By Jason Gale

Dec. 16 (Bloomberg) -- Five members of a family in Pakistan are among eight people who may be the country's first human cases of bird flu, the World Health Organization said. At least one brother died.

Pakistan's national laboratory found the lethal H5N1 avian flu strain caused the infections in three brothers and two cousins from the same family, according to information from a Dec. 15 WHO statement and Gregory Hartl, a WHO spokesman in Geneva. Another brother from the U.S., who attended a funeral for one of the victims, and his son tested negative for the virus at a hospital in Nassau County, New York, Hartl said.

Medical teams have been sent to Pakistan to assist local authorities in investigating the cases, in which two people had only mild symptoms, Hartl said. Doctors are monitoring for signs avian flu may be adapting to humans by killing fewer people, fostering its spread.

"It's too early to make any definitive conclusions'' about the outbreak, Hartl said in a Dec. 15 telephone interview. "We are still in the middle of it.''

New York State health officials were informed Dec. 7 that a man from Nassau County who had returned from Pakistan told his doctor he might have been exposed to avian flu, said Claudia Hutton, director of public affairs for the state department of health in a telephone interview.

Voluntary Quarantine

The man went into voluntary quarantine at home, Hutton said. Then his son began developing flu-like symptoms. Samples from both the man and his son were tested at state laboratories and at the U.S. Centers for Disease Control and Prevention in Atlanta. The CDC sent an airplane to Albany to pick up the samples, Hutton said.

The samples came back negative for H5N1 avian flu earlier this week, and the man and his son are no longer in quarantine, Hutton said.

"The man did a courteous thing by seeing his physician and saying "I might have been exposed,''' Hutton said. "In the end, no one in New York is sick.''

Hutton said she didn't know whether the man or his son received antiviral medications. Drugs such as Roche Holding AG's Tamiflu are believed to fight avian flu.

Hutton said that there were erroneous reports on the Internet that another brother of the H5N1-infected family members in Pakistan has returned to the U.S. and tested positive.

`No Risk'

"That's not true,'' she said. "At this point there's no risk to the public or the individuals.''

CDC officials referred all questions to the New York State health department.

The remaining suspected cases in Pakistan include a man and his niece, and a male who worked on a nearby farm.

Doctors from the WHO in Geneva and Cairo, and from the U.S. Navy Medical Research Unit No. 3 in Cairo will arrive in Pakistan during the next two days to track and stem the disease's spread, and to analyze specimens for any genetic mutations in the virus.

Pakistan has reported 44 H5N1 outbreaks in poultry to the World Organization for Animal Health since early 2006. The most recent occurred on Nov. 27 and Nov. 28 in Punjab and North-West Frontier Province, killing almost 20,000 chickens.

The frequent outbreaks in Pakistan and high density of people meant that it was "not surprising'' that human cases eventually occurred in that country, Hartl said.

Chickens, Quails

It is too early to determine whether the cases were caused by an animal source or through limited person-to-person spread, he said. Some of the infected people also kept chickens and quails and it is unclear what personal protective equipment was used during culling operations, Hartl said.

Pakistan authorities sent Tamiflu to the affected area to treat cases and prevent further infection, Hartl said.

"Pakistan has been doing everything right'' in terms of tracing people at risk of infection and preventing its spread, Hartl said.

The infections probably began late October in an agriculture ministry official involved in culling diseased poultry on a farm at Abbottabad in North-West Frontier Province, which borders Afghanistan, Hartl said.

The man fell ill and was cared for by two of his brothers, who also became unwell. One of the brothers died about a month ago and was buried before specimens could be taken for a diagnosis. The other died on Nov. 29 and was positive for H5N1 in preliminary tests, Hartl said. Antibody screening on the first man, who recovered, found he'd been infected with H5N1.

U.S. Brother

A third brother was hospitalized for H5N1 infection and also recovered. A fourth brother who lives in the U.S. tested negative for H5N1 after returning to Pakistan for his brother's funeral, Hartl said.

Two cousins, at least one of who is a woman, were positive for H5N1, although they developed only mild symptoms, he said. A man and his niece, who were also involved in culling poultry on either the same or a neighboring farm, have tested positive, Hartl said. The eighth case is a male farm-worker from Mansehra, about 20 kilometers (12 miles) from the other cases, he said.

The suspected Pakistan cases occurred in the Peshawar area of the country and were detected following a series of culling operations in response to outbreaks of H5N1 in poultry, according to the WHO statement. Samples from the cases are being sent to a WHO reference laboratory in Cairo for confirmation and further analysis.

Avian flu has infected at least one person a month in Asia and Africa during the past three years.

At least 340 people in 13 countries have contracted the virus since 2003, WHO said Dec. 14. Three of every five cases were fatal and most were caused by contact with infected poultry, such as children playing with them or adults butchering them or plucking feathers, according to the Geneva-based agency. It says millions could die if the virus becomes as contagious as seasonal flu and touches off a global pandemic.

Last Updated: December 15, 2007 21:11 EST

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