A reporter made a long journey, much of it spent fighting through mud on a motorbike, to reach the epicenter of a viral outbreak in Africa. Last July, I read an article in a medical journal about a puzzling new strain of the mpox virus that had turned up in Kamituga, a scrappy mining town in the eastern Democratic Republic of Congo, more than 1,200 miles from where mpox was known to be endemic. It seemed to be spreading primarily through sexual contact, moving rapidly between people. That behavior hadn’t been seen in mpox before.
Soon the new strain had spread to a half-dozen countries in Africa, leading the World Health Organization to declare a global emergency.
Much of what I was hearing reminded me of the early days of the H.I.V. crisis. A virus jumps from an animal to a human host, circulates for years in small, isolated communities in Central Africa, and eventually, transport systems, migrant workers and sexual networks tip it into a much more widespread problem.