Inoculation of Malaria by Anopheles,

BY

C. F. FEARNSIDE, CAPTAIN, I.M.S.,

Superintendent, Central Prison, Rajahmundri, Madras Presidency.

        The Central Prison of Rajahmundri is one of the most " malarious " jails in
India, and from the years 1880—1897, 60 per cent. of admissions for malarial
fever in all the larger jails of this Presidency were accounted for by this prison.
In no less than seven years, between the above mentioned dates, the admission-
rate from this cause exceeded 1,000 per mille. The cold weather months
(November to February) are particularly feverish and the reason of this is not
easy to find. Two explanations for the greater prevalence of ague during the
cold weather may be put forward. First, that the majority of the cases are due
to relapses from former attacks, i.e ., that the malarial sporozoon, either as Plehn's
Karyochromatophile granules," or some form of encysted spores, bursts into
activity owing to the lowered vitality of the inhabitants who wear the same cloth-
ing in winter as in summer. Secondly, it may be that the lower temperature of
the atmosphere (70—85° F.) is more suited for the exogenous development of the
malarial parasite in the intermediate host, the anopheles mosquito. The excessive
numbers suffering from malaria in the cold months cannot be explained on the
superiority in numbers of the anopheles species, because this variety of mosquito
is as common in July as at Christmas.

        In November last I dissected 40 free anopheles, which had at some time or
other been feeding on the blood of the prisoners, and I found malarial sporozoites
in one. This of course gives a fairly high percentage: nevertheless I feel con-
vinced that a considerable number of the febrile attacks in the colder months
of the year is the result of a relapse from former infection. A day may yet arrive
when the plasmodist will be able to differentiate between the hæmamœba of the
relapse and that of the fresh inoculation.

        The prevalence of malaria in Rajahmundri and its prison makes the experi-
mental inoculation by anopheles a difficult matter, and this point must be borne
in mind in dealing with the question. In October last Dr. Patrick Manson suc-
cessfully inoculated his son, Mr. Thorbum Manson, and Mr. Warren with malaria

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