FISH TAPE WORM DISEASE : CLINICAL ASPECTS
Most infected patients are asymptomatic. On occasion, however, they have complained of