‘Outlaw’ organism turns informant

In a critical scene in the film remake of the classic 1960s TV series “The Fugitive,” actor Harrison Ford sheds his coat and replaces it with another. This simple deception allows him to escape detection by the swarm of police officers trailing him. The African trypanosome, a blood parasite that causes African sleeping sickness, is, like Ford’s character in the film, a fugitive that changes its “coat” each time the human immune system is about to nab it. Woven of 10 million copies of a single sugar-coated molecule called a glycoprotein, the trypanosome’s surface changes every few days by virtue of a switch that activates a new gene.