In those parts of Africa where the children are plagued by mosquitoes, some die of lymphosarcomas that characteristically arise in their jaw bones or ovaries, the so-called Burkitt's lymphoma. Initially it was believed that the African mosquitoes might serve as vectors of an oncogenic virus, but now it is thought that the plasmodia they carry are the determining, geographic influence. Holoendemic and perhaps hyperendemic malaria, it is postulated, may act as cofactor to an oncogenic virus not itself restricted to Africa, or may act by profoundly modifying the child's response to such a virus or to the lymphoma cell itself.
The first of these current alternatives, that of an additional carcinogenic mechanism, would imply a greater overall incidence of malignant lymphomas wherever Burkitt's lymphomas are common. There is little evidence that this occurs. On the other hand the second theory, that the Burkitt's lymphomas are more frequent where other lymphomas