Until the lab takes it away from epidemiology.

BACKGROUND

It is proposed that, historically, when the conditions are right for laboratory sciences to contribute to causal knowledge, they take the place of epidemiology as leaders in a given field.

METHODS

Review examples of cholera, pellagra, and Kaposi's sarcoma.

RESULTS

In the cases of cholera, pellagra, and Kaposi's sarcoma, epidemiology ceased to be at the forefront of knowledge acquisition when laboratory sciences identified more proximate causes than those that epidemiologic group comparisons could reveal.

CONCLUSION

These three examples deal with diseases, which, at the individual level, appear to rely predominantly on a single factor. For diseases whose causes still elude specific identification by the laboratory sciences, epidemiology may be uniquely equipped to play a leading role.