The National Ports Authority (NPA) has taken steps to ensure the Ebola virus disease does not enter South Africa through one of its main harbours, Public Enterprises Minister Lynne Brown revealed on Thursday.

"As of September 23, all vessels [from certain countries] are required to be stringently screened, by port health officials, at anchor, prior to the vessels entering into any South African commercial port," she said in a written reply to a parliamentary question.

The ports authority is a division of Transnet, and manages all eight of South Africa's main commercial ports -- Richards Bay, Durban, East London, Ngqura, Port Elizabeth, Mossel Bay, Cape Town, and Saldanha.

Brown said the West African states of Guinea, Liberia, and Sierra Leone were rated as high-risk to the Ebola exposure, while Nigeria, Kenya, and Ethiopia were rated medium-risk.

"The mandate for the control of communicable diseases through South Africa's ports lies with the department of health, which has a port health office at each commercial port."

However, the NPA played an important role regarding access and control of vessels entering the harbours they managed.

"The standard practice is for all masters of vessels arriving from ports outside South Africa to declare the state of health for all crew on board their vessels to the port health office."

All vessels from high- and medium-risk countries would be subjected to a search for stowaways prior to being allowed entry to a port.

"As part of the routine port control management procedures, all South African ports... are required to check the last three ports of call for every vessel calling [at] our ports..." she said.