Host and Environment in Disease

Disease is commonly a result of the interaction between genetic factors of the host and extrinsic factors in the environment. This is illustrated by the hemolytic response of glucose-6-phosphate-dehydrogenase-deficient individuals to certain drugs and infections, and the resistance of patients with sicklecell hemoglobin to falciparum malaria. Nevertheless, most studies of disease focus on either host factors or environmental agents but seldom define the relative roles of each. It is likely that advances in our understanding of mechanisms of pathogenesis of disease, and our attempts to control disease, are dependent upon an understanding of this interaction. Such an understanding may reveal why, when infected with the same agent, some people get an acute infection, some have no evidence of disease, and others get chronic disease or are asymptomatic carriers; why lung cancer develops in some cigarette smokers and not in others; why some people have a toxic reaction to a given