3 April 2008

Two additional H5N1 cases were confirmed by serological testing, thus providing final H5N1 infection test results on a previously reported family cluster in Peshawar.

These tests were conducted by the WHO H5 Reference Laboratory in Cairo, Egypt and the WHO Collaborating Centre for Reference and Research on Influenza in Atlanta, USA. The table below summarises the testing results of the confirmed/probable cases in the family cluster.

• 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.

These laboratory test results support the epidemiological findings from the outbreak investigation in December 2007, and the final risk assessment 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. This outbreak did not extend into the community, and appropriate steps were taken to reduce future risks of human infections.