The risk to humans is small, but we need to be better prepared

An outbreak of avian influenza is ravaging the poultry industry in South East Asia. This carries a devastating economic toll for the communities affected, but what of the associated risk to human health? At least seven people in Vietnam have been infected by the strain of H5N1 subtype influenza found in poultry. Of these six are dead. In Thailand three boys contracted the virus; two are dead. These numbers are small, and investigations and case studies so far suggest that the virus does not transmit from human to human but is acquired directly from close contact with infected chickens. How likely is it that these events signify the emergence of a new human pandemic, and what measures do we have to deal with the global threat?

Although we think of influenza as a human disease, the natural reservoir for influenza A viruses is aquatic birds and wildfowl. Many different strains circulate at any one time, and most are not associated with disease in wild birds. Influenza strains …