Mireille Efonge got sick a few months ago, with a fever and painful blisters on her groin. She became too weak to move, so neighbors carried her to a health center with walls of plastic sheeting in Pakadjuma, a crowded, poor community in Kinshasa, the capital of the Democratic Republic of Congo.
There, a nurse called an ambulance to take her to a hospital. Soon lesions broke out on her head and the rest of her body, each one a hard nub of throbbing pain.
Finally she was given a diagnosis: mpox. “I’d never heard of it,” Ms. Efonge said.
This was back in August, when the mpox virus — closely related to smallpox — was still almost unknown in Kinshasa, a city of 17 million people.
Some researchers now recall that time almost wistfully, because it might still have been possible back then to fence in the mpox virus, to fend off disaster.
That window has probably closed, they say.
The detection of a new, fast-spreading strain of the virus in a remote mining town in eastern Congo led the World Health Organization to declare mpox a global public health emergency in August. Since then, its spread has only accelerated.
The virus is taking hold in crowded camps home to millions of displaced Congolese, who live crammed into rough shelters with limited access to water. And it has reached Congo’s cities, including its enormous, congested capital.