TREMATODES 513 



into man, and develops into a sporocyst which then infects a patient with 

 its young. 



It has been assumed that man becomes infected with the parasite by drink- 

 ing infected water. Yet the observations and the experimental investigations 

 of Loos make this assumption doubtful. Attempts to infect monkeys by 

 giving them infected water to drink did not prove successful. Brock and Loos 

 assume that the parasites gain access directly through the skin during bathing. 

 Men and boys are affected much more frequently than women and girls who 

 bathe but rarely. Brock found that the newly arrived in the Transvaal who 

 went bathing were soon infected, whereas others who did not bathe remained 

 free from the parasite. Loos rejects, however, the assumption of Harley and 

 Allen that the parasite finds entrance into the body through the urethra. 

 The incubation period, according to Loos, is four weeks; according to Brock, 

 four months. 



In addition to the parasites at the points of predilection in the vascular 

 system, autopsies reveal the most marked changes in the bladder and in the 

 ureters. In freshly developed cases there is a marked catarrh of these organs 

 with a viscid, yellowish-red mucus in which, as also in the mucous membrane 

 itself, numbers of distoma eggs are found. In chronic cases the mucous 

 membrane shows the signs of a severe chronic catarrh, and has a sandy ap- 

 pearance. Characteristic excrescences, from the size of a pea to that of a 

 bean, and having the appearance of hemorrhagic ecchymoses, are formed in 

 the swollen submucous tissue. The excrescences sometimes become encrusted, 

 and then represent stony polypi which are broken off and form the nuclei 

 of bladder stones. Pyelitis, nephritis and hydronephrosis follow in severe 

 cases. Kartulis, Albarran-Bernard and Harrison quote cases from their expe- 

 riences which show in the tissues permeated with distomata the tendency to 

 proliferation, that is, to formation of carcinoma. Not the parasites, but the 

 ova, cause the severe irritation. They are also found in the lungs, in the 

 liver, in the prostate gland and in the mesenteric glands. 



Clinically we encounter at first the manifestations of a hematuria asso- 

 ciated with burning pain in the urethra. At first intermittent, it gradually 

 becomes permanent. The characteristic ova are found very early in the urine. 

 If the infected individual does not leave the country, the disturbance is aggra- 

 vated by affections of the renal pelvis and of the kidneys. Stones in the 

 bladder and in the kidneys develop frequently. We have mentioned the 

 tendency to the formation of carcinoma. Cole Madden describes a papilloma 

 ■of the vagina produced by the ova of distoma. The mucous membrane of the 

 rectum shows similar polypoid excrescences as the bladder. The nutrition 

 becomes defective and, finally, after a course lasting years, death occurs with 

 cachectic manifestations. It seems that severe cases are most frequent in 

 Egypt. In South Africa, after protracted intermittent attacks of hematuria 

 and cystitis, the disease often, at least apparently, ends in recovery. The 

 destruction of the parasite does not in itself lead to recovery. Sonsino esti- 

 mates the duration of its life at two to three years. If the changes have been 

 very extensive, the morbid symptoms continue to develop after the death of 



the parasite. 

 34 



