Cluster 7
Cluster 7 : An aggregation of cases of a disease or other health-related condition, particularly cancer and birth defects, which are closely grouped in time and place. The number of cases may or may not exceed the expected number; frequently the expected number is not known. Cases are more likely to represent a cluster if they involve (1) a specific disease or condition, (2) a rare type of disease or condition, or (3) a disease or condition in a group not usually affected by that particular disease or condition, such as a cancer in children that is normally seen in adults