Sparganosis

SPARGANOSIS, a helminthiasis caused by the larval stage of the cestode Diphyllobothrium mansoni Cobbold, 1889. Since the decoding of the latter's developmental cycle, it has been established that Sparganum is its plerocercoid. (The biology is similar to Diphyllobothrium latum, see Tapeworms). Sparganosis is prevalent in Japan and China; in the USSR, it has not yet been registered in humans; it has been found in the tapeworm stage in arctic foxes on the Commander Islands (A. M. Petrov, 1933). Man is an auxiliary host, in whom the parasite in the plerocercoid stage (the so-called Sparganum mansoni) inhabits various organs: under the peritoneum, in the urethra, eye, lungs, etc. The size of the plerocercoids is 8–60 cm. The intermediate host is Cyclops leuckarti, and the definitive hosts are the dog and the arctic fox. Besides humans, plerocercoids have been discovered in frogs, snakes, and some other vertebrates, by eating which dogs become infected. Humans become infected either by swallowing an infested cyclops with water or, following a custom common in China and Japan, by applying frog muscles to inflamed areas for medicinal purposes. It has been experimentally proven that plerocercoids can actively invade human tissues in this process. The development of plerocercoids in tissue is associated with edema, swelling, and soreness of the affected area. Upon autopsy, the affected focus is found to be filled with a viscous substrate, sometimes with a chylous exudate. Treatment of sparganosis consists of extracting the plerocercoid from the tissue and healing the wound. The prognosis depends exclusively on the localization of the plerocercoid, the number of parasites, and whether it can be removed without harm to the host. Prevention consists of boiling drinking water in areas endemic for D. mansoni and in combating the custom of applying frog muscles to inflamed areas. In addition to S. mansoni, Sparganum proliferum (Ijima, 1905) has been confirmed in humans in the same geographical areas. The latter is characterized by a branched form, which distinguishes it from S. mansoni, for which an unbranched form is characteristic. The intermediate and definitive hosts for Sparganum proliferum are not known. Yokogawa (1933) expresses doubt regarding the independence of Sparganum proliferum, assuming its identity with S. mansoni. Experimentally, however, this question has not yet been resolved.