Health workers in Democratic Republic of Congo will begin a vaccination campaign on Monday aimed at containing an outbreak of the deadly Ebola virus, Reuters cited a spokeswoman for the health ministry as saying. Jessica Ilunga said 4,000 doses of vaccine were shipped on Saturday to Mbandaka, which last week registered the first cases in an urban area since the latest flare-up of the disease was announced earlier this month. Cases in Mbandaka, a port city on the Congo river, have raised concerns that the virus could spread downstream to the capital Kinshasa, which has a population of 10 million. The outbreak is Congo's ninth since the disease made its first known appearance near the vast central African country's northern Ebola river in the 1970s. An Ebola epidemic killed more than 11,300 people in West Africa in 2013 to 2016. According to Congolese health ministry data released late on Saturday, there have been four cases of Ebola confirmed through testing in Mbandaka's Wangata neighbourhood and another two suspected cases. One patient has died there, the figures showed. Medical charity Medecins Sans Frontieres has established an isolation ward at a hospital in Wangata, where health personnel could be seen being sprayed with disinfectant before entering the facility on Sunday. The World Health Organization (WHO) said on Friday that Ebola -- which causes hemorrhagic fever, vomiting and diarrhoea and is spread through direct contact with body fluids from an infected person -- had killed 25 people since early April.