31.   That is when mad cow disease became a palpable fear among Europeans because of its spread in Britain.

32.   The disease also can become airborne.

33.   The disease has become increasingly deadly as drug-resistant varieties have evolved.

34.   The disease has become resistant to other treatments in many countries.

35.   The disease has become a bigger killer than malaria and AIDS combined, but experts complain that attention has shifted instead to more publicized diseases.

36.   The disease also has become a problem in Oregon, Nebraska and North Dakota.

37.   The disease did not become a worldwide menace, he said, until people left the isolated areas of Africa and carried the virus around the globe.

38.   The MDT was developed when the disease became resistant to the traditional drug, Dapsone.