The relation of variations in the level of the ground-water to the incidence and seasonal distribution of malarial fevers in India / by Leonard Rogers.

  • Rogers, Leonard, 1868-1962.
Date:
[1898?]
Catalogue details

Licence: Public Domain Mark

Credit: The relation of variations in the level of the ground-water to the incidence and seasonal distribution of malarial fevers in India / by Leonard Rogers. Source: Wellcome Collection.

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    stantly high ground-water, in which the factor of evapora¬ tion plays by far the largest part. There are two other points which I wish to refer to, which are of considerable importance, both from the practical and the theoretical standpoints. They are, firstly, the strictly localised action of the variations in the ground-water level; and, secondly, the light which their discovery throws on the manner in which the infection of malarial fever takes place. Instances of the former have been given both in the case of Doranda, and in that of the variations in the fever rate in the three parallel tea garden lines. In the first instance, there was very little in the conformation of the ground to suggest the great difference in the variations of the ground- water in the areas which were but some 200 yards apart, and the surface levels of which did not differ by more than 3 ft. or 4 ft. Yet in the one spot the water rose to within 5 ft. of the surface, while in the other it remained 25 ft. down. It is well known that sites for camps and canton¬ ments, which have been selected by medical officers as the most suitable, have had to be subsequently abandoned owing to their proving to be very malarious. I would suggest that before choosing between two or more ap¬ parently favourable sites, if a well were first sunk, and the variations of the water-level recorded during the rainy season—or, better, for a whole year—it would be found that the one in which the water-level was lowest and varied least would prove to be the least malarious; and it is pos¬ sible that large sums which have before now been spent in building barracks, which have afterwards had to be abandoned on account of their unhealthiness, might be saved. Again, such measurements may point to deficiency of surface drainage which was not previously apparent, as was the case in the Doranda lines and the tea garden tank, the remedying of which might prevent much fever. Secondly, it is evident from the two instances just referred to, that the infection arose from the very ground-on which the houses of the regiment, and of the coolies respectively, were built. There is no necessity or reason to suppose that the infection was carried by mosquitoes, or any other such medium. The first chart that I have shown can only be explained on the hypothesis that the rise of the ground- water displaces the air from the interstices of the soil, and causes the malarial organisms, which live in the earth, to be carried up into the atmosphere, when they are breathed in by the persons living over the affected ground. The infection probably takes place chiefly during the night, when the powers of resistance will be lowest. In the case of drying-up ground or marsh, again, the infection will be through the air; and I am of the opinion that this mode of infection in malaria is the general one, although it is undoubtedly true that the disease may also be conveyed through water. The fact that all the water in many of the gaols of the Punjaub was for several years boiled without any diminution of the prevalence of malarial fevers, also points very strongly to infection through the air being far more common than that through water, while all the facts already given point in the same direction. Any malarial organisms which may be breathed into the lungs have only a very thin layer of tissue to traverse in order to obtain access to the blood, where they live and multiply. It has recently been strongly urged, especially by Dr. Patrick Manson, that these organisms must in some way escape from the body to pass through an extra-corporeal part of their life-cycle. This is very probable, although in the case of ordinary malarial fevers it is equally possible that the germs, which are so widely distributed, may have a complete existence outside the body, and are, so to speak, only facultatively parasitic. In the case, however, of the epidemic communicable forms of malarial fever (such as I have recently shown the Assam disease, locally known as under the name of Kala-azar, to be), it is quite certain that the plasmodium malarias must in some way escape from the body of one person and gain access to that of another, either directly through the air, or—as I think is more frequently the case— after going through the soil. In this way only can be explained the manner in which a man contracts the fever while living in an infected village, and, after returning to his own uninfected village, while still suffering from the fever, members of his household first get it, and afterwards others in the village are affected. I will not dilate on this point further in this paper, as I shall be reading one on this epidemic malarial fever before the Medico-Chirurgical Society very shortly, but wish to suggest a possible method of infection in malarial fevers,which will explain all the facts that I am acquainted with. It is this: If malarial fever may be contracted by breathing in the malarial organisms, why should they not be also breathed out again when they have completed their work in the body ? They have only to pass back again into the alveoli of the lungs, and they will be able to escape from these organs more easily than they entered, for the cilia of the air passages will assist their exit. This simple theory seems to me to be much more likely than the elaborate mosquito theory, which is largely based on an analogy between such widely different con¬ stituents of the animal scale as the plasmodium malar ice and the Jilaria sanguinis hominis ; while it is also, I think, more in consonance with the known facts as to the in¬ cidence and seasonable distribution of malarial fevers. However this may be, it is rather the more practical points of the very fx-equent dependence of malarial fevei-s on purely local and often removable variations of the ground-water level on which I chiefly wish to lay stress in this papei', and I hope that the evidence I have adduced will afford material for an intex-esting discussion.