ISLAMABAD (Reuters) - Pakistan is urging provincialauthorities to obey health guidelines to stop any bird fluoutbreaks after fears lapses in poultry culling methods led toeight people being infected with the H5N1 virus.

The Health Ministry is sending out messages via radio andpamphlets to villages and farms in North West FrontierProvince, where the eight people, including a veterinarianinvolved in culling, were infected in South Asia's first humancases.

The vet's brother died of bird flu. A third brother alsodied but it is unclear if he was also infected with the virus.

"These winter months are critical," Federal HealthSecretary Khushnood Akhtar Lashari told Reuters on Thursday.

"We are asking provincial authorities to adhere to safelyguidelines, but it is quite difficult because many of theseplaces are in remote areas and many people have the attitudethat 'it can't happen to me'."

Authorities now believe there is no threat of a pandemicfrom the bird flu cases in Pakistan as World HealthOrganisation experts carried out tests in the region.

But the H5N1 thrives best in winter months in part becausepeople spend more time indoors and in close proximity to eachother and their livestock.

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

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

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

The case highlights the difficulty of health control inPakistan, where the health system is weak, particularly in thecountryside. Many villagers are also illiterate, makingcommunications harder.

In the Pakistan cases, the WHO said they were likely to bea combination of infections from poultry and limitedhuman-to-human transmission of the H5N1 avian flu virus due toclose contact.

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

A WHO report on Pakistan is due in the coming days.

The H5N1 virus is hard for humans to catch and is mainly abird disease. But experts fear the strain could spark a globalpandemic and kill millions if it mutates into a form thatspreads easily between people.

A WHO team, led by Hassan El-Bushra of its regional Cairooffice, have been in Pakistan this week helping investigate theoutbreak.

Since H5N1 resurfaced in Asia in late 2003, the virus haskilled 209 people in 11 countries, according to the WHO. Thelatest Pakistan cases have yet to be included in the formal WHOtally.

(Editing by Robert Birsel)