31.   The disease can occur sporadically, with no explanation, and it can be inherited.

32.   The diseases occur because the communities arose from a small population of founders, and members, who are forbidden to marry outside their religion, marry each other.

33.   This would explain why some autoimmune diseases occur years after that first flu-like infection and why some seem to wax and wane in severity.

34.   Walker said he thinks the disease could occur anywhere ticks live.

35.   When disease occurs and they can perform a transplant, how do they develop regimens to prevent organ rejection?

36.   When the disease does occur in these people, its onset is generally later in life than in less educated populations.

37.   A big question is whether the disease occurs in squirrels, the researchers said.

38.   A big unanswered question is whether the disease occurs in squirrels, the researchers said.

39.   Hand-foot-and-mouth disease most commonly occurs in summer and early autumn.