WHO says Pakistan bird flu cluster no cause for alarm as yet

According to an expert at the World Health Organization, the cluster of suspected bird flu cases in Pakistan may be a combination of infections from poultry with limited person-to-person transmission.

In the cluster, eight people in North West Frontier Province, Pakistan's "poultry belt", have tested positive for the H5N1 bird flu virus since late October; of the confirmed cases one man has died along with his brother who was never tested and is not included in the tally.

Six have recovered and one remains under medical supervision in the cities of Abbotabad and Mansehra.

The WHO says though this is Pakistan's first outbreak of bird flu among people, several outbreaks of H5N1 influenza have occurred among poultry and spread to the country's wild birds earlier this year.

Keiji Fukuda, the coordinator of WHO's global influenza program, says though still unconfirmed, it appears that any human-to-human spread was the result of close contact by family caring for sick loved ones as in previous outbreaks in Thailand and Indonesia.

The cases initially caused alarm as there has always been the very real fear that the H5N1 bird flu virus will ultimately mutate and acquire the ability to pass from person to person causing a pandemic.

Almost all human cases of bird flu to date have been the result of close contact with infected birds.

The WHO however says there is no immediate cause for alarm and they are not raising the level of pandemic alert as the cases do not appear to be the result of just human to human transmission.

It seems a veterinarian, who was at the centre of the outbreaks and a number of other suspect cases were exposed to poultry.

The veterinarian assisted with culling operations, became infected but did recover whereas his two brothers who cared for him also became infected and died.

Fukuda says it is quite possible that there was a mixed scenario where poultry to human infection occurred and then possibly human to human transmission within a family.

While this has not as yet been verified experts say human to human transmission would not be particularly surprising or unprecedented.

The H5N1 strain of bird flu remains a disease of animals, but any mutation enabling the deadly virus to pass between humans could trigger a pandemic which could kill millions of people.

So far the largest known cluster of human bird flu cases worldwide was in May 2006 in Indonesia's North Sumatra province, where as many as seven people in an extended family died.

The WHO has dispatched three experts, led by Hassan El-Bushra from it's Cairo office, to help Pakistan investigate the outbreak.

The WHO has a set of six phases of pandemic alert which gauges the level of threat and the world is currently in phase 3, which indicates a new influenza virus subtype which is causing disease in humans, but is not yet spreading efficiently or sustainable among humans.

In terms of public health implications, the WHO are watching for human to human transmission where casual contact leads to infections and fosters large outbreaks in communities.

The U.S. Naval Medical Research Unit NAMRU-3 laboratory from Cairo is now in Pakistan and will conduct further tests on the samples from the suspected cases.

According to the WHO since 2003 there have been 341 cases among people in 14 countries, and 210 of them were fatal.