South Africa on Wednesday reported six new confirmed cases of Covid-19, the respiratory disease caused by the new coronavirus – all involving people who had travelled to Europe.

Thirteen people have now tested positive in South Africa, according to the National Institute for Communicable Diseases.

The new cases are a 33-year-old woman who had been in Italy; a 34-year-old man and a 33-year-old woman who had been in Germany.

Others are a 57-year-old man who had been in Austria and Italy; a 40-year-old man who had been in Portugal; and a 36-year-old man who had been in multiple countries including Germany, Austria, Switzerland and Turkey.

“Some of these patients are already in hospital, while some, specifically those who are asymptomatic, are in self-quarantine,” the institute said in a statement.

Experts consider Africa to be at high risk due to its close links with China – the epicentre of the coronavirus epidemic – and the weak health systems that many African countries have.

But outbreaks have been rather limited on the continent so far.

More than 110,000 people have been infected worldwide so far.

By Tuesday, the World Health Organisation had recorded 99 confirmed Covid-19 cases in nine African countries: Algeria, Cameroon, Egypt, Morocco, Nigeria, Senegal, South Africa, Togo and Tunisia.

Authorities in Burkina Faso and Congo have also announced their first confirmed cases, all involving people who had been in Europe.

Egypt and Algeria have had the highest number of cases. Only one death has been reported so far, in Egypt.