The World Health Organization has confirmed that three family members who had no known contact with sick or dead poultry but were in close contact with a fourth relative infected with the H5N1 virus likely acquired the infection from each other. While there have been previous reports of familial clusters of human transmission in Vietnam, Cambodia, Thailand, and Indonesia, the Pakistani cases are believed to represent the first documented cases of human-to-human transmission of the virus verified by WHO.
The preliminary risk assessment found no evidence of sustained or community human to human transmission. All identified close contacts including the other members of the affected family and involved health care workers remain asymptomatic and have been removed from close medical observation.
Since 2003, H5N1 has killed 239 of 379 infected people in Asia, the Middle East and Africa.
For additional information, go to http://www.who.int/csr/don/2008_04_03/en/index.html.