Flu pandemic is a question of 'when' not 'if', say UN and WHO

AnalysisThe United Nations and the World Health Organisation (WHO) disagree over the likely number of deaths from the next flu pandemic. Dr David Nabarro, a UN health official, warned last week a flu pandemic could kill between five million and 150 million people.

In giving such a wide range, Dr Nabarro said he wanted to prepare people for the "worst as well as for the mildest" impact. But the WHO has distanced itself from this estimate, claiming the fatalities from a flu pandemic would be closer to between two and 7.4 million.

Regardless of which is accurate, both organisations agree a flu pandemic is a question of "when" not "if". The last flu pandemic in 1918 and 1919 killed at least 20 million people, far more than had died during the first World War. With this in mind, the bird flu that has swept through poultry and wild birds in southeast Asia since 2003 is causing concern to scientists and epidemiologists who fear a mutation of this virus could be the start of a new pandemic.

Bird flu is the generic name for strains of the flu virus H5N1. This virus has resulted in more than 150 million chickens and ducks either being killed by the flu or slaughtered to contain its spread.

Last week the virulence of the H5NI strain was underlined when Indonesia confirmed two more deaths, bringing its death toll to five people and that of the region to 65. Most worryingly, these deaths are from a relatively small number of infections. About 120 people have confirmed infections with the virus making it exceptionally lethal with 50 per cent mortality. The so-called Spanish flu pandemic of 1918 had a mortality of just 5 per cent.

Bird flu is more lethal than other flu strains because it contains bacteria that allows it to spread beyond the throat and lungs to become a whole-body infection. The virus is transferred through the avian population in the saliva, faeces and nasal secretions of infected birds.

Humans contract the virus through contact with live infected birds and, in particular,through inhaling dust from dried, pulverised droppings from infected birds.

What public health officials fear is the virus will mutate into a form that can move easily between humans.

While European veterinary experts believe the likelihood of a virulent bird flu strain spreading into the EU remains "remote or low", the Dutch and German governments have ordered that free-range poultry be kept indoors.

Europe has experience of bird flu. An outbreak two years ago in the Netherlands resulted in the death of a vet and the slaughter of 30 million domestic birds.

Most EU member states, including the Republic and Britain, have adopted a wait and see approach while increasing surveillance on domestic flocks and migrating birds.

Aside from early detection, the other tactic being used to counter a potential pandemic is stockpiling of anti-virals. These mitigate the effects of a flu outbreak and slow its spread, allowing scientists time to develop a vaccine to counter a specific strain. Developing a vaccine can take six months.

Most countries including the Republic are stockpiling sufficient anti-virals to treat 25 per cent of their population. The Department of Health has ordered one million doses of tamiflu, an order that will not be completed until Easter 2006.

A vaccine for the H5N1 strain is also under development and the department has ordered 200,000 doses of these. However, this vaccine would be ineffective if the virus mutates.