50 years ago, scientists were trying to get a grip on Lassa fever

Excerpt from the March 21, 1970 issue of Science News

Multimammate rats

Multimammate rats (Mastomys natalensis), endemic to West Africa, spread Lassa fever to people.

Joe Blossom/Alamy Stock Photo

Studying a killer, Science News, March 21, 1970 – 

In January 1969 an unknown virus was isolated for the first time from the sera of two nurses, who died.… The infection, being called Lassa fever, involved almost all the body’s organs.… Doctors so far suspect that the disease was transmitted by an animal, but what animal is not known. It is also believed that the patients can acquire the infection from one another, but only through more than casual contact.


Named for the Nigerian village where cases first appeared, the Lassa virus causes hemorrhagic fever and kills about 5,000 of the hundreds of thousands of people infected each year in West Africa. The virus, spread by the Natal multimammate rat (Mastomys natalensis), can be transmitted through human body fluids.

The World Health Organization considers the creation of a vaccine a high priority. Of nearly 30 vaccines in development, only one has been tested in people. One clinical trial of that vaccine’s safety and efficacy began in the United States in May 2019, and another trial is set for Liberia, Nigeria and Ghana this month. 

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