MALARIA (syn. ague, intermittent [and remittent] fever, marsh fever, jungle fever, hill fever), a disease caused by the presence of special micro-parasites in the blood, conveyed to man by anopheline mosquitoes and characterized by exacerbations at regular intervals, the so-called "ague fit." The ague fit begins with chilliness, increasing until the whole body shivers and the teeth chatter with cold; the face is pale or livid, the fingers dead white, the nails blue. During this stage the cutaneous vessels are constricted and the surface is cold to touch, but rectal tem perature rises. There is a copious flow of clear, watery urine. The second stage is that of dry heat, the skin is burning and flushed. The urine now is scanty and high coloured. The third stage is that of sweating, which is profuse, and may be drenching. The urine is scanty and deposits a thick brick-red sediment of orates on cooling. The three stages together will probably last six to 12 hours and after a period of 24 hours (quotidian), 48 hours (tertian) or 7 2 hours (quartan) from the commencement of the ague fit, according to the type of infecting parasite, the cycle of symptoms will be repeated. Between attacks the patient is generally in fair health except for that general undermining which the repetition of attacks brings about in time.
Malaria had long been recognized as a disease of world-wide incidence and the cause of a higher sickness and death-rate than any other disease. The finding of malarial parasites in the blood cell by Laveran at Constantine in 188o, the demonstration of the life cycles of the quartan and tertian species of parasite by Golgi in 1885, and of the subtertian fever species by Marchia fava and Celli, and the discovery that the disease is transmitted through the agency of mosquitoes first from bird to bird, by Ronald Ross in India 1897-99, and later from man to man, in conjunction with the investigations and teachings of Patrick Manson and other pioneers, were important factors in a great stimulus to the study of tropical diseases, both of men and of animals in general, and the whole of tropical sanitation was powerfully affected.
parasites which pass an asexual stage in man, living and develop ing in the red blood cells, dividing into young forms or fresh broods in two or three days' time and producing some male and female forms (gametocytes), which are drawn with the blood into the stomach of the female mosquito, and there conjugate and complete a sexual cycle. An oocyst forms from the female gamete and in this a swarm of young sporozoites develop and, becoming free in the body cavity, pass to the salivary glands, whence they are injected at the bite of the mosquito and begin again the asexual stage in man. (See PARASITIC DISEASES.) Malaria parasites are of three species : Plasmodium falciparum, P. vivax and P. malariae, the causal organisms of "subtertian," tertian and quartan fevers respectively. Following the teaching of Laveran, a small body of workers believed that there was but one species, a theory of unity, and on the other hand certain in vestigators, because of minute differences between examples of the same species, concluded there were even further species and gave names to them. However, as Prof. Marchoux pointed out in a thorough review of the question at the First International Ma laria Congress held at Rome in Oct. 1924, experimental research tended to support the idea of plurality and existence of the three species above named. This was supported by the difference and practically constant periods of evolution of each, the trans mission of the same species to healthy subjects, the specificity of culture of the parasites of each of the three species in vitro, and by epidemiological studies.
In malaria symptomology nothing of fundamental importance has been discovered in recent years. There has been advance on our knowledge of the cause and treatment of blackwater fever (q.v.) or haemoglobinuria, the serious nature of which has called forth many investigations, especially in the particular and heavily infected regions where it occurs. Some investigators hold that this condition may arise not only in infections with P. falciparum, but occasionally with P. vivax and exceptionally with P. malariae.