Mysterious African disease is a new virus

A mysterious hemorrhagic disease that has killed three people in South Africa and forced others into isolation appears to be a never-before-seen strain of a virus known as an arenavirus, an expert said yesterday.

Genetic testing indicates the virus is a new type of arenavirus - a large family of viruses that include the germs that cause Lassa fever and the mouse-borne lymphocytic choriomeningitis virus, said Dr Ian Lipkin of Columbia University in New York.

The virus causes hemorrhagic disease - meaning it can cause internal and external bleeding.

The first victim was a woman from Zambia flown to South Africa for treatment. A paramedic who accompanied her and a nurse from the clinic where she was taken also died.

Samples from the patients were sent to the US Centers for Disease Control and Prevention and to Lipkin's lab in New York, where genetic tests are used to find new microbes.

The standard way to identify viruses is by growing them in a lab dish, but this method misses many viruses and some simply cannot be cultured, Dr Lipkin said.

"We don't know why it is so pathogenic. It is a new virus, not like Lassa," Dr Lipkin told a news conference at a meeting of infectious disease experts.

The virus is not related to certain other viruses that can cause hemorrhagic disease, such as Ebola or dengue.

South African officials say they are monitoring more than 100 people who may have come into contact with the patients.

Dr Lipkin said the common antiviral drug ribavirin appears to help treat the disease.