The so-called "Lujo" virus infected five people in Zambia and South Africalast fall. Four of them died, but a fifth survived, perhaps helped by amedicine recommended by the scientists.

It's not clear how the first person became infected, but the bug comes froma family of viruses found in rodents, said Dr. Ian Lipkin, a ColumbiaUniversity epidemiologist involved in the discovery.

"This one is really, really aggressive," he said of the virus.

A paper on the virus by Lipkin and his collaborators was published online Thursday on in PLoS Pathogens.

The outbreak started in September, when a female travel agent who lives onthe outskirts of Lusaka, Zambia, became ill with a fever-like illnessthat quickly grew much worse.

She was airlifted to Johannesburg, South Africa, where she died.

A paramedic in Lusaka who treated her also became sick, was transportedto Johannesburg and died. The three others infected were health careworkers in Johannesburg.

Investigators believe the virus spread from person to person through contact with infected body fluids.

"It's not a kind of virus like the flu that can spread widely," said Dr.Anthony Fauci, director of the National Institute of Allergy andInfectious Diseases, which helped fund the research.

The name given to the virus — "Lujo" — stems from Lusaka and Johannesburg, the cities where it was first identified.

Investigators in Africa thought the illness might be Ebola, because some of thepatients had bleeding in the gums and around needle injection sites,said Stuart Nichol, chief of the molecular biology lab in the CDC'sSpecial Pathogens Branch. Other symptoms include include fever, shock,coma and organ failure.

Samples of blood and liver from the victims were sent to the United States,where they were tested at Columbia University in New York and at CDC inAtlanta. Tests determined it belonged to the arenavirus family, andthat it is distantly related to Lassa fever, another disease found inAfrica.

The drug ribavirin, which is given to Lassa victims, was given to the fifth Lujo virus patient — aJohannesburg nurse. It's not clear if the medicine made a difference orif she just had a milder case of the disease, but she fully recovered,Nichol said.

The research is a startling example of how quickly scientists can nowidentify new viruses, Fauci said. Using genetic sequencing techniques,the virus was identified in a matter of a few days — a process thatused to take weeks or longer.

Along with Fauci's institute, the National Heart, Lung, and Blood Institute and Google also helped fund the research.