120 THE AMOEBAE LIVING IN MAN 



which have often been sent to me for identification. The largest series 

 of cases from which [ can form an approximate estimate of the preva- 

 lence of this organism is that which I examined at Epsom {vide Dobell, 

 Gettings, Jepps, and Stephens, 1918). Here I examined 1,300 men and 

 found 29 infections. As the cases were examined on the average only 

 twice each, it is certain that more were really infected. If the results 

 can be interpreted — as seems highly probable from the figures at my 

 disposal — in the same manner as the findings of E. histolytica {vide 

 Dobell, 1917), then the whole series was probably infected to the 

 extent of some 4 or 5 per cent. My figures also appear to indicate 

 that infections with /. biitschlii are commoner in persons who have 

 been in the tropics and the Near East than in those who have been 

 in France and the British Isles only. 



Wenyon and O'Connor (19 17) have published statistics showing the 

 incidence of infection in various groups of people examined by them in 

 Egypt. The figures ran;,e from 2 per cent, up to i4"8 per cent. — the 

 latter being the figure for natives in Hadra Prison. The percentages are 

 derived from series examined only once per case on the average, and are 

 therefore all too low. They were — with one exception — always lower 

 than the percentage infections with E. histolytica. In my experience the 

 frequency of /. biitschlii as compared with E. histolytica infection for the 

 same group of cases lies as a rule between i : 3 and 1:5. It is certainly 

 the least common of the intestinal amoebae of man (except Dieiitaiuocba), 

 but probably occurs — so far as I can judge — in at least some 3 to 5 per 

 cent, of all human beings. 



It is a curious fact that /. bi'itschlii very frequently occurs in company 

 with E. histolytica — far too frequently for it to be due to chance. When 

 not accompanied by this species, it is generally in company with E. coll 

 or E. nana, and all the four species occur together fairly often. I have 

 not yet found with certainty a single pure infection with /. biitschlii. 

 There can be no doubt that it is an entirely independent species, how- 

 ever ; and I can offer no plausible explanation of its almost invariable 

 association with other amoebae. 



Pathogenicity. — Although /. biitschlii has usually been found in 

 the stools of persons who have previously suffered from dysentery or 

 other intestinal disorders, this is probably merely because the stools of 

 healthy people are not usually investigated. I have found infections in 

 healthy people with no history of dysentery or persistent diarrhoea. 

 Wenyon and O'Connor (1917) have found the cysts in the faeces of 

 healthy white troops and natives in Egypt, and Matthews and Malins 

 Smith have found them in residents in the British Isles. There is 

 at present no evidence that the organism is pathogenic, and it seems 

 almost certain that it is not. 



Treatment. — One of the most remarkable characters of /. bi'itschlii is 

 its prompt disappearance when emetine is administered to its host. 

 Wenyon and O'Connor (1917) noted that emetine hydrochloride given 

 either hypodermically or by the mouth to infected persons causes the 

 cysts to vanish from their stools. In none of their cases did they sub- 

 sequently reappear during the period of observation. I have found that 

 the administration of emetine bismuth iodide has the same effect, 

 and have already recorded the apparent cure of 5 cases by this means 

 {-vide Dobell, Gettings, Jepps, and Stephens, 1918). I have studied other 

 cases, both before and since, and some who were treated with emetine 



