Burkitt's and Other Non-Hodgkin's Lymphomas in Adults Exposed to a Visitor from Africa

DISEASE clustering, the occurrence of cases that are close together in time and space, is often believed to suggest an infectious cause.¹,² Despite numerous anecdotal reports of cancer clusters, Burkitt's lymphoma is the only human cancer for which there is clear-cut statistical evidence of time—space clustering.^{2 3 4} In general, reports of cancer clusters are uninformative, since most cancers have long, variable, or unknown latency periods between etiologic exposure and manifestation of the disease.²,⁴,⁵ A typical reported cluster is characterized by proximity in the time of diagnosis and in the residence of patients at diagnosis. However, the etiologic exposure may have occurred.