“You can imagine the sense of panic,” he said. “A hundred thousand ants and carrion flies are coming off the carcass or climbing up your arms. They get inside your hood and are crawling on your face or biting you.

“After half an hour, you have to get out and pull off the hood, clean up and disinfect. It’s not for the faint of heart.”…

Working under those conditions in tropical heat can be excruciating, as Dr. Karesh explained. Other samplers described fogged goggles and cameras, and sweat running down their arms to form water balloons in the tips of their gloves, reducing their dexterity.

“It can be quite a fiddly thing,” said Dr. Eeva Kuisma, a W.C.S. technical adviser. She recalled being with a team that had to stand up in a dugout canoe trying to keep a test-tube rack balanced as they sampled a dead monkey snagged in an overhanging branch.