A deadly newly identified virus that causes bleeding like Ebola has killed four of the five people it has infected, researchers say.

The Lujo virus infected five people in Zambia and South Africa last September and October, Dr. Ian Lipkin, an epidemiologist at Columbia University in New York and his colleagues reported Friday in the online journal PLoS Pathogens.

"The course of disease in cases 1 through 4 was fatal; case 5 received ribavirin [antiviral] treatment and recovered," the study's authors wrote.

In comparison, between 50 per cent and 90 per cent of people infected with Ebola virus succumb to death by internal bleeding.

The virus was given the name Lujo after Lusaka, Zambia, and Johannesburg, South Africa, the cities where it originated.

Health workers killed

The first case was a female travel agent who lived outside Lusaka, became ill and quickly grew worse.

She was airlifted to Johannesburg where she died.

A paramedic in Lusaka who treated her also fell ill, as did three other health workers in Johannesburg who were exposed before barrier nursing precautions were taken, the researchers said.

It's not known how the first patient became infected, but Lujo is a member of the arenavirus family of viruses, which most often infect humans when they inhale dust contaminated with rodent waste.

It's thought that the virus then spread through contact with infected body fluids, the researchers said.

Viral family tree

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

The patients had symptoms similar to Ebola, including bleeding gums and bleeding around injection sites, said Stuart Nichol, chief of the molecular biology lab in the CDC's Special Pathogens Branch.

Other symptoms included fever, shock, coma and organ failure.

Test of blood and liver samples at the CDC in Atlanta showed it is an arenavirus, distantly related to Lassa fever, another hemorrhagic illness.

It's not clear if the ribavirin treatment helped the fifth patient, a nurse, to recover, or if she had a milder case, Nichol said.

Lujo has not been officially approved as the name for the new virus.

The study was also funded by the U.S. Heart, Lung, and Blood Institute and Google.org.

With files from The Associated Press