At least 47 people have died in a new outbreak of the Ebola virus in the Democratic Republic of Congo till August 16, said the World Health Organization on Friday. The Ministry of Health declared a new outbreak in North Kivu and Ituri provinces in the African country.

The total number of people affected so far is 87, with 60 confirmed cases, including those of healthcare workers. Of the 47 fatalities, 20 died of Ebola, the organisation confirmed. The medical test results of an additional 47 suspected Ebola virus cases are yet to be verified by a laboratory.

“These healthcare workers were likely exposed in clinics, not Ebola treatment centres, many of which may have been infected before the declaration of the outbreak,” the World Health Organisation said. The agency is now working to “increase awareness of Ebola among healthcare and other frontline workers, and to strengthen infection prevention and control measures”. Vaccination has begun in North Kivu province among healthcare workers and residents.

More cases could be identified as a result of earlier infections developing into illness, reported ABC News, quoting WHO spokesperson Tarik Jasarevic. “The worst-case scenario is that we have these security blindspots where the epidemic could take hold that we don’t know about,” he said.

Another official called the situation “unprecedented”. “It will make the response longer and more expensive,” ABC News quoted Michelle Gayer, director of emergency health for the International Rescue Committee, as saying. The committee is working to contain the outbreak.

This is Congo’s 10th outbreak since the disease was identified in the 1970s. More than 11,300 people died in an Ebola outbreak in West Africa between 2013 and 2016, according to WHO. Ebola is a highly infectious and often fatal disease. The illness causes internal bleeding and is easily transmitted through contact with small amounts of bodily fluid. Its flu-like symptoms make it hard to diagnose. The previous outbreak in May had claimed 23 lives.