Lagos traffic, where sturdy Mercedes play bumper cars with rickety matatas, vans crammed with dozens of passengers and sometimes a few extra on the door. A car horn is just about the only traffic signal. Public health officials worry that if a SARS-like microbe where to hit one of the sprawling cities of the developing world, such as Lagos, the crowded conditions and poor sanitation could quickly ignite an epidemic.

Photo: Laide Shokunbi