A 6-year-old Thai boy became Asia's seventh confirmed bird flu fatality, and Pakistan on Monday joined the list of countries affected by the disease that has sparked mass chicken culls across the region.

The World Health Organization (search) pleaded Monday with the global scientific community to accelerate the search for a cure. Attempts to tackle the virus are being frustrated by its fast rate of mutation as well as its spread across at least eight countries.

Pakistan said it had detected a form of bird flu in its chicken population. The commissioner for livestock husbandry said it was not a strain of bird flu that can spread to humans — something that has happened in other parts of Asia.

"We have confirmed this. The strand that jumps to humans is not in them," commissioner Rafaqat Hussain Raja said.

Faizullah Kakar, an official at the WHO office in Pakistan, said it had no confirmation of an outbreak of bird flu in the South Asian nation.

Laos, meanwhile, fears it might also be hit by the bird flu and is awaiting test results on the nature of an illness killing its fowl, the U.N. Food and Agriculture Organization (search) said.

Other Asian governments frantically slaughtered chicken flocks in a desperate bid to contain the disease, as well as the growing political fallout from accusations that officials in two countries — Thailand and Indonesia — initially covered up outbreaks.

Dr. Prasert Phongcharoen, a WHO adviser and viral disease expert, urged caution in the disposal of the chicken carcasses. If infected chickens are thrown in rivers, "the virus could spread to open pig farms and this could result in transmission from pigs to humans," he said.

Officials in Bangkok said they were investigating whether the virus might be being carried by migratory birds.

The Thai boy, Captan Boonmanut, became infected after he played with chickens in his village a in the central Kanchanaburi province (search). He died Sunday night in a Bangkok hospital, Thailand's first confirmed death from the virus.

Six people have died in neighboring Vietnam and Thai officials are trying to determine whether bird flu was also the cause of last week's death of a 56-year-old man who had bred fighting cocks.

Thailand's Public Health Ministry also said Monday that four other people suspected of having bird flu had died in the northern Sukhothai province, but it was awaiting lab results to confirm whether they had the avian influenza virus.

The WHO said a search for a cure had been set back because the virus had mutated. A previous strain detected in Hong Kong in 1997 can no longer be used as the key to producing a vaccine. It said an international effort was needed.

Scientists believe people get the disease through contact with sick birds. Although there has been no evidence yet of human-to-human transmission, health officials are concerned it might mutate further and link with regular influenza to create a form that could be transmitted from person to person, triggering the next human flu pandemic.

"This is now spreading too quickly for anybody to ignore it," said WHO spokesman Peter Cordingley in Manila.

So far eight countries have reported bird flu — Thailand, Cambodia, South Korea, Japan and Taiwan are also affected and Indonesia admitted it had a problem on Sunday.

Indonesian officials had earlier denied the disease's presence, but the country's veterinarian association said independent investigations had revealed that bird flu had killed millions of chickens over recent months.

The Jakarta Post reported Monday that Indonesian officials may have covered the outbreak there at the behest of politically connected businessmen who feared it would harm their interests. Indonesian officials denied the allegations.

"It's not true. We have zero tolerance for pressure from businessmen. We are talking about the lives of people," Agriculture Department spokesman Hari Priyono said.

The Thai prime minister, Thaksin Shinawatra, faced similar allegations that he covered up his country's outbreak.

Thaksin has said that his government had suspected "a couple of weeks" ago that bird flu had struck his nation but that he didn't tell the public because he feared mass panic.

Thailand has killed some 9 million chickens so far.

The outbreak has devastated Thailand's chicken export industry — the world's fourth largest. Thailand shipped about 500,000 tons of chicken worth $1.3 billion in 2003.

Vietnam has slaughtered more than 3 million chickens.