The rigor scared Stephen Hoffman. He had felt irritable and feverish all morning in his hotel room. Then, in the midst of a presentation at a meeting of the American Society for Clinical Investigation, he began to shake uncontrollably. Ironically, the subject of that presentation was whether the antibodies elicited by the vaccine he had helped develop would prevent malaria. To prove it would work, he and six of his coworkers took the vaccine and then exposed themselves to the bites of malaria-infected mosquitoes. Five people contracted the disease.
Hoffman immediately went to the University Hospital in San Diego, but the parasite could not be found in his blood. He suffered for 36 hours until a parasitologist finally spotted Plasmodium falciparum parasites in his blood, and Hoffman took the chloroquine that ended the chills and fever.
Since then, Hoffman has gone on to develop a more effective vaccine based on...