Authorities have started to screen passengers who come from Ebola-affected countries at Zimbabwe's three main airports in a bid to stop the deadly virus from entering the country, a cabinet minister said Monday.

Minister of Health and Child Care David Parirenyatwa confirmed to Xinhua that people from the affected West African countries will be monitored for Ebola symptoms for 21 days, which is the incubation period of the virus.

Health officials, however, say the passengers are not being quarantined. The monitoring simply involves keeping record of the passengers' contact details and checking on their health status daily over phone.

"When they come, we do not ostracize them but we follow them up in terms of tracing and getting information on where they will be staying. Our target is to monitor them for the incubation period of 21 days and beyond that we will assume that they are well," the minister said.

He could not readily avail the number of people under surveillance, but hastened to point out there had not been any Ebola case in Zimbabwe.

"Even though we have not received a single case of Ebola in the country, we remain concerned because there is always a risk of the disease getting into the country through people coming from the affected region," he said, adding that people would be quarantined in cases where the disease is suspected.

The current Ebola outbreak in West Africa has killed 961 people and affected 1,779 others since the first cases were reported in Guinea in March this year. So far, Guinea, Liberia, Nigeria and Sierra Leone have reported confirmed Ebola cases.

Zimbabwe has not reported a single Ebola confirmed case during the past six major outbreaks in Africa since 1975.

President Robert Mugabe said last week the country was considering withdrawing its troops from Liberia. Zimbabwe had also started training to equip its health personnel with information and skills on how to respond to the outbreak.

Killing up to 90 percent of the infected people, symptoms of the disease include high fever, headache, joint and muscle aches, sore throat, weakness, stomach pain and lack of appetite.

As the diseases gets worse, it causes bleeding inside the body, as well as from the eyes, ears and nose. Some people will vomit or cough up blood, have bloody diarrhoea and get a rash.