strain does,” he said.

According to the Korean Centers for Disease Control and Prevention (CDC), no human infection with H5N8 has been reported worldwide so far.

It said that there have been no reported cases of human infection from other avian influenza subtypes in Korea, such as H5N1 and H7N9, which have killed people in overseas outbreaks.

However, concern is growing over the CDC’s methods of determining human infection.

The national disease control center follows the World Health Organization’s standard when it assesses a human infection case. The WHO determines a person has been infected with avian influenza only when they show symptoms of acute respiratory disease. People who are asymptomatic, even though the virus has infiltrated their body, are not deemed cases of human infection.

When the H5N1 strain swept the country in 2003-2004 and 2006-2007, the CDC found antibodies in the blood serum of 10 people who had slaughtered chickens.

The fact that they had antibodies shows that their immune system was countering a viral infection.

“Since those 10 people showed no symptoms, they were not counted as human infection cases,” an official at the CDC said.

The Ministry of Health and Welfare explained that it was impossible to count all individuals who have had avian influenza, but shown no symptoms. “There could be large numbers of people who have been infected with the avian influenza virus but have not fallen ill,” an official said.

Professor Kim said, “In terms of bird flu in humans, an infection does not directly mean the disease develops.”