January 13, 1916] 



NATURE 



55A 



sealed in the Arlington trials was the susceptibility 

 1 the receiving stations to induction from mar-by 

 jwer circuits or electrical apparatus. With the pre- 

 nt limited use of wireless, this latter trouble can 

 • avoided by carefully choosing the sites of receiving 

 ations, but it would become a serious factor if the 

 -e of wireless telephony became general. Mr. Col- 

 jjitts predicts the use of wireless telephony for long- 

 distance communications. Thus a transoceanic tele- 

 phone cable is not an engineering or commercial 

 possibility; and to enable, say, America to talk to 

 Europe or Asia, wireless telephony will be the means 

 chosen. In extending the possibilities of wireless com- 

 munication between ships at sea there is a field for 

 telephony, while from ship to shore \\Ircless telephony 

 is the only possibility. 



THE TRANSMISSJOX OP HIl.HARZlA 

 DISEASE BY SNAILS.^ 



THE cause of Bilharzia disease of man was dis- 

 covered by Bilharz in 185 1, and it is only n6w, 

 more than half a century later, that the mode of trans- 

 mission has been discovered. The disease is due to 

 the presence of flukes in the mesenteric and vesical 

 veins, or, rather, it is in the main the eggs which 

 these worms lay that cause the inflammation which 

 has such dire consequences. The cause being known, 

 helminthologists of repute then naturally sought to 

 determine how infection arose. It was known that 

 the eggs hatched in water into ciliated embryos, and 

 from what was also known of the life-histor}' of other 

 flukes, it was natural to conclude that in this case 

 also the embryos next entered into the tissues of some 

 fresh-water mollusc. This could be shown in two 

 ways, either (l) by experimentally infecting molluscs 

 with the larval forms (ciliated embryos), or {2) by 

 dissecting molluscs from an endemic area and finding 

 the larval forms in them. All attempts in these direc- 

 tions proved in vain. But it is astounding- to learn 

 in this report that whereas some fifty species of fresh- 

 water molluscs occur in Egypt, only nine species are 

 recorded as having been examined by the various 

 observers who took up the problem". Nine' species out 

 of fifty! One cannot help adding that these observers 

 really deserved their bad luck n 'i m Imvo' by .u cident 

 stumbled on the right mollusc. 



Before, however, we proceed tu describe h< i\\ Dr. 

 R. T. Leiper, who conducted this expodttipUr found the 

 intermediate host (mollusc) we should .point out at 

 what stage our knowledge had previously arrived. 



In Japan there exists in man and dogs ?i "Bilharzia " 

 disease due to a different species of fluke,, hut to oiv 

 belonging to the same genus. Japanese workers had 

 shown that dogs could be infected by standing them iri 

 the water of flooded fields of infected areas, but not in 

 water containing simply ciliated embryos,' and thev 

 noted that the invading form difi'ered so much from 

 the ciliated embryos that an intermediate host seemed 

 probable. Further, in iqi3 it was announced that a 

 reproductive sta(?e of this fluke had been found in 

 Lymnaeus sp. Mice were also infected from the water 

 in which snails had lived, these having been pre- 

 viously infected with larval stages. These results were 

 fullv confirmed and extended by Leiper and Atkinson 

 in Japan. The problem of the Egyptian bilharziasis 

 was now ripe for solution, and we see in the present 

 report how rapidly Leiper and his colleagues effected 

 it. On p. 23 it is stated the mission found bilharzia 

 worms in three species out of eight of the commonest 

 fresh-water molluscs within half an hour's train 

 journey from Cairo ! - 



1 Report on the Rr'iihsof th- Bilharzia Mission in Egypt. 1915 Kv 

 Temp^rirv L'eui»nant-Col'->ne1 R. T Leiper. Journal of the Ko\al Army 

 Medicil Corp*. July and Ai)gu«t, 1915. (London: John Ba'e. Sons, and 

 Danie'sion ) 



Other workers aware of the Japanese results were 

 also attacking the problem. In July, 1915, Causton 

 and Warren published the results of their experiments. 

 Though they hesitated in forming a definite conclusion^ 

 it now appears certain that the cercariae they found 

 in Physopsis africaua were those of bilharzia. 



To return to the present report. At El Marg,. 

 a village where the only water supply is a 

 branch of the fresh-water canal from Cairo to 

 Ismailia and Port Said, forty-nine out of fifty-four 

 boys of about twelve years of age were found to be 

 infected. Fifteen species of molluscs were found in 

 the canal when the water in the latter was turned off, 

 which occurs for a fortnight every three weeks. The 

 commonest species were Planorbis boissyi, bullinus, 

 and Cleopatra spp. The two former species "attracted " 

 ciliated embryos of bilharzia eggs when these were 

 presented to them in water. 



P. boissyi was so commonly infected with bilharzia 

 cercariae (larval forms) that large quantities of cercariae 

 could easily be collected. Rats were successfully in- 

 fected with these cercariae, and the adult worms were 

 found in the portal veins. An examination of the eggs 

 proved them" to be the human species. Experiments 

 on monkeys now showed that the oral as well as the 

 cutaneous modes 'of infection occurred, but the oral 

 probably means mucosal and not gastric. The incuba- 

 tion period was one-two months in these animals, as it 

 is in man. The main fact has now been discovered. 

 There will remain the working out of details. Further 

 work will be necessary on the life-history of the snails,, 

 and it will perhaps be wise to wait until we know 

 this thoroughly before precise measures of prophylaxis 

 are advocated, but we may point out some of the 

 factors bearing on the problem. 



The disease is commoner in the Delta and in the 

 Fayum than in those parts of Egypt supplied with 

 "basin" irrigation. For instance, as Madden has 

 pointed out, Ghizeh furnishes to Cairo hospitals only 

 about ten cases per 100,000 population, while Sharkieh 

 furnishes twenty, Qaloubieh eighteen, and Menoufieh 

 about tliirteen. These latter provinces have perpetual 

 irrigation, while Ghizeh has basin irrigation. ^ The 

 probable explanation is that perpetual irrigation 

 favours the development of snails. 



There are 30,000 children born annually in Cairo ; 

 10,000 of these, it is said, become infected. How? 

 Cairo has two water supplies, a filtered, and an un- 

 filtered derived from, the Nile. Now water that has 

 been taken from the Nile and used for agriculture as 

 a rule does not re-enter the Nile, but is removed by 

 drains which eventually reach the sea, but south of 

 Cairo a number of these drains re-enter the Nile, so- 

 that this is a possible source of infection of Cairo by 

 its nnfiltered water. Cercariae, however, can only be 

 kept alive experimentally for thirty-six hours in water, 

 and it is calculated that if the water has entered more 

 than thirty miles upstream the cercariae should be 

 dead before they reach Cairo. As regards the infec- 

 tion in Cairo, one would like to have the actual proof 

 of the finding of cercariae in the unfiltered water from 

 the pipes. The opinion is expressed that storage for 

 1^-2 days of this unfiltered water would protect Cairo. 

 In villages, the principle involved is a simple one, viz., 

 turning off or diverting^ the water from a particular 

 canal, with the result of killing the molluscs, but the 

 problem is complicated by a consideration of the agri- 

 cultural aspect of such a procedure. 



It is at present premature to indicate exactly 

 how this can be best done ; a very careful studv of the 

 life-history of snails will, as we have said, be neces- 

 sary, but we have no doubt that Ecrypt can at last be 

 freed from the scourge of bilharzia, evidence of the 

 ravages of which has been found even in the mummies. 



J. W. W. S. 



NO. 241 1, VOL. 96] 



