Handbook of medical entomology . Pellagrous eruption on the Watson. Pellagra 247 article of diet, and that its spread was not pari passu with that of theuse of com. Cases were found in which the patients had apparentlynever used com, though that is obviously difficult to establish. Heshowed that preventive measures based on the theory had been afailure. Finally, he believed that the recurrence of symptoms ofthe disease for successive springs, in patients who abstained absolutelyfrom the use of corn, militated against the theory. On the other hand, Sambon believed that the periodicit
Handbook of medical entomology . Pellagrous eruption on the Watson. Pellagra 247 article of diet, and that its spread was not pari passu with that of theuse of com. Cases were found in which the patients had apparentlynever used com, though that is obviously difficult to establish. Heshowed that preventive measures based on the theory had been afailure. Finally, he believed that the recurrence of symptoms ofthe disease for successive springs, in patients who abstained absolutelyfrom the use of corn, militated against the theory. On the other hand, Sambon believed that the periodicity of thesymptoms, peculiarities of distribution and seasonal incidence, andanalogies of the symptoms to those of other i^arasitic diseases indi-. 145. Pellagrous eruption on the hand. After Watson. cated that pellagra was of protozoal origin, and that it was insect-borne. The insect carriers, he believed to be one or more species ofSimuliidse, or black-flies. In support of this he stated that SimuUumappears to effect the same topographical conditions as pellagra,that in its imago stage it seems to present the same seasonal incidence,that it has a wide geographical distribution which seems to coverthat of pellagra, and that species of the genus are known to causesevere epizootics. Concluding from his studies in Italy, that pel-lagra was limited almost wholh to agricultural laborers, he pointedout that the Simulium flies are found only in rural districts, and as arule do not enter towns, villages, or houses. When Sambons detailed report was published in 1910, his theorywas seized upon e^•er>whcre by workers who were anxious to test it Arthropod Transmission of Disease
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