Fears of flu strains mixing

By Pongphon Sarnsamak
The Nation
June 15, 2009

Public health authorities yesterday expressed worries that the new influenza type-A (H1N1) virus could mix with the upcoming seasonal flu strain, possibly making it more dangerous to humans.

At least five more schools in Bangkok and nearby provinces as well as in the northern province of Chiang Mai would also partially or completely close starting today as the swine flu has spread.

The annual flu season runs from this month to September.

The government reported 44 fresh cases of swine flu, bringing Thailand's confirmed tally to 150.

Suankularb School, Satriwitthaya 3 School and Rajvinij School in Bangkok, and Chiang Mai Christian School will close for three days for sanitation to prevent a flu virus outbreak.

Assumption College Samrong, located in Samut Prakan, a province adjoining the capital, said it would suspend one class today after a student was found infected with the new flu.

Chiang Mai University also reported that one student, who just returned from the US, had come down with the disease.

Five more schools affected as Thai tally rises to 150

Dr Kamnuan Ungchusak, a senior health expert with the Disease Control Department, said scientists will be watching the development of A(H1N1) and seasonal flu viruses closely.

"We do not have any information yet whether it will be more virulent in humans if the virus mixes with the seasonal flu strain," he said.

According to the Public Health Ministry, 30,000 to 40,000 people suffer from the seasonal flu every year. To detect other possible mutations, Public Health Minister Witthaya Kaewparadai has ordered officials to check for avian flu and other flu viruses infecting humans for 90 days. Thailand has reported no human case of bird-flu infection during the past three years but it is possible that the new flu virus strain could mix with the seasonal flu strain during the rainy season.

Kamnuan said the Public Health Ministry would have to consider changing the medical treatment scheme for patients in case a new strain emerges.

"There's no sign of any novel influenza virus mutation yet," he said.

Jetsada Dendoungboriphan, a science lecturer at Chulalongkorn University, said a study shows that the character of the virus may not change, but its genetic material has been modified.

"There have been gradual alterations but no sign of resistance to antiviral drugs nor an increase in its severity," he said.

However, overuse of the antiviral oseltamivir drug would promote drug resistance and the new vaccine, which is now being produced, would be less effective as the virus could mutate into various forms. The World Health Organisation last Friday reported 29,669 cases in 74 countries and 145 deaths.

Dr Tawee Chotepita-yasunon, chairman of the ministry's influenza academic team, said Thailand was at level B, an outbreak in a limited circle with only 10-15 patients to a group.

But it was expected that the situation would be upgraded in one month to level C, with extensive outbreaks as seen in the US, the UK and Japan, he said.

However, the virus is not as dangerous as feared as only 10 per cent of people exposed to it fall ill and only 0.01 per cent die, mostly due to previous medical problems, he said.