Infectious Diseases
Avian flu

The risk of a new human influenza pandemic is considered by the World Health Organisation (WHO) to have increased over the last two years, based largely on the risk posed by the H5N1 avian influenza virus, currently circulating in poultry in South East Asia and elsewhere.

 

History shows that each pandemic is different, and the impact will depend on the characteristics of the virus, such as its clinical attack rate, the severity of the illness it causes, and the resulting case fatality rate. These parameters will not be known until the pandemic virus emerges.

 

Transmission of the pandemic virus from person-to-person will be through close contact. The balance of evidence suggests that the most important transmission routes will be through large droplets (e.g. from coughing and sneezing) and through direct and indirect contact with infected people. Airborne or fine droplet transmission may also occur.

 

Early management of the pandemic will rely mainly on two elements, namely antiviral drugs for treating those who are ill, and robust public health messages encouraging sensible precautionary self-help measures to reduce the risk of an individual becoming infected.

 

 

 

At present there is no vaccine against any future pandemic flu strain. The normal seasonal flu vaccination protects against currently circulating human influenza strains, but is unlikely to offer any protection against avian flu strains or against a new pandemic flu strain. The use of seasonal flu vaccination, by minimising numbers of cases of seasonal flu, would reduce opportunities for avian strains to mix with human strains, and may allow people with avian or pandemic flu to be more easily identified.

 

Anti-viral drugs, such as oseltamivir (Tamiflu ®), may be effective in reducing the severity and duration of an influenza illness, but this has not been proven in a pandemic situation and their effect may be limited if the virus develops resistance to the drugs.