Conclusion

In this chapter I have tried to show how epidemiologists, drawing on the unique perspectives of their profession, reacted to the outbreak of a new disease of unknown cause. These scientists constructed explanations for the syndrome with equivocal results. Almost from the beginning of the epidemic, epidemiologists conceptualized HIV infection as a complex social phenomenon, with dimensions that derived from the social relations, behavioral patterns, and experiences of the population at risk. On the one hand, the epidemiologists' approach may have skewed the choice of models and the hypotheses pursued and may have offered some justification for homophobia. On the other, by defining HIV infection as a multifactorial phenomenon, with both behavioral and microbial determinants, epidemiologists offered the possibility of primary prevention, a traditional epidemiological response to infectious and chronic diseases. Epidemiologists, in effect, laid the basis for an effective public health campaign, and, through publications and conferences, helped make AIDS a concern of policymakers and the public.

Primary prevention, including blood screening, health education, and behavior modification, is currently the only effective social response to

the spread of HIV infection. Recent evidence from San Francisco indicates that the rate of HIV infection has begun to decline, possibly because of a reduction in high-risk sexual activities among homosexual males.^[113] Another investigation shows major changes in the sexual behavior of gay males in New York City.^[114] These results—hopeful signs—have not yet been linked to a decrease in HIV-associated mortality. They may presage, however, a parallel between HIV and infectious-disease history.

Historical epidemiology has shown that medical interventions, both chemotherapeutic and prophylactic, have had little impact on the overall decline in infectious-disease mortality in this century. For example, John and Sonja McKinlay found that since 1900 new medical measures have had almost no detectable effect on U.S. disease-specific mortality rates, as such measures usually occurred some decades after significant declines in death rates had already set in.^[115] Thomas McKeown and his colleagues have obtained similar results in a study on the mortality trends of England and Wales. According to McKeown, the observed secular decline was mainly attributable to community factors, particularly better nutrition and hygiene.^[116] It remains to be seen whether HIV-related mortality will also decline as a result of community-directed hygiene (condoms, clean needles, blood screening) before a vaccine or new chemotherapy can be introduced. If it does, the history of HIV infection will offer a powerful vindication of the epidemiologists' multifactorial social definition of disease and of the public health actions that followed from it.