In May, 1960, two workers in the malarial research program of the National Institute of Allergy and Infectious Diseases became ill with a Plasmodium vivax type of malaria. Investigation showed that the illness had resulted from the bite of mosquitoes infected by a monkey-malaria parasite, Plasmodium cynomolgi, B strain. Soon after, several other accidental infections caused by the same agent occurred in laboratory workers elsewhere. This exchange of malaria between man and monkey suggested that monkeys might be reservoirs of infection, which would present an obstacle to eradication of the disease. This problem is the subject of field studies in Malaya.
After the recognition of human infection by the simian parasites and after trials with volunteers in the Federal Prison in Atlanta, clinical studies were made using human volunteers at the Clinical Center, National Institutes of Health (NIH) in Bethesda, Md. As is so often the case in research, unanticipated