Pandemic fears as death toll goes up; BIRD FLU IN SCOTLAND HUMAN RISK.

MORE than 100 people have died from H5N1 bird flu - out of 191 confirmed cases of the strain worldwide.

The latest death toll for the disease is 108, according to the World Health Organisation.

All the people stricken by the virus, mainly in Asia, have worked or lived in close contact with poultry.

Flu viruses are norm ally only specific to one species, be that animals or humans.

But already four types of the virus in birds are known to have caused infections in humans.

The H7N3, H7N7 and H9N2 normally lead only to mild symptoms in humans.

But H5N1 strain leads to serious illness and death.

And experts fear it has the potential to cause a pandemic.

There are two main ways this could happen.

The first is by a process called reassortment - when genetic material is exchanged between human and avian viruses during co-infection of a human.

In this, the human could act as a mixing pot, with the human flu mixing with the avian flu and creating a fully transmissible pandemic virus.

The second would involve a gradual process of mutation, with the virus adapting so it was more successful in infecting humans.

This would usually emerge in a small cluster of cases among humans, which could give the rest of the world some time to take action as long as it was detected early enough.

A vaccine against the disease can not be created until the exact pandemic strain is identified.

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