Isles; (2) the absence of pellagra amongst maize-eating populations living in close proximity to or in the very midst of pellagrous areas, as evidenced by the well-known immunity of towns in Italy. To overcome these embarrassing facts, so telling against the maize theory, the comfortable term " pseudo-pellagra" was invented. The disease is pellagra when it fits in with the orthodox theory and when it can be connected in any way with maize; but when this is not possible, the disease becomes a " pseudopellagra " !
After pointing out (Brit. Med. Journ., 1905) how unsatisfactory are the prevailing theories as to the causation of pellagra, Sambon suggests that it probably belongs to the protozoal group of diseases. The skin lesions, the chronic course, the implication of the nervous system, the beneficial effect of arsenical treatment, he claims, support the protozoal hypothesis. The mononuclear increase in the blood of pellagra patients is an additional argument in favour of the suggestion.
Sambon goes farther than this. He has advanced the hypothesis that the hitherto unrecognized protozoal cause of pellagra is insect-borne, and probably by some blood-sucking midge belonging either to the Chironomidæ or to the Simuliidæ. In favour of this hypothesis he adduces not only the analogy of malaria and trypanosomiasis, but the facts that pellagra is a rural and not an urban disease; that it affects principally field -labourers; that it occurs in the neighbourhood of streams or other water bodies. In his reports he describes many circumstances observed in Italy and elsewhere in support of his views perhaps the most telling is that which refers to the islet of Burano, in the vicinity of Venice. Pellagra is common in Burano and on the neighbouring mainland; but whereas on the mainland the principal sufferers are women, in Burano the disease is confined to men. There are no streams in the town-like islet of Burano, and consequently no Simuliidæ. How account, then, for the local pellagra? And how account for the disease being confined to men?
