Why Ebola is so dangerous

The Ebola outbreak in West Africa is the world’s deadliest to date and the World Health Organization has declared an international health emergency as more than 3,850 people have died of the virus in Guinea, Liberia, Sierra Leone and Nigeria this year.

What is Ebola?

Ebola is a viral illness of which the initial symptoms can include a sudden fever, intense weakness, muscle pain and a sore throat, according to the World Health Organization (WHO). And that is just the beginning: subsequent stages are 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 between humans 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.

Healthcare 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.

Ebola outbreaks occur primarily in remote villages in Central and West Africa, near tropical rainforests, says the WHO.

Image caption Bushmeat – from animals such as bats, antelopes, porcupines and monkeys – is a prized delicacy in much of West Africa but can also be a source of Ebola

It was first discovered in the Democratic Republic of Congo in 1976 since when it has mostly affected countries further east, such as Uganda and Sudan.

Ebola deaths since 1976

This year’s outbreak is unusual because it started in Guinea, which has never before been affected, and it quickly spread to urban areas.

Image caption Figures accurate from 4-6 October, depending on country. Death toll in Liberia includes probable, suspect and confirmed cases, while in Sierra Leone and Guinea only confirmed cases are shown

From Nzerekore, a remote area of south-eastern Guinea, the virus spread to the capital, Conakry, and neighbouring Liberia and Sierra Leone.

There have been 20 cases of Ebola being imported by someone travelling from a country of widespread transmission to Nigeria, with eight confirmed deaths. The US and Senegal have both confirmed one case each. The US Centers for Disease Control and Prevention (CDC) said in September that the virus might have been successfully contained in Nigeria and Senegal.

In October, a nurse in Spain became the first person to contract the deadly virus outside of West Africa, after treating two Spanish missionaries who had eventually died of Ebola in Madrid.

Ebola deaths

The medical charity Medecins Sans Frontieres (MSF) says the outbreak is “unprecedented” in the way the cases were scattered in multiple locations across Guinea, hundreds of kilometres apart, and says it is a “race against time” to check people who come into contact with sick people in neighbouring Sierra Leone.

Can cultural practices spread Ebola?

Ebola is spread through close physical contact with infected people. This is a problem for many in the West African countries currently affected by the outbreak, as practices around religion and death involve close physical contact.

Hugging is a normal part of religious worship in Liberia and Sierra Leone, and across the region the ritual preparation of bodies for burial involves washing, touching and kissing. Those with the highest status in society are often charged with washing and preparing the body. For a woman this can include braiding the hair, and for a man shaving the head.

Image caption Strict precautions must be observed when burying those who have died of Ebola

If a person has died from Ebola, their body will have a very high viral load. Bleeding is a usual symptom of the disease prior to death. Those who handle the body and come into contact with the blood or other body fluids are at greatest risk of catching the disease.

MSF has been trying to make people aware of how their treatment of dead relatives might pose a risk to themselves. It is a very difficult message to get across.

All previous outbreaks were much smaller and occurred in places where Ebola was already known – in Uganda and the DR Congo for example. In those places the education message about avoiding contact has had years to enter the collective consciousness. In West Africa, there simply has not been the time for the necessary cultural shift.

Avoid contact with Ebola patients and their bodily fluids, the WHO advises. Do not touch anything – such as shared towels – which could have become contaminated in a public place.

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.

In March, Liberia’s health minister advised people to stop having sex, in addition to existing advice not to shake hands or kiss. The WHO says men can still transmit the virus through their semen for up to seven weeks after recovering from Ebola.

Fighting the fear and stigmatisation surrounding Ebola is one of the greatest challenges health workers face.

But health workers themselves are becoming scared of treating patients, and are demanding better protective clothing when exposed to patients.

Ebola has already claimed the lives of dozens of doctors and nurses in the Ebola-hit region, including Sierra Leone’s only virologist and Ebola expert, Sheik Umar Khan.

This has put a further strain on the health services of these West African states, which have long faced a shortage of doctors and hospitals.

You must keep yourself isolated and seek professional help. Patients have a better chance of survival if they receive early treatment.

Image caption The current outbreak is killing between 50% and 60% of people infected

There are no vaccines, though some are being tested, along with new drug therapies. The WHO ruled in August that untested drugs can be used to treat patients in light of the scale of the current outbreak.

The experimental drug ZMapp has been used to treat several people who contracted Ebola: Two US aid workers and a Briton have recovered after taking it but a Liberian doctor and a Spanish priest have died.

But the US pharmaceutical company that makes it says it has for now run out of it.

Patients with Ebola frequently become dehydrated so 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.

The current outbreak is killing between 50% and 60% of people infected.

It is not known which factors allow some people to recover while most succumb.

Guineans are expected to celebrate the landmark with concerts and fireworks.

The disease killed more than 2,500 people in the country and a further 9,000 in Sierra Leone and Liberia.

Sierra Leone was declared free of Ebola in November, but new cases have emerged in Liberia, which had been declared Ebola-free in September.

A country is considered free of human-to-human transmission once two 21-day incubation periods have passed since the last known case tested negative for a second time.

The disease has had an enormous social and economic impact on Guinea, the BBC’s Ibrahima Diane in Conakry says.

According to the UN, 6,220 Guinean children have lost one or both parents to Ebola.

More than 100 health workers also lost their lives in the fight against the disease.

Meanwhile, survivors are still living in fear of the stigma and long-term side effects associated with the virus, our correspondent adds.

The fight against Ebola was particularly difficult in Guinea, he says.

Some communities initially did not believe there was an epidemic, while others blamed it on Western countries and the Guinean authorities.

The government has blamed the virus for poor economic performance and says it has also caused people to distrust the country’s health services.

President Alpha Conde has doubled the health budget since winning re-election in November.