An Indonesian hospital was on Monday overwhelmed with patients suffering bird flu symptoms as the disease spread further in Vietnam and Thailand reported its first case in poultry in six months.
But farm ministry officials in Japan said there was no evidence of the disease spreading there following confirmation at the weekend of a bird flu outbreak at a poultry farm in the south-west in which 3,800 chickens died.
A recent spurt of infections of the H5N1 bird flu virus, which re-emerged in Asia in late 2003, has alarmed health officials.
Four Indonesians have already died this year after a six-week lull in cases, taking the number of human deaths from bird flu in the country to 61, the highest in the world.
At Jakarta's Persahabatan hospital, where doctors were treating 9 people with bird flu symptoms, including a 5-year-old girl in intensive care, its isolation wards were overwhelmed.
"If we get more patients, we will send them to Sulianti Saroso," Muchtar Ichsan, the head of the bird flu ward, told Reuters, referring the country's main bird flu treatment centre in North Jakarta.
The patients included the son and husband of a woman who died of bird flu last week. The 18-year-old son has been confirmed to have the disease, signalling a cluster case, although tests so far on the husband show he does not have the virus.
Adding to regional worries, a senior Thai agriculture official said on Monday that 1,900 ducks had been culled in the northern province of Phitsanulok after some of the birds had tested positive for H5N1.
The case is Thailand's first in birds since last July. The last human death - the country's 17th - occurred in August.
Experts fear the H5N1 virus could mutate into a form that could spread easily between people, but there has been no evidence of human-to-human transmission of the virus so far in the latest cases.
In Vietnam, where bird flu has killed 42 of the 93 people infected since 2003, the virus appeared to be spreading fast among fowl in the country's southern Mekong Delta, threatening to engulf the major rice-growing region.