"We are asking provincial authorities to adhere to safely guidelines, but it is quite difficult because many of these places are in remote areas and many people have the attitude that 'it can't happen to me'."

Authorities now believe there is no threat of a pandemic from the bird flu cases in Pakistan as World Health Organisation (WHO) experts carried out tests in the region.

But the H5N1 thrives best in winter months in part because people spend more time indoors and in close proximity to each other and their livestock.

Lashari said the man believed to have been infected first, a veterinarian who helped operations to cull chickens and who has now recovered, might have not worn a mask because he suffered from asthma.

He might also have taken his culling equipment back home with him. While he recovered, his two brothers died.

Six people have since recovered, while the remaining case is still being treated, the Health Ministry says.

The case highlights the difficulty of health control in Pakistan, where the health system is weak, particularly in the countryside. Many villagers are also illiterate, making communications harder.

TEAM ARRIVES

In the Pakistan cases, the WHO said they were likely to be a combination of infections from poultry and limited human-to-human transmission of the H5N1 avian flu virus due to close contact.

The WHO says a similar case occurred in Indonesia in 2006 among family members believed to have contracted the virus while caring for sick loved ones.

The H5N1 virus is hard for humans to catch and is mainly a bird disease. But experts fear the strain could spark a global pandemic and kill millions if it mutates into a form that spreads easily between people.

A WHO team, led by Hassan El-Bushra of its regional Cairo office, has been in Pakistan this week helping investigate the outbreak.

A team from the U.S. Naval Medical Research Unit NAMRU-3 laboratory in Cairo has also arrived in Pakistan to test samples from the suspected human bird flu cases, the WHO said on Thursday.

"They are setting up their laboratory and starting to work with the samples," WHO spokesman Gregory Hartl said in Geneva.

The team, composed of two experts, will test samples taken from the suspected cases.

The WHO requires additional testing by one of its network of collaborating laboratories, which includes NAMRU.

Since H5N1 resurfaced in Asia in late 2003, the virus has killed 209 people in 11 countries, according to the WHO. The latest Pakistan cases have yet to be included in the formal WHO tally.

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