Bacillus Icteroides.—In 1897, Sanarelli isolated an organism which he named Bacillus icteroides. In investigating this organism Reed and Carroll found that it was closely related to the hog cholera bacillus. Certain American investigators substantiated the claims of Sanarelli. Sternberg, however, doubted these findings.
To further investigate the relation of B. icteroides to yellow fever Army surgeons were sent to Cuba in 1900.
American Commission.—In addition to Reed and Carroll, Lazear and Agramonte were also members of the Commission.
The Commission first cultured the blood of 18 yellow fever patients with negative results for B. icteroides in every case.
B. icteroides grows as readily on culture media as does the typhoid organism.
It was also shown that yellow fever blood, which was negative for B. icteroides, could produce yellow fever when injected subcutaneously. In 11 autopsies made shortly after death cultures from various viscera were negative for B. icteroides. It was then decided to abandon, as fruitless, further investigations as to Sanarelli’s organism, and to take up the mosquito transmission theory.
Mosquito Transmission.—In 1848, Doctor Nott, of Mobile, strongly advocated the insect transmission of yellow fever but not specifically incriminating the mosquito.
Riley from a study of Nott’s original paper, thinks that the author had in mind invisible forms of insect life, which could act as disease producers, and simply cited the mosquito to illustrate his views. In 1853, Dr. Beauperthuis, in Guadeloupe, noted that malaria and yellow fever ceased to exist in regions which from their altitude fail to nourish “insectes tipulaires.”
He also thought that the virus of these diseases was introduced by the channel of insect inoculation. Furthermore he stated that the variety, zancudo bobo (Stegomyia), had white stripes on the legs and was in a way the domestic species. However, there is a question whether his zancudo bobo was Stegomyia and furthermore if we translate the expression inoffensif as without result it would negate the connection between this mosquito and disease production.
From 1881 Doctor Carlos Finlay had been advocating the transmission of yellow fever by Culex fasciatus (Synonym for Stegomyia calopus).