The etiology of malarial fever with special reference to the ground, water level, and the parasite / by Leonard Rogers.

  • Rogers, Leonard, 1868-1962.
Date:
1896
Catalogue details

Licence: Public Domain Mark

Credit: The etiology of malarial fever with special reference to the ground, water level, and the parasite / by Leonard Rogers. Source: Wellcome Collection.

    13/18 (page 54)
    54 [Feb. 1896. and the water-level rose for the fourth time b}^ 1J feet, and at the same time the fever rate rose to a daily average of 1*43. After this there was a more rapid fall of the water-level, interrupted only by a slight rise on October 27th, which apparently was too slight to affect the fever rate; the water-level having by this time reached a depth of 13 feet. The fever curve during this period presents a slow and steady fall, and reached the normal on November 10th, when the water-level was at a depth of 18J feet. These curves appear to me so remarkably parallel as to carry conviction that there must be some etiological relationship between the rise and fall of the water-level and the increase and decrease of the fever curve, and this relationship is strongly supported by another observation which I have made. When engaged daily in examining the accumulating blood specimens from the consecutive cases of fever, I was much struck by the fact that at one time I found the parasite in nearly half the cases examined, while a little later, in as many as ten speci¬ mens running, on which the same time and care was bestowed, negative results were obtained. On subsequently comparing these periods with the water-level chart it became apparent that the parasite was most frequently seen in cases which occurred during a rise in the water-level, and less frequently when it was falling. This observation was found to hold good with regard to each of the four rises and falls of the ground water, During the first rise the organism was found in 5 out of 11 cases examined—that is, in 45 45 per cent ; but during the succeeding fall it was not once found in 4 cases. During the second rise it was found in one out of 5 cases examined, or 20 percent., but not in either of the two ex¬ amined during the following short fall. I do not lay any stress on these figures, as every case which occurred was not examined, except so far as to corroborate those obtained during the two last rises and falls, during which every case was examined, and of which the figures are as follows During the rise to the maximum water-level on August 18th, the organism was found in 57*89 per cent, of the 19 cases which occurred, but during the succeeding long fall, lasting from August 18th to September 15th, it was only found in 20 per cent, of the 35 cases examined. During the fourth rise terminating on September 22nd, it was found in 33 33 per cent, of the cases, and during the following final fall, among the cases which occurred (between September 22nd) up to October 19th, the orga¬ nism was only detected in 17*18 per cent. Again, of all the consecutively examined cases which occurred during the«periods of rising ground water-level, the parasite was found in just 50 per cent., whilst during the periods of a falling ground water it was detected in only 19 56 per cent., or two and a half times less frequently than in the former case. This observation and the parallel nature of the curves of the water-level and fever appear to me to be complimentary to each other, as the same explanation applies with equal force to both. Every one, even the detractors of the mueh-put-upon mosquito, will acknowledge that the malarial organism lives in the ground of infected countries. In addition to the undoubt¬ ed effect of drinking water in causing malarial fever, it is also universally admitted that per¬ haps an even commoner mode of entrance of the organism is through being'inhaled into the lungs and so reaching the blood of the pulmon¬ ary capillaries. When the water rises some feet in the ground, it must displace a correspond¬ ingly large number of cubic feet of air which will pretty certainly carry up with it a certain number of malarial organisms, which will there¬ fore be present in.tho air in a larger number during a period of rising ground water than when it is stationary or falling. If this is so, the effect should be greater the nearer the water is to the surface if the rise of the water-level be fairly equal. This is precisely what is seen in my chart, as the second rise of the fever curve has a greater amplitude than the first, and the third than the second, the water-level having risen towards the surface at a fairly uniform rate dur¬ ing this period. The fourth rise of the water- level is of less amplitude than the first three, and the rise in the fever curve is correspondingly slight. [I may just mention here that a curve of the prevalence of dysentery in Doronda during this rainy season showed three elevations corre¬ sponding with the second, third and fourth rises in the ground water, but in this case the ampli¬ tude of the dysentery variations were in propor¬ tion to the distance of the rise of the water- level, and not in proportion to its nearness to the surface.] [The theory here propounded, that the increase of the fever in Doronda in 1895 was due to the displacement of the air by the rises of the ground water-level, is all the more likely to be correct, because the facts on which it is based were first obtained, and the explanation subsequently thought out,]. There is one more point which tends to confirm both this explana¬ tion and also the views expressed in the earlier part of this paper, that all the cases were of malarial origin. I have worked out the curves which represent the prevalence of the cases in which the organism was found, and also that of those cases in which it was not found in relation to the ground water curve. The curves of the two classes very closely correspond both with each other, and with the ground water curve, but the curve of the parasite cases rises and falls some days before the curve of the non-parasite cases. This fact appears to me to be of great interest and importance, for in the first place it confirms the view that the two classes of cases are of essentially the same nature and caused in the same way ; and secondly, it strongly sup-