368 



NATURE 



[August 20, 1891 



this the inference may be drawn that, in certain cases, at all 

 events, of sleeping sickness a filaria embryo is present in the 

 blood. 



Filaria s. h. diurna and Filaria s. h. perstans have both 

 been found in a case of sleeping sickness. 



These facts taken together amount to a presumptive case against 

 one or other of these parasites as the cause of sleeping sickness. 



The probable life-histories of these worms is then indicated, 

 the Filaria loa being considered the parental form, and an in- 

 sect, called the mangrove fly, the intermediary host of Filaria 

 s. h. diurna. The parental form of Filaria s. h. perstans is not 

 known, but, assuming that the worm of craw-craw, sleeping 

 sickness, and dennatose parasitaire is the same, and that the 

 skin form is an advanced stage of the embryo filaria found in the 

 blood, then, arguing from the analogy to what happens in the 

 case of the embryo of Filaria medinensis, which closely 

 resembles this skin parasite, the probable intermediary host of 

 Filaria s. h. perstatts is a freshwater animal, possibly a cyclops. 



Provided the hypotheses as regards these parasites and the 

 diseases they produce are correct, both disease and parasites 

 may be avoided by securing a pure water supply to which the 

 intermediary hosts of the parasites do not get access. 



Travellers, missionaries, and others in Africa are appealed to 

 for assistance in clearing up the subject, and for further in- 

 formation. 



An appendix to the paper contains directions for demonstrating 

 in the surest, most rapid, and most effective way the presence or 

 absence of filaria embryos in blood, and of making collections of 

 slides of blood for storage and future examination. 



Dr. Sonsino, of Pisa, made a few remarks on Dr. Hanson's 

 paper. The meeting then adjourned. 



On Wednesday, August 12, the chair was occupied suc- 

 cessively by Sir Joseph P'ayrer, Dr. Pistor of Berlin, and 

 Surgeon-General Roth of the Saxon Army. 



Discussion on Diphtheria. 



Dr. Edward Seaton, of London, opened a discussion on 

 "Diphtheria, with special reference to its distribution and to 

 the need for comprehensive and systematic inquiry into the 

 causes of its prevalence in certain countries and parts of 

 countries, with a view to its prevention." 



Dr. Seaton said that he should confine himself in introducing 

 this subject to leading statements, showing the necessity for com- 

 prehensive and systematic inquiry to be promoted by Govern- 

 ment into the causes of the prevalence of diphtheria in certain 

 countries and parts of countries, with a view to its prevention. 

 He first of all pointed to the special prevalence of the disease, as 

 shown by Dr. Longstafi", in Norfolk and Wales, and the com- 

 parative freedom of Devonshire, Cornwall, and the Midlands. 

 He then dwelt on the facts that the disease prevailed more in 

 rural than urban districts, although it has shown of late years an 

 increasing preference for urban populations, especially that of 

 London. He showed the independence of the disease of what 

 are ordinarily called sanitary conditions, and illustrated this by a 

 table taken from Dr. Thome Thome's recent lectures at the 

 Royal College of Physicians, showing the fall in enteric fever 

 mortality in England and Wales which had synchronized 

 with a rise in the mortality from diphtheria. He further 

 illustrated the independence of diphtheria prevalence of 

 what are usually termed sanitary conditions by experiences 

 gathered from a large manufacturing town in the Mi'. lands, and 

 from certain parts of the metropolis in which he had special 

 opportunities for observation as a medical officer of health, as 

 well as in connection with the work of the Metropolitan Asylums 

 Board, into whose hospitals cases of diphtheria had been re- 

 ceived during the last three years. He also gave a recent 

 experience of a Surrey village, in which the disease had pre- 

 vailed in an epidemic form, shortly after the replacement of the 

 old insanitary cesspool system by a new and elaborately con- 

 structed sewerage system. The occurrence of the disease under 

 these circumstances gave rise to the suspicion that there might be a 

 connectionbetweendiphtheria and conditions of soil, which needed 

 to be investigated in a comprehensive and systematic manner. 

