December 28, 191 ij 



NATURE 



285 



tific medical work has been done in India, and the 

 number of Paludism referred to adds to it. Major 

 \V. H. Kenrick, special malaria officer, Central 

 Provinces, studies the effect of malaria on birth-rates 

 and death-rates — a difficult subject, which has been 

 considerably neglected,' though it lies at the basis of 

 prevention. He compares thirty-four healthy villages 

 possessing a spleen-rate of only 4 per cent, and a total 

 population of 19,064, with thirty-three " hyperendemic " 

 villages with a spleen-rate of 80 per cent, and a total 

 population of 10,825. The birth-rate in Britain is, I 

 understand, not much affected by season ; but in 

 healthy Indian villages it seems, curiously enough, to 

 be highest in October and November, which the author 

 attributes to increased frequency of conception after 

 the gathering of harvest in the first months of the 

 year. In malarious areas, however, these are also 

 the most feverish months, owing to the accumulated 

 effect of the untreated autumn infections, and the 

 result is that the most favourable conception period is 

 delayed until June-July and the corresponding maxi- 

 mum birth-rate until March-May. Yet the total birth- 

 rate is not much influenced, even by severe endemic 

 malaria, though it is much reduced by epidemic, 

 that is, exceptional malaria. 



The reason for this probably lies in a consideration 

 discussed in section 31 of my book on the prevention 

 of malaria. In regions of high static (i.e. constant) 

 malaria-frequency, nearly all the children are rendered 

 comparatively immune at puberty, so that there should 

 be comparatively little sickness among the adults — 

 enough only, perhaps, to delay conception among the 

 women without stopping it entirely. But in epidemic 

 times the frequency of reinfections is sure to be so 

 enormous (see below) that the comparative immunity 

 will be overcome, and the sickness will suffice to reduce 

 as well as to retard the birth-rate. 



It would be interesting to ascertain by such good 

 studies as those of Major Kenrick how far malaria 

 checks delivery as well as conception. Regarding the 

 death-rate, he finds that during the three years 1908, 

 1909, 1910, they were respectively 24, 22, 23, in the 

 thirty-four healthy villages, and 38, 32, 44 in the thirty- 

 three hyperendemic ones (plague and cholera being 

 absent in all), and concludes that malaria-frequency of 

 over 80 per cent, spleen-rate measure causes an in- 

 crease of from 10 to 15 per mille of total death-rate. 

 Nothing shows better the enormous anti-human effect 

 (as it may be called) of malaria in the tropics ; the 

 single disease, benign as it is, may cause a death-rate 

 nearly equal to the whole death-rate of London due 

 to all causes together. 



Colonel J. R. Adie, special malaria officer, Punjab, 

 found Plasmodia in 38 out of 150 British soldiers at 

 Delhi Fort in November, 1910, and in 29 out of 71 

 children there. Yet all these were undergoing "pro- 

 phylactic quinine treatment " at the time. This con- 

 firms what Malcolm Watson and others have observed 

 elsewhere. In fact, I am beginning to believe that 

 quinine is of little use in regions of very high malaria- 

 frequency, for reasons to be given presently. It is 

 surprising that the military authorities have not tried 

 a more radical preventive measure at Delhi Fort long 

 before this, in preference to allowing such an expen- 

 sive article as a British soldier to be rotted by malaria 

 in this manner. Colonel Adie also gives a good 

 example of the errors of inadequate sampling. The 

 i.;o soldiers were examined in five successive batches 

 of thirtv each, and the percentages found infected were 

 respectively 10, 36, 36, 20. 23, the mean being 25 per 

 cent. Yet important conclusions, quite disregarding 

 such error, have been previously based in India on 

 even smaller samples. 



The simplest, though not quite exact, method of 



NO. 2200, VOL. 88] 



measurmg malaria-frequency is by observing the fre- 

 quency of enlarged spleen (spleen-rate). But as it is 

 easy to estimate roughly at the same time the degree of 

 the enlargement, I have advocated for several years 

 the additional computation of the average size of 

 spleen and average degree of enlargement found. 

 Thus in Mauritius in 1907-8, in 30,137 children 

 examined by a number of workers at my suggestion^ 

 we estimated that the average size of the spleen was 

 2-54 times the normal, the whole number of children 

 aftected being 34 per cent, of the total number 

 exammed. The table of details showed a strongly 

 marked positive correlation between the average spleen 

 and the spleen-rate, as exhibited in contiguous 

 columns; but I thought that owing to several sources 

 of error it would not be worth while to work out the 

 relation further. This, however, has now been ably 

 done by Major S. R. Christophers, with the aid of 

 my figures and some of his own. He finds that the 

 very interesting and simple linear relation A=i4-o"o5S 

 holds where A is the average spleen estimated by my 

 rules and S is the ordinary spleen-rate. This is cer- 

 tainly a much simpler function than was to be ex- 

 pected ; but I will not discuss it at present, as a more 

 detailed paper is promised. 



I have no space to mention several other good papers 

 and notes, largely entomological, in the number of 

 Paludism. It is doubtful whether the entomologists 

 will entirely accept the classifications of some of the 

 Culicidae suggested by James and Liston in the second 

 edition of their book. The printing and appearance 

 of the number leave much to be desired. 



Years ago, in 1898, while infecting birds with 

 Proteosoma by the bites of Culex fatigans, I made 

 some observations which showed that such experi- 

 ments might easily be utilised for studying questions 

 of immunity and pathology in malaria. My work was 

 interrupted and never resumed ; but one of the most 

 important sidelights was the following. Out of five 

 sparrows which originally contained a very few 

 Proteosoma, four showed a much more copious infec- 

 tion a week after being subjected to the bites of 

 heavily infected mosquitoes. At the same time the 

 infection of these birds was not so copious as in the 

 case of most of the originally uninfected birds which 

 I had previously dealt with (see my paper in the 

 Indian Medical Gazette, vol. xxxiv., January, 1899). 

 This obviously suggested (a) that fresh bites of in- 

 fected mosquitoes will cause a severe recurrence even 

 in subjects already infected ; but that (b) this recurrent 

 infection, though severe, will not be so severe as an 

 original infection, probably owing to the previous 

 establishment of partial immunity. I have often, 

 fruitlessly, urged the continuation of this line of work. 

 Major Christophers now reports (" Scientific Memoirs, 

 Government of India," No. 46) two more similar ex- 

 periments which, though they are not very convincing, 

 tend to confirm the possibility of such reinfection. 

 But he also gives eighteen experiments which strongly 

 suggest that the severity of the infection in the birds 

 depends largely on the number of, and degree of in- 

 fection in, the mosquitoes — as already probable for 

 theoretical reasons. 



The importance of these points is rendered very 

 manifest by my quantitative studies in epidemiology 

 (see article in >Jatl're. vol. Ixxxvii., p. 467, last para- 

 graph but two), by which it is shown, for instance, 

 that if 50 per cent, of the people are constantly affected 

 under constant conditions, then about 63 per cent, of 

 them will probably be infected or reinfected every four 

 months. In such circumstances it will be extremely 

 difficult to keep down the fever by quinine alone, a 

 fact which explains the failures complained of in 

 Paludism, pp. 7 and 34, and elsewhere. It must 



