South Africa has stepped up precautions to prevent the spread of the Marburg virus into the country from Angola.
Angola has stepped up efforts to combat the outbreak
Health officials believe the risk of the disease reaching South Africa is a small one, but are taking no chances.
The virus has killed 193 people since the outbreak began in northern Angola, the World Health Organisation says.
"We can't afford to underplay the severity of this disease," health department spokesman Solly Mabotha told the BBC News Website.
"I wouldn't say the concern is great, but obviously we are not taking this lightly."
Public and private hospitals have been warned to look out for patients coming from high-risk areas in Angola and certain of its neighbouring countries.
"We're not saying they shouldn't treat them, but they must be aware and alert us," Mr Mabotha said.
"The lesson from the past has been that private patients have come into the country and put our health workers at risk."
Health workers are training volunteers in Angola
Mr Mabotha said passengers arriving at airports in South Africa from Angola are being asked about their travel history and whether they had been in contact with people recently hospitalised.
"Obviously we don't want to treat each and every Angolan as someone carrying a disease - we have to narrow the list down," Mr Mabotha said.
"So far the process is working, because no cases of Marburg have been reported in South Africa."
The Health Department has also identified hospitals in all nine provinces of South Africa as isolation sites to which people could be taken in the event that they were identified as carrying the virus.
"The best way to manage the disease would be through isolation," Mr Mabotha said.
The Health Department has also advised the South African National Defence Force to screen South African soldiers serving in countries where a risk was present.
Dr Lucille Blumberg of the National Institute for Communicable Diseases in South Africa said the risks of importing Marburg into South Africa are small, but the country needs to be on the alert.
"Although there is a high flow of travel between Luanda and South Africa, local transmission of Marburg has not been reported in the capital . The outbreak is centred in Uige, but cases of Marburg originating there had been treated in various provinces."
Marburg carriers do not start showing symptoms for at least four days - and sometimes as long as three weeks - after contracting the virus, which makes it possible for someone to enter another country without being aware they are carrying the virus.