Whole-Blood Amino Acids in Experimentally Induced Typhoid Fever in Man

A significant increase in whole-blood amino acids was observed during the incubation period of experimentally induced typhoid fever in man. Ten of the 17 subjects became ill. Retrospective analysis of amino acid changes permitted recognition of impending illness in nine of the 10. A significant increase was not observed in any subject in whom clinically apparent disease did not develop. A significant decrease in blood amino acid concentrations was observed to accompany and follow clinical illness in the subjects who were ill. This appeared to correlate more closely with the presence of overt illness rather than mere infection. Blood amino changes may represent one of the earliest detectable metabolic changes after infection. Evidence is rapidly accumulating that evaluation of amino acids may provide a useful tool in the early diagnosis of infection and may yield important clues to the biochemical and physiologic factors involved in the pathogenesis of disease.