31.   It may have its origins in World War II, where unsterile battlefield blood transfusions could have spread the virus.

32.   Magazine editors and television writers, they theorized, were helping to spread the virus.

33.   Mainstream theory holds that central Africans were infected by hunting or eating chimpanzees, then spread the virus as the region became crowded with cities and roads.

34.   Most viruses are spread by aphids and leafhoppers, and both of these insects can travel on the breeze.

35.   Moscow is a city of huge flea markets, and they can draw thousands of shoppers who can quickly spread the virus.

36.   Next summer, they may continue to spread the virus here, perhaps at an accelerated pace.

37.   Nowadays e-mail attachments and even tiny programs built into Web pages are being used to spread viruses.

38.   Once people begin experiencing symptoms, they can spread the virus to others.

39.   Ross promptly followed a course almost perfectly designed to spread the virus to others.

40.   Scientists disagree whether sexual activity spreads the virus, which is also found in body fluids.