A study of clustering of cases of leukemia, Hodgkin's disease and other lymphomas in Bahrain.

One hundred and twenty five cases of leukemia, Hodgkin's disease, and other lymphomas were compared with 125 matches controls for space, and time and space clustering in the State of Bahrain. These cases and controls were identified from hospital, pathology and death registries over a period of ten years. Thirty-one percent of the cases living in cities had "effective contact' with at least another case compared to 8.7 percent of the city controls, at a distance of "effective contact' equal to or less than 100 meters. no differences were observed as to the number of "effective contacts' between the cases and controls residing in the villages. When the combined data from the villages and urban areas were analyzed using two different methods, no significant clustering could be reported. Although space clustering in the urban areas is attributed to a hypothesized transmissible or exposure factor, the possibility that such clustering is due to some common characteristics of the persons with these conditions has to be considered.