The Life History of Diphyllobothrium Mansonoides Mueller, 1935, and Some Considerations with Regard to Sparganosis in the United States 1

Abstract

Summary 1. The procercoid develops in Cyclops leuckarti, C. viridis, C. bicuspidatus, and becomes infective in from 18 to 21 days. 2. Mice of various species are found regularly susceptible to oral infection. Guinea pigs, rats, rabbits, birds, cats, and monkeys are generally resistant to oral infection with procercoids. 3. Certain hosts, generally resistant to oral infection, such as the rat, cat, etc., can be infected by hypodermic injection of the procercoids. 4. Resistance appears to be of two types. That occurring in rats appears to be located in the alimentary canal since they cannot be infected orally but can be infected by injection. That in frogs and birds appears to lie in the tissues themselves since they cannot be infected even by injection. 5. The morphology of adult worms raised from spargana from various intermediate hosts is constant and typical. 6. The definitive hosts are the cat, bobcat, and occasionally the dog. 7. Infection in the cat with the adult worm produces marked emaciation, anemia, nervousness, and permanent stunting. 8. Cats which have been long infected develop a resistance to the parasite which shows itself in diminished egg production, impaired viability of the eggs produced, and marked diminution in size of the worms. 9. Mice infected with spargana pass through an acute stage, lasting about 2 months, during which time the coat is rough, the eyes inflamed, and emaciation apparent. Mice surviving this stage pass into a chronic condition and resume normal appearance. 10. The rat does not show external signs of infection. In this host the spargana are smaller, and their heads usually surrounded by a bloody area. 11. In monkeys, infected by injection, no signs are apparent during the first 2 months. After this period, however, elephantiasis of the affected part may develop. The swellings are filled with a slimy gelatinous mass. 12. In all hosts the migration of spargana is attended by extensive tissue damage and pathology. 13. Experiments on transplanting spargana suggest the possibility that the mouse and snake strains of D. mansonoides may be separate. 14. D. mansonoides differs from mansoni in that it does not infect frogs, rabbits or birds, and appears to thrive better in the cat as a definitive host than in the dog. 15. D. mansonoides appears to be worthy of consideration as a probable cause of sparganosis in man in this country. Over a large section of the country, man must be continually exposed to infection wherever drinking water from natural sources is used. 16. The sparganum does not undergo asexual reproduction or proliferation in the tissues.