Animals can warn against Ebola

2004-01-20 13:34

Paris - Central African countries could get an early warning of Ebola outbreaks by monitoring populations of apes and other animals that are vulnerable to the disease, according to a study published on Friday.

The research, which appears in the US weekly journal Science, says outbreaks of Ebola in Gabon and Republic of Congo all followed a dramatic plunge in nearby populations of chimpanzees, gorillas and antelopes.

"Surveillance of animal mortality may help to predict and prevent human Ebola outbreaks," its authors contend.

In the past two years, five outbreaks of the Zaire subtype of human Ebola have occurred in western central Africa, infecting 313 people, 264 of whom died.

The researchers discovered that outbreaks which occurred in Gabon in 2001 were preceded by a high number of dead animals found in the forest near local villages - the bodies of 36 gorillas, as well as several dozen chimpanzees and duikers, a small species of antelope, were found in the space of eight months.

"Hundreds or even thousands" of animals may have died, for anecdotal evidence suggests local populations of these species fell by half, they believe.

Samples taken from the animal carcasses tested positive for the Ebola virus.

Although the natural reservoir for Ebola is unknown, it is likely that humans scavenging for meat picked up the agent by contact with the dead apes and then infected their families and others, the study says.

"Almost all human Ebola outbreaks in Gabon and Republic of Congo have been linked to the handling of dead animals by villagers or hunters, and increased animal mortality always preceded the first human cases," it says.

Lead author of the study is Eric Leroy of the International Medical Research Centre in Franceville, Gabon.

Ebola, one of the world's most feared and contagious diseases, causes raging fever and massive haemorrhaging. Death follows within a few days.

The first known cases occurred in 1976 in what was then Zaire, now the Democratic Republic of Congo, DRC. There have been 10 other known outbreaks since then in sub-Saharan countries, including Ivory Coast, DRC, Uganda, Republic of Congo and Gabon.

There are four subtypes of Ebola, the deadliest of which is the Zaire, which causes up to 88% mortality.

"Given the very rapid spread of the disease and the lack of a vaccine or effective therapy, the cornerstone of management remains the prevention and rapid control of outbreaks," Leroy's study notes.

- SAPA