Lead image for Why Congo's Ebola outbreak is spreading faster than previous epidemics.
The Ebola epidemic in Democratic Republic of Congo is on track to surpass 4,000 cases this week and has been described as the fastest spreading on record since it was officially declared in May.
It is already the world's second-largest epidemic after West Africa's 2014-16 outbreak in Guinea, Liberia and Sierra Leone, when the World Health Organization recorded more than 28,000 cases and 11,000 deaths.
Delayed detection, overwhelmed surveillance, military conflict and a lack of vaccines and treatments for the species of the virus involved have allowed the disease to outrun containment efforts this time.
How fast is it spreading?
Health officials say the current epidemic is spreading five times faster than previous outbreaks did at this stage.
A 2018-2020 outbreak in Congo was previously the largest on record in the country, ending with 3,481 cases and 2,299 deaths recorded over two years. It took more than 10 months for eastern Congo to surpass 2,000 confirmed cases in that outbreak.
The current epidemic reached that figure in roughly two months and by late July had become the largest Ebola epidemic ever recorded in the country, less than three months after it was officially declared.