 In conclusion, he pointed out the importance of these main con- 

 siderations, viz. : (i) the prevalence of the disease in strikingly 

 difterent degree in countries in the same latitude and with similar 

 climatic conditions and also in parts of countries close to each other, 

 (2) the fact that it has not apparently been influenced favourably 

 by the adoption of sanitary measures which have been generally 



found effective in reducing the death rate, prove the necessity 

 for a comprehensive inquiry by our own Government as well as 

 those of other countries, into the causes which determine the 

 prevalence of diphtheria. Such an inquiry should take into 

 account what has already been ascertained with regard to the 

 occasional causation and spread of the disease by milk, and 

 the influence which schools have on its production and spread, 

 and also the subsidiary influence of dampness, dirt, overcrowd- 

 ing. &c. ; but its main object would be to ascertain the local 

 conditions and circumstances which account for the growth of the 

 disease. To ascertain these the inquiries must, of course, be 

 made in countries marked by freedom from the disease as well 

 as in those which suffer from it specially. 



Dr. Schrevens, of Tournai, followed with a paper entitled 

 " Contribution a I'etude des causes favorisant les endemics 

 diphtheritiques," of which the following is an abstract. 



By investigating carefully how the ravages committed by 

 diphtheria are distributed over the diff"erent districts, one can 

 attain more easily to a precise knowledge of the external con- 

 ditions which favour the harbouring of diphtheritic germs, and 

 which result in such germs being brought into a locality. In- 

 vestigations were made by the author in Belgium with this object. 

 Thanks to the figures kindly furnished by Dr. Kuborn, the 

 distribution of diphtheria throughout the different provinces of 

 Belgium for the ten years from 187 1 to 1880 has been deter- 

 mined. The same having been done for typhoid fever, it was 

 noticed that where this latter disease committed the greatest 

 ravages the same fact was observable in the case of diphtheria ; 

 and that where diphtheria secured its smallest number of 

 victims the number of deaths caused by typhoid fever dimin- 

 ished equally. This parallel rise and fall of the mortality 

 caused tiy typhoid fever and diphtheria is shown in two 

 diagrams placed near each other on the same sheet ; in the 

 first, the parallelism is less evident, because one province. East 

 Flanders, forms an exception to the rule I have just laid down ; 

 in the second diagram this province is omitted, and the parallel 

 march of diphtheria and typhoid fever stands out clearly. On 

 what does this relation, this agreement rest ? On this fact, that 

 these two diseases must be considered as fcecal diseases, as B. 

 Russell, of Glasgow, has remarked. The bacilli of Loffler, like 

 the bacilli of Eberth, develop admirably, prosper, and extend 

 wherever filth and rubbish of all kinds are stored up or spread 

 out ; there exists, however, this slight difference between the 

 conditions which are severally favourable to them : impurities 

 on the stirface of the soil suit the bacilli of Loffler in a special 

 degree, while impurities of the subsoil please the bacilli of 

 Eberth better. 



Even the exception formed by East Flanders tends to confirm 

 this rule, inasmuch as it is perfectly clear that its surface ought 

 to be more easily cleared of all impurities by reason of the 

 numerous watercourses which furrow it. A further proof that 

 it is, in a special degree, impurities of the surface which serve 

 to harbour diphtheritic germs in certain localities, is the ex- 

 aggeration of mortality from diphtheria in country districts com- 

 pared to what obtains in towns ; density of the population is 

 not of the least influence on the increase of the mortality due to 

 diphtheria ; but the surface of the soil is much better protected 

 in towns against impurities of all kinds. 



Another circumstance which may foster diphtheria in a locality 

 is the breeding of certain species of animals presenting a great 

 receptivity for diphtherogenic germs : for example, Italian 

 fowls and game-cocks. The transmission of diphtheria to man 

 by these animals is so well established by the observations col- 

 lected by the author for several years past that he feels per- 

 suaded of the need of further attention being paid to this 

 subject. Finally, a third condition which necessarily fosters diph- 

 theria in a locality is the negligence exercised in the application 

 of measures of disinfection and isolation. 



Every case of diphtheria must be notified to the local 

 authority, who will see to it immediately that all the children 

 of the sick person's family be kept away from school as long as 

 any danger of contagion exists. In every case disinfection 

 must be rigorously attended to and performed by special agents. 

 Notification and disinfection ought to be obligatory. 



The altitude of the locality does not probably exercise any 

 very great influence. One would suppose that diphtheria would 

 be specially prevalent in low, damp places. Recent obser- 

 vations by the author on the progress of diphtheria in three , 

 contiguous parishes of the district of Ath (Giudeghien, Ostiches, 

 and Mainvault), show that in each of these parishes there was a 



NO. II 38, VOL. 44] 



