Source: Reuters

By Stephanie Nebehay

GENEVA (Reuters) - At least three brothers in Pakistan were infected with the bird flu virus last year, and some human-to-human spread likely occurred, the World Health Organization (WHO) said on Thursday.

But the United Nations agency said the deadly disease had not gone beyond the family cluster near Peshawar, suggesting “limited human to human transmission”.

“This outbreak did not extend into the community and appropriate steps were taken to reduce future risks of human infections,” it said in a statement.

Similar clusters of H5N1 bird flu virus within families have been previously detected in Indonesia, Thailand and Vietnam.

The WHO had earlier confirmed only one human H5N1 infection in Pakistan — a 25-year-old man who died in late November. On Thursday, it said international laboratory tests have now confirmed that two of that man’s brothers also had the disease.

One of those two brothers — who both fully recovered — was a veterinarian involved in culling infected poultry, whose symptoms began in late October, making him the first or “index case” of the bird flu cluster.

None of the veterinarian’s brothers had any direct contact with sick or dead poultry, according to the WHO.

But it said a fourth brother, who also died in mid-November after having close contact with the sick veterinarian, was considered a “probable” case. No blood or tissue samples had been taken from his body, so it never could be proven.

The laboratory test results supported the findings of an investigation of the outbreak that “suggested limited human to human transmission likely occurred among some of the family members which is consistent with some human to human transmission events reported previously,” the WHO said.

The largest known cluster of human bird flu cases occurred in May 2006 in the Karo district of Indonesia’s North Sumatra province, where as many as 7 people in an extended family died.

Experts fear that the virus — which has killed 238 of the 378 people known to have been infected with it since 2003 — could mutate into a form that spreads easily from one person to another. That could trigger a deadly influenza pandemic.

All known close contacts of the Pakistani brothers, including other family members and health care workers, had been monitored and cleared for any signs of infection, according to the WHO.

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Tags: bird flu, H5N1, peshawar, Poultry, World Health Organization