Fever, vomiting and severe diarrhoea are among the symptoms of the highly infectious and extremely lethal Ebola virus, which has claimed thousands of lives in a series of outbreaks in Africa since 1976.
On Wednesday the World Health Organization declared the latest Ebola outbreak in the Democratic Republic of Congo an "emergency of international concern". Here are some facts about the virus:
- Super lethal -
The average fatality rate from Ebola is around 50 percent, varying from 25 to 90 percent, the WHO says.
The virus is highly contagious, making it difficult to contain, especially in urban environments.
It is transmitted to people from wild animals and spreads among humans through close contact with the blood, body fluids, secretions or organs of an infected person.
Ebola is believe to reside in bats, which do not themselves fall ill but can pass it on.
Chimpanzees, gorillas, monkeys, forest antelope and porcupines can also become infected, and humans who kill and eat these animals can catch the virus through them.
- Fever, bleeding -
People who are infected do not become contagious until symptoms appear, which is after an incubation period of between two and 21 days.
High fever, weakness, intense muscle and joint pain, headaches and a sore throat are often followed by vomiting and diarrhoea, skin eruptions, kidney and liver failure, internal and external bleeding.
After-effects have often been observed in survivors, including arthritis, problems with vision, eye inflammation and hearing difficulties.
- Treatment and vaccine -
At present there is no licenced drug to prevent or treat Ebola although a range of experimental drugs are in development.
After the DRC's 10th outbreak started in August, health authorities there began issuing the rVSV-Zebov vaccine on a large scale for the first time.
Developed by Merck laboratories, the vaccine is unlicenced but has been shown to be safe and effective, and the WHO has called for its deployment to be expanded.
WHO experts have also recommended introducing another experimental vaccine, the MVA-BN developed by Johnson & Johnson.
To contain the spread of the virus, patients and people who have been in contact with them are routinely isolated.
Medical personnel are meticulously protected with disposable full-body plastic suits, masks, goggles, gloves and disinfecting sprays.
- Named after a river -
The virus was first identified in 1976 by a team that included a young Belgian microbiologist, Peter Piot, who later founded UNAIDS, the United Nations' agency against HIV/AIDS.
They named the virus after a river in the DRC -- then known as Zaire -- that was close to the location of the first known outbreak.
Four of the virus species are known to cause disease in humans -- Zaire, Sudan, Bundibugyo and Tai Forest.
- Worst outbreak: : 11,300 dead -
The world's worst Ebola outbreak started in December 2013 in southern Guinea and spread to neighbouring West African countries Liberia and Sierra Leone.
It claimed the lives of more than 11,300 people from the nearly 29,000 registered cases, according to WHO estimates.
The real figure may have been significantly higher.
More than 99 percent of victims were in Liberia, Guinea and Sierra Leone, although cases appeared all over the world, sparking panic.
The current outbreak in the DRC began on August 1 in North Kivu province, on the border with Uganda, and spread to neighbouring Ituri.
Two cases were recorded in Uganda in June 2019 and in July a first case was recorded in the DR Congo city of Goma.
So far more than 1,600 people have died from the latest outbreak.
SOURCES: AFP, WHO, US Centers for Disease Control and Prevention (CDC), European Centre for Disease Prevention and Control (ECDC).