A man arrives at the airport in Lagos, Africa’s most populous city. He collapses. Taken into an isolation ward in a hospital in one of the city’s most crowded areas, he dies. His death is confirmed: he was infected with Ebola. His sister had died of Ebola three weeks previously, back home in Liberia.

Patrick Sawyer, a consultant for the Liberian finance ministry, had boarded a flight in Liberia’s capital, Monrovia. His trip included a lay-over in Togo before it continued to Lagos. Sawyer reportedly began vomiting and had diarrhoea by the time his flight reached its destination. Lagos health officials estimate that Sawyer came into contact with at least 59 people in the course of  his journey.

In Freetown, Sierra Leone’s capital, a 32 year-old woman is forcibly removed from an isolation ward by her family after testing positive for Ebola. A health ministry spokesman describes how her family “stormed the hospital and forcefully removed her and took her away”. Radio stations carry appeals to the public to turn her in for medical attention. “She is a positive case and her being out there is a risk to all,” the radio announcements warned. “We need the public to help us locate her.”

A doctor hailed as a hero for treating more than 100 Ebola patients in Sierra Leone catches the virus he has spent months fighting. Interviewed by Reuters before he became infected, Sheik Umar Khan said: “I am afraid for my life, I must say, because I cherish my life.”

Any one of these scenarios is so poignant and dramatic that you can imagine them as the opening scene to some apocalyptic movie in which a killer virus wreaks havoc on civilization. But this is no movie. All three incidents took place within the last fortnight in West Africa. It’s an Ebola outbreak far more severe and widespread than we’ve seen before.

“This [outbreak] is different from the traditional saga,” Professor Wolfgang Preiser, head of medical virology at the University of Stellenbosch, told the Daily Maverick on Monday.

“Someone goes to the forest, finds a dead monkey, brings it back for meat, and in the process gets contaminated with its blood. He catches Ebola. The family cares for him. They are the next to go. They come to a mission hospital where they have two syringes going around the entire ward, there is a hospital outbreak and the staff becomes infected. Then it dies out because it burns itself out. Survivors flee.”

This time round, things are different. The current outbreak has already spread to three West African countries, beginning in Guinea in December 2013 and subsequently spreading to Liberia and Sierra Leone. South Africa’s National Institute for Communicable Diseases (NCID) reports that the first case affected a 2 year-old child in Guéckédou Prefecture in Guinea, who died on 6 December 2013. From there, it was spread to other areas in Guinea firstly by an infected healthcare worker and secondly by a businessman travelling to the capital, Conakry.

One of the scariest things about Ebola is how little we really know about it, including its origins. Forest animals like fruit bats, chimpanzees and monkeys can play host to the virus, which may then be transmitted to humans via direct contact (such as eating these animals’ meat). Initial symptoms, including fever, can be mistaken for flu or malaria. Then the disease progresses to diarrhoea, vomiting, abdominal pain and bleeding – both internal and external.

There is no known cure or vaccine. But not every case is fatal: over 1200 people are estimated to have been infected so far, with just over 670 dying.

The good news is that Ebola cannot be spread through casual contact, like a common cold. Direct contact with bodily fluids like saliva, sweat and blood, through broken skin or mucuous membranes, is required. The NCID’s Head of Emerging and Zoonotic Diseases, Professor Janusz Paweska, told the Daily Maverick that it is possible that the virus may be transmissible through unprotected sex, but only two instances of this mode of transmission are thought to have been recorded thus far.

Because of the nature of the virus, the two types of people most likely to become infected with Ebola are family members caring for a sick patient, and healthcare workers. Preiser says that due to fear of infection, some healthcare workers have reportedly fled West African hospitals. Others are being barred from doing their job because locals believe it is the healthcare workers themselves who are the harbingers of disease.

The New York Times reported on Sunday that health workers from international organisations like Medecins Sans Frontieres were being blocked from entering some Guinea villages. A 17 year-old told the newspaper: “Wherever those people have passed, the communities are being hit by illness”.

One of the most devastating aspects of the virus is that dead bodies may still be infectious. If family members do not wish to see their loved one cremated, torturous precautions have to be taken during funerals.

