The medical charity Médecins Sans Frontières/Doctors Without Borders (MSF) says there are now four confirmed cases of Ebola in a city in the Democratic Republic of Congo.
The new case was identified in Mbandaka - a city of nearly 1.2 million people in Equateur Province in the northwest of the country.
Figures from the country's Ministry of Health say there are 17 laboratory-confirmed cases overall.
Four of these are from Mbandaka and 13 are from the Bikoro area.
These cases are part of the 45 people already presenting symptoms, while the number of deaths have risen to 25.
The World Health Organisation (WHO) says the health facilities in Bikoro have "very limited functionality" and the affected areas are difficult to reach, particularly during the current rainy season.
The WHO says it is deploying around 30 experts to conduct surveillance in the city and is working with the Ministry of Health and partners there to engage with communities on prevention and treatment.
#RDC #Equateur Les équipes d'urgence de #MSF déjà sur terrain ont installé une zone d'isolation de 5 lits à l’hôpital principal de #Mbandaka et 10 lits à l’hôpital de #Bikoro. 2 centres de traitement #Ebola de 20 lits chacun sont en construction pic.twitter.com/Gc9Ic96a8Q
— MSF in DRC (@MSFcongo) May 18, 2018
Conditions to declare a PHEIC (Public Health Emergency of International Concern) have not been met.
However, the WHO declared that the Ebola health risk assessment in the country has raised from 'moderate' to 'very high'.
MSF says: "The situation is worrying, and MSF teams in the field are assessing and adapting their response as the context evolves".
MSF teams are currently in the Mbandaka and Bikoro areas, and are putting in place two Ebola treatment centres with 20 beds each.
WHO regional director for Africa, Dr Matshidiso Moeti, says: "The arrival of Ebola in an urban area is very concerning and WHO and partners are working together to rapidly scale up the search for all contacts of the confirmed case in the Mbandaka area."
