Page:Popular Science Monthly Volume 58.djvu/377

Rh that the 'night air,' per se, is no more dangerous than the day air, but that the real danger consists in the presence of infected mosquitoes of a species which seeks its food at night. As pointed out by King, in his paper already referred to, it has repeatedly been claimed by travelers in malarious regions that sleeping under a mosquito bar is an effectual method of prophylaxis against intermittent fevers.

That malarial fevers may be transmitted by mosquitoes of the genus Anopheles was first demonstrated by the Italian physician Bignami, whose experiments were made in the Santo Spirito Hospital in Home. The subjects of the experiment, with their full consent, were placed in a suitable room and exposed to the bites of mosquitoes brought from Maccarese, 'a, marshy place with an evil but deserved reputation for the intensity of its fevers.' It has been objected to these experiments that they were made in Rome, at a season of the year when malarial fevers prevail to a greater or less extent in that city, but Marchiafava and Bignami say:

"It is well known to all physicians here that, although there are some centers of malaria in certain portions of the suburbs, the city proper is entirely free from malaria, as long experience has demonstrated, and at no season of the year does one acquire the disease in Rome."

In view of the objection made, a crucial experiment has recently been made in the city of London. The result is reported by Manson, as follows:

"Mosquitoes infected with the parasite of benign tertian malarial fever were sent from Rome to England, and were allowed to feed upon the blood of a perfectly healthy individual (Dr. Manson's son, who had never had malarial disease). Forty mosquitoes, in all, were allowed to bite him between August 29 and September 12. On September 14 he had a rise of temperature, with headache and slight chilliness, but no organisms were found in his blood. A febrile paroxysm occurred daily thereafter, but the parasites did not appear in the blood until September 17, when large numbers of typical tertian parasites were found. They soon disappeared under the influence of quinine."

We have still to consider the question of the transmission of malarial fevers by the ingestion of water from malarious localities. Numerous medical authors have recorded facts which they deemed convincing as showing that malarial fevers may be contracted in this way. I have long been of the opinion that while the observed facts may, for the most part, be authentic, the inference is based upon a mistake in diagnosis. That, in truth, the fevers which can justly be ascribed to the ingestion of a contaminated water supply are not true malarial fevers—i. e., they are not due to the presence of the malarial parasite in the blood. This view was sustained by me in my work on 'Malaria and Malarial Diseases,'