The prevention of malaria.

  • Ronald Ross
Date:
1910
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Licence: In copyright

Credit: The prevention of malaria. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

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    says, are dangerous because of the mosquitos bred in them, not because of their effluvia. He stated that several species of mosquito carry yellow fever, but mentioned especially the zancudo bobo with legs striped with white — probably the Stegomyia calopas^ which we now know is really the agent. But he mentions no experiments in support of his opinions, which seem to be only ingenious speculations based upon general thought and observation. In 1881, and subsequently, Charles Finlay of Havana repeated a similar hypothesis, apparently independently of Nott and Beauperthuy [1881]. His views, however, differ in an important particular. While Beauperthuy seemed to think that mosquitos originally obtain the disease-giving poison from the marsh in which they breed (and Varro, Columella, and Lancisi believed the same), Finlay held (regarding yellow fever) that they obtain it from sick people. In other words, he thought that the insects simply convey it from patients to healthy persons. The proboscis of a mosquito which bites a patient becomes contaminated by germs in his blood ; the germs multiply in the proboscis; and then enter the blood of any person whom the mosquito bites next—just as bacteria may be carried on a soiled surgical instrument from one person to another. He thought that an insect which had only just bitten a patient could convey the virus; but that the longer it lived after biting the patient the more the germs would multiply in its proboscis, and the larger the dose given to the healthy person would be. He also considered that the mosquito with striped legs {Stegomyia calopus) is the agent of yellow fever. He records some experiments ; but they must have been very doubtful, since we now know that mosquitos which have bitten a patient must live for no less than twelve days before they can infect a healthy person. Like Beauperthuy, he rightly conjectured the species of mosquito which carries yellow fever, and actually placed them in the hands of the men who ultimately solved the problem. 1 J. Guiteras says not (Lancet 18th June 1910).