A manual of practical hygiene for students, physicians, and health officers / By Charles Harrington.

  • Harrington, Charles, 1856-1908.
Date:
1914
Catalogue details

Licence: Public Domain Mark

Credit: A manual of practical hygiene for students, physicians, and health officers / By Charles Harrington. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    spread. ~Ki the place mentioned, the disease is very prevalent, and mosquitoes of the genus Culex are a serious pest. Graham observed that the disease occurred in persons under observation only when they were bitten by infected mosquitoes, and that, when they were bitten, the disease invariably followed. For example : he applied mosquitoes to a person suiFering from it, and, after they had bitten, carried them in a paper box to a village, high up on a mountain, where there was no case of the disease. There they were allowed to bite two apparently healthy persons, in whom, in four and six days, respectively, typical attacks occurred. In a large number of cases, he made examinations of the blood, and in everj^ instance he found in the red corpuscles an amcfiboid parasite which bore considerable resemblance to the malarial organism, but required a much longer time for its cyclic development and showed no pigment at any stage. The organisms were found at times also in the blood plasma. Flagellated forms were observed also in some cases when the blood had stood for some time. Further observation and study are obviously desirable and necessary. TICKS. Although for some years it bas been known that ticks were con- cerned in the spread of certain diseases in animals, it is only recently that they have been found to play any role in the etiology of disease in man. Especially through the work of Ricketts, it has been demonstrated that spotted fever, or Rocky Mountain fever, is transferred by the tick Dermacentor occidentalis. The question as to the cause of this disease is still in dispute; but, according to Castellani and Chalmers,^ the virus can be acquired and transmitted by the larva, the nymph, and the male and female adults of D. occidentalis, and in a few instances can pass through the eggs into a second generation of ticks. 1 Manual of Tropical Medicine, p. 714.