A factfile on the deadly Ebola virus, against which the World Health Organization said Friday a prototype vaccine could be “up to 100 percent effective”.
– Toll –
The worst-ever Ebola outbreak started in December 2013 in southern Guinea before spreading to two neighbouring west African countries, Liberia and Sierra Leone.
That outbreak killed more than 11,300 people out of nearly 29,000 registered cases, according to WHO estimates.
The real figure might be significantly higher, however.
More than 99 percent of victims were in the three nations — more than 4,800 in Liberia, more than 2,500 dead in Guinea, and more than 3,900 in Sierra Leone.
The WHO declared the epidemic over in January this year, but this was followed by flare-ups in all three countries.
Liberia said it was Ebola-free in June, prompting the WHO to declare the official end of the outbreak.
– Origins –
Ebola was first identified in central Africa in 1976. The tropical virus was named after a river in the Democratic Republic of Congo — then known as Zaire.
Four of the virus species are known to cause disease in humans — Zaire, Sudan, Bundibugyo and Tai Forest.
The West African outbreak was caused by a variant, called Makona, of the Zaire species which has historically been the most deadly in humans.
Before the recent West African outbreak, Ebola had killed about 1,700 people in four decades.
– Transmission –
The virus’ natural reservoir animal is probably the bat, which does not itself fall ill, but can pass the germ on to humans who hunt it for “bushmeat”.
Other dinnertime favourites in parts of Africa — chimpanzees, gorillas, monkeys, forest antelope and porcupines — are also suspected of transmitting Ebola.
Among humans, the virus is passed on by contact with the blood, body fluids, secretions or organs of an infected or recently deceased person. This can include touching a sick or dead person, and likely also sexual intercourse.
Those infected do not become contagious until symptoms appear. They become more and more contagious until just after their death, which poses great risks during funerals.
– Symptoms –
Following an incubation period of between two and 21 days, Ebola develops into a high fever, weakness, intense muscle and joint pain, headaches and a sore throat.
That is often followed by vomiting and diarrhoea, skin eruptions, kidney and liver failure, and internal and external bleeding.
– After-effects –
After effects have often been observed in survivors, including arthritis, problems with vision, eye inflammation and hearing difficulties