Tropical diseases of the urinary tract

Abstract

ANY WIDESPREAD TROPICAL DISEASES such as malaria, yaws, and cholera do not involve the urinary tract except in a very secondary fashion and do not merit consideration in this paper. However, there are diseases that commonly involve the kidneys, ureter, and bladder. The most frequent of these is infection with Schistosomo haematobium. Others requiring consideration are filariasis and the relatively rare hydatid disease of the kidney. GENITOURINARY SCHISTOSOMIASIS Genitourinary schistosomiasis does not occur naturally in the Western Hemisphere. When it does occur, it is in patients who have resided in endemic areas: South, Central, and North Africa. It is particularly common in Egypt and occurs in parts of Israel, southern Turkey, northern Syria, Iran, Iraq, and Cyprus. It has been reported in southern Portgual and in the Bombay State area of India. Pathogenesis and Life Cycle The disease was thought to be caused by parasitic infestation with S. haemutobium; however, recent work suggests that it is not due to one species, but to a group of them.1 Different Schistosoma species have varying geographic distribution and produce different clinical manifestations in the urinary tract. For instance, in Rhodesia where the prevalent species is S. capense, urinary obstruction from fibrosis of the bladder neck is rare and Schistosoma eggs have not been recovered in biopsy material from the testis and epididymis. In Egypt, where bladder neck fibrosis and ova in the genital tract are both common, the offending species is S. haematobium. The Schistosoma has a complicated life cycle. In the case of genitourinary schistosomiasis, the ova are deposited by the female worm in the bladder wall and ulcerate through it to be voided with the urine. These ova mature in water into miracidia which enter a species of snail, Bulinus. In the liver of the snail, they mature into cercaria which are then shed from the snail. The parasite invades man either in drinking water, or during bathing through small abrasions on the skin. It enters the systemic venous circulation, passing from the right heart through the lungs to the left heart. It then enters the systemic circulation and, after a varying period in the liver, enters the portal circulation and passes to the vesical and pelvic venous plexuses where the female deposits her eggs.