The UN health agency on Wednesday said it would carry out an emergency vaccination campaign in six DR Congo provinces to counter an outbreak of measles that has killed 3,600 since the start of the year.
Authorities have registered more than 183,800 suspected cases of the disease, preventable with a vaccine, from the start of the year until September 17, the World Health Organization said.
It said 3,667 people had died in the outbreak, most of them children. That is more than the number who have died in an outbreak of Ebola in eastern parts of the Democratic Republic of Congo.
The campaign aims to vaccinate around 825,000 children in 24 regions, over a period of nine days, the agency said.
"The DR Congo is facing this situation because a lot of children don't get routine vaccinations," WHO representative Deo Nshimirimana said in a statement.
In the country's east, Ebola has claimed more than 2,100 lives since erupting last August.
Measles is a highly-contagious disease caused by a virus that attacks mainly children. The most serious complications include blindness, brain swelling, diarrhoea, and severe respiratory infections.
Last year, cases more than doubled to almost 350,000 from 2017, according to the WHO, amid a rise in "anti-vaxxer" sentiment in some countries that can afford the vaccine, and lagging resources for the preventative measure in poor nations.