“During burial procedures, all involved have to be dressed in special equipment, including gowns, goggles and face shields,” Paweska explained. The bodies have to be bagged in special material and enclosed in special coffins. Unavoidable measures like these will undoubtedly have the effect of further stigmatizing the disease, which may prevent people who fall sick from seeking the help they need.

When the SARS virus spread in 2003, travel restrictions were enforced on major global routes. This hasn’t happened in the case of Ebola yet because the virus can’t be spread by casual contact. But there are still risks. In the case of Patrick Sawyer, the Liberian infected with Ebola who flew to Lagos, passengers could have become infected if they came into contact with traces of vomit or diarrhoea. Preiser suggests, for instance, that if Sawyer had vomited blood all over the airplane toilet and a stewardess had had to clean it up, that exposure would be dangerous.

Lagos health officials are currently trying to trace the passengers and air crew with whom Sawyer is likely to have had contact with. Preiser points out that this is important not just to confirm that they are not infected, but also to relieve them of the trauma of believing that they might be.

The other major risk is that a passenger infected with Ebola would get through airport controls undetected and simply disappear into a major city like Lagos – a metropolis where the population lives so densely that the thought of an Ebola outbreak is highly alarming.

There has never been a case of Ebola acquired on South African soil. But there has been one imported case. In 1996, a sick Gabonese doctor who had been treating Ebola patients in Gabon arrived in Johannesburg to seek treatment. The doctor recovered – but the South African nurse who treated him fell ill and died.

“That is what we are fearing,” says Preiser. “That better-off people [infected with Ebola], those who can afford it, those looking for the best possible care, would fly to South Africa. Doing this, they lose time during which treatment could be started. People will do this, it’s only human; and one is wise to prepare for it.”

South African borders and healthcare facilities are currently on high alert for people who arrive showing signs of fever. But can South Africa’s airport security personnel, for instance, really spot the symptoms of haemorraghic fever in arriving passengers?

“It’s likely to be a flight of several hours. If they were already infectious, by the time they got here they would look…quite sick,” says Preiser. “They would be spottable.” Since April, OR Tambo International Airport has also used infra-red thermal scanners to detect arriving passengers with raised body temperatures.

The problem is that diseases like severe malaria may present themselves similarly to Ebola. “You don’t want to deny someone care who has a serious yet treatable medical condition, but you need to maintain a high level of suspicion,” Preiser says.

If a passenger is suspected of being infected with Ebola, Preiser says they need to be seen by a “very knowledgeable” infectious disease specialist as soon as possible. Blood samples would be sent to the NCID, which is the only place in South Africa which can do testing for the Ebola virus.

Is public fear about Ebola justified? “Yes,” replies Paweska simply. “One reason is the very serious symptoms, and the very high fatality rate.” But he acknowledges that the number of people who have died from Ebola over the past few months is minimal compared to those who have fallen to malaria, HIV/Aids, or TB.

The Ebola death toll thus far is “the grim harvest that TB takes almost every week in South Africa,” Preiser says. Yet he agrees, too, that what makes Ebola especially frightening is the fact that it is “a very brutal disease and it’s very sudden”.

There are other aspects, too, says Dr Rebecca Hodes, a medical historian (and occasional Daily Maverick contributor) who has written extensively on social responses to disease. “Ebola also taps into fears about the lack of public health controls in Africa, and exacerbates these with a panic about the movements of people across borders and countries,” Hodes says. “Africa has long occupied a place in the global imaginary as a hothouse of epidemic disease. Jet travel and 21^st century globalism mean that disease vectors move with remarkable rapidity.”

But for the South African public, there is currently little practical reason to be concerned. Even if Ebola-carriers do enter the country seeking treatment, Preiser says, they will be identified and isolated. In that way, the virus can be contained more efficiently than has been the case in West African countries, where cases have often broken out in rural areas which are poorly resourced.

Overreaction doesn’t help anyone – but Preiser suggests that a state of alertness is currently definitely necessary. “It’s not good to completely downplay it,” he says. “If you are a Joburg airport staff member, or a Joburg hospital worker, you need to have a high index of suspicion.”

Photo: A photograph made available 27 July 2014 shows Liberian health workers in protective gear on the way to bury a woman who died of the Ebola virus from the isolation unit in Foya, Lofa County, Liberia, 02 July 2014.  EPA/AHMED JALLANZO

Read more:

• Ebola outbreak in Africa: the key questions, in the Guardian