james a. crabtree, associate dean of the university of pittsburgh graduate school of public health, dr. dolan j. davis, associate director of research at the national institute of allergy and infectious diseases, united states public health services. dr. george f. lowe, secretary and general manager of the american medical association. "the silent invader" was written by tom colon, produced by roger wolf, directed by jack simon, script research by rose marie scoffyellow, and kay mcdonough. "the silent invader" has been brought to you as a public service by the westinghouse broadcasting company in cooperation with the american medical association, the public health service of the u.s. department of health education and welfare, and the university of pittsburgh health center. announcer: this is american history tv featuring events, interviews, archival films, and visits to college classrooms, museums, and historic places. exploring our nation's past every weekend on c-span3. on "lecturesnight in history," we visit the classroom of professor nicole myers-turner who teaches about enslaved of formerly afri