S.P. James, W.D. Nicol and P.G. Shute, ‘Clinical and Parasitological Observations on Induced Malaria,’ Proceedings of the Royal Society of Medicine 29 (1936), pp. 879-894.- External URL
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Date: 1936
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CitesCharles Morley Wenyon
Description:‘The conclusion which seems to emerge from this analysis of the constitution of the primary wave is that its onset and progress were not very different from the onset and progress of epidemics which have occurred under similar conditions in other parts of the world where the bulk of the population at risk possessed little or no natural or acquired immunity to the disease. Among several examples which might be quoted, Dr. Wenyon has reminded me that an epidemic in the town of Nemi near Rome, which we visited together a few years ago, was perhaps as instructive as any. Nemi is one of the so-called " castle towns " in the Alban Hills. It is situated on Lake Nemi, at no great distance from endemic foci of malaria in the Agro Romano but ordinarily, except for imported cases, it is quite free from the disease and anopheles are very rare. In 1928 and 1929 the level of Lake Nemi was lowered about 14 metres in a search for the sunken barges of Caligula. This work created numerous suitable breeding places of anopheles which became very abundant. The result was that in 1929 there was a serious epidemic in which 616 persons out of a population of about 1,000 were affected. This epidemic, like the epidemic in Ceylon, showed that in an area where there are few gametocyte carriers and almost no anopheles, an invasion by great numbers of these insects can give rise. to a serious epidemic provided that the population at risk possesses no immunity to the disease. It is equally true that areas in which there are plenty of anopheles but no gametocyte carriers may almost immediately suffer from an epidemic when a number of gametocyte carrying cases are imported. This is what happened in England and various countries in Europe after the War. In both conditions, for reasons which I mentioned in the discussion on the Ceylon epidemic at a previous meeting of this Society, lack of immunity in the population at risk is almost certainly an essential factor.’ (892)
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QuotesSir Rickard Christophers
Description:‘Discussion. - Sir Rickard Christophers: Of the various points dealt with by the authors of the paper, that relating to the effects of "dose" of infection is one of the most important... From experience of the conditions under which such infections are acquired it is much more probable that the severity of the case has been brought about by massive inoculation of sporozoites. In the laboratory it certainly appears that in bird-malaria infections may be "worked up" by choosing heavy gametocyte carriers for infecting the mosquitoes, just as has been described in human malaria by the authors of the paper at Horton. Recently, in order to obtain uniformity in series of infected birds used in carrying out certain drug tests, it was thought that it might be a good thing for each bird to be bitten by a single mosquito known to have sporozoites in the glands. The plan, however, did not work, owing to the number of negative cases following such a procedure, even though in every case it was certain that the bird had been fed on and that the mosquito feeding had sporozoites. A number of these birds, however, developed infection eventually, say by the tenth or twelfth day instead of on the sixth day. It seemed probable that here minimal dosage had delayed the appearance of infection.
In regard to the causation of epidemics, the final and fully satisfactory answer can onlybe arrived at when the actual conditions have been worked out in the field... [893-894] if we suppose that in normal years time allows only for three geometrically increasing cycles, merely an ordinary fever season results. Increase in the period of optimal conditions (humidity, temperature, &c.), antedating by four weeks the normal, might well, by allowing for a further cycle with its magnified effect, make this an epidemic year.’ (893-894)
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QuotesSir John Megaw
Description:'Discussion. - ...
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Sir John Megaw said that the only question that he wished to ask Colonel James was why he showed such timidity in avoiding the use of the term "virulence? " In connection with parasites of all kinds the word virulence was ordinarily used to express the power of the parasites to damage the hosts, and when Colonel James succeeded in breeding a race of parasites which were capable of causing very serious disease, he (the speaker) saw no reason why their increased capacity for damage should not be referred to as heightened virulence.’ (894)
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Related toHorton Hospital Malaria Therapy Unit
Description:‘It is a matter of common knowledge, which was exemplified during the recent epidemic in Ceylon, that in every malarious country there is a striking clinical-difference between ordinary endemic malaria and the epidemic disease. Why is it that ordinary endemic malaria, whether it is due to the so-called benign species or to the so-called malignant species, is comparatively mild and rarely followed by a fatal issue while epidemic malaria is always serious and is directly responsible for many-deaths? The question is one that is seldom dealt with in textbooks and, when it-is, the severity and fatality are usually attributed to factors other than those relating to the malaria parasite itself and the mosquitoes which transmit it. They are usually attributed to economic stress, hardship, famine, exposure, and other circumstances which sometimes happen to coincide with the epidemic. Reasons of this kind were emphasized by most writers on war-malaria in Eastern Europe and they have been prominently brought to notice in accounts of the recent epidemic in Ceylon. Contrary to this view we think that our work at Horton indicates that a type of malaria closely resembling epidemic malaria can be produced in the absence of any of those adverse circumstances which for this reason must be regarded, in our opinion, as playing only a minor role. We think that the leading role is played by the parasites themselves in the human host and in the mosquito. But in saying that the parasites play the leading role we do not mean that the strains responsible for the endemic disease cause the severe cases met with in an epidemic by becoming more "virulent."... we have no evidence that the inherent virulence of a particular strain can be increased or diminished. The [879-881] change in the parasites which we have observed at Horton (and which we think maybe the change that is responsible for the severity of epidemic malaria) is not an increase of virulence but an increase of physical vigour and vitality, leading to the production of individuals which represent the species in its perfect form... the number of parasites which appear in persons infected with these healthy and vigorous parasites exceeds considerably the number which appear in persons infected with a less active strain. Susceptibility and other factors in the human host being equal, the number of parasites governs the severity of the case, and the result of using a strain which multiplies freely and vigorously is that non-immunes of normal susceptibility who are infected with it develop the severe "epidemic type" of the disease.
At Horton between 1925 and 1930 we succeeded in increasing the physical vigour and activity of an endemic strain of P. vivax from Madagascar to the degree in which it caused this severe "epidemic type" of the disease in 80% of our cases. We did so by using a particular procedure in passaging the strain through the human host and insect vector.’ (879-881)
‘Frequent blood examinations must be made to see that the parasites are not becoming too numerous and there must be careful nursing to keep the temperature within bounds. Where these precautions are not taken the case mortality directly due to the malarial attack may be as high as 10 to 14%.’ (881)
