The Ebola outbreak in DR Congo has spread from the countryside into a city, prompting fears that the disease will be increasingly hard to control.
Health Minister Oly Ilunga Kalenga confirmed a case in Mbandaka, a city of a million about 130km (80 miles) from where the first cases were confirmed.
The city is a major transportation hub with routes to the capital Kinshasa.
At least 44 people are thought to have been infected with ebola and 23 deaths are being investigated.
Ebola is a serious infectious illness that causes internal bleeding and often proves fatal. It can spread rapidly through contact with small amounts of bodily fluid and its early flu-like symptoms are not always obvious.
The World Health Organization (WHO) has called an emergency meeting of experts to talk about the risk that Ebola might spread beyond DR Congo.
It will meet on Friday to decide whether to declare an international public health emergency which would trigger a larger global response, like in the case of the 2014-16 Western African Ebola outbreak and the 2016 Zika virus in Latin America.