Why Ebola is so dangerous
The World Health Organization (WHO) says it is taking "very seriously" the current outbreak of the Ebola virus in West Africa. Out of 122 cases recorded in Guinea so far, at least 80 patients have died, with a further four deaths in Liberia.What is Ebola?
Ebola is a viral illness whose initial symptoms can include a sudden fever, intense weakness, muscle pain and a sore throat, according to the World Health Organization. And that is just the beginning: the next stage is vomiting, diarrhoea and - in some cases - both internal and external bleeding.
The disease infects humans through close contact with infected animals, including chimpanzees, fruit bats and forest antelope.
It then spreads from one person to another: by direct contact with infected blood, bodily fluids or organs, or indirectly through contact with contaminated environments. Even funerals of Ebola victims can be a risk, if mourners have direct contact with the body of the deceased.
The incubation period can last from two days to three weeks, and diagnosis is difficult. The human disease has so far been mostly limited to Africa, although one strain has cropped up in the Philippines.
Health care workers are at risk if they treat patients without taking the right precautions to avoid infection.
People are infectious as long as their blood and secretions contain the virus - in some cases, up to seven weeks after they recover.Where did it strike?
Ebola outbreaks occur primarily in remote villages in Central and West Africa, near tropical rainforests, says the WHO.
The most frequently affected countries are further east: the Democratic Republic of Congo, Uganda and Sudan. This outbreak is unusual because it is centred in Guinea, which has never before been affected and is spreading to urban areas.
This outbreak began in Nzerekore, a remote area of south-eastern Guinea, but has now reached capital Conakry (population: two million). Four people have died in neighbouring Liberia. Sierra Leone has reported five suspected cases, but none has yet been confirmed.
One of the Liberian deaths was of a woman married to a Guinean national. She died in Liberia but caught the disease in Guinea.
The medical charity Medecins Sans Frontieres (MSF) says the outbreak is "unprecedented" in the way the cases are scattered in multiple locations across Guinea, hundreds of kilometres apart.What is being done?
Avoid contact with Ebola patients and their bodily fluids, advises the WHO. Do not touch anything - such as shared towels - which could have become contaminated in a public place.
Carers should wear gloves and protective equipment, such as masks, and wash their hands regularly.
The WHO also warns against consuming raw bushmeat and any contact with infected bats or monkeys and apes. Fruit bats in particular are considered a delicacy in the area of Guinea where the outbreak started.
Liberia's health minister has advised people to stop having sex, in addition to existing advice not to shake hands or kiss.
A BBC reporter in the Liberian capital Monrovia says many supermarket workers are wearing gloves as a precaution.
Senegal has closed its land border with Guinea. The Senegalese singer Youssou Ndour cancelled his concert last week in Conakry, saying it was not a good idea to bring hundreds or thousands of people together in an enclosed area.What can be done if you catch it?
Not much. There are no vaccines, though some are being tested, along with new drug therapies.
Patients frequently become dehydrated: they should drink solutions containing electrolytes or receive intravenous fluids.
MSF says this outbreak comes from the deadliest and most aggressive strain of the virus, which kills more than 90% of patients.
Other strains are less virulent and have a survival rate of up to 75%.
However, it is not known which factors allow people to recover while others succumb.