L. loa and the disease known as Calabar swellings, and, also, between Calabar swellings and mf. diurna. Moreover, as a considerable number of cases of L. loa concurring with mf. diurna have now been recorded by Prout, Henley, Brurnpt, Wurtz, Penel, Kerr, and myself, and as the concurrence of the geographical range of the two forms of parasitic infection has been fairly well made out, there can be little doubt that L.loa and mf. diurna are respectively the mature and larval form of the same species.
Geographical distribution.— We have no definite knowledge of the extent and details of the geographical range of L. loa. It appears to be widely distributed throughout tropical West Africa from Sierra Leone to Benguella. In some parts— as in Old Calabar, Cameroons, and the Ogowé River —a very large proportion of the inhabitants are affected. How far it penetrates into the interior of the continent is as yet unknown. I have seen several cases in Europeans from the Upper Congo within a few miles of Stanley Falls. Brumpt records its presence in Kassai, approximately 600 miles from the coast, on one of the chief tributaries of the Congo. The larval form (mf. loa) has been found twice by Cook in Uganda, although such isolated findings cannot be taken as landmarks, seeing that L. loa is a long-lived parasite and its hosts may have contracted the infection years previously, and at a distance from the place at which it was recognized. At the time of the slave trade numerous cases were reported from the West Indies and South America, but always in negroes from Africa, and their occurrence ceased with the abolition of slavery. The suggestion that about 1795 there existed an endemic centre for this parasite in San Domingo is based on very doubtful evidence. Nowadays, cases are occasionally seen in Europe and America, in both negroes and whites, but only in persons who have frequented those parts of Africa inhabited by the parasite. Possibly, on account of the opening of new trade routes and of the more frequent intercourse between the natives, L. loa may greatly extend its range in Africa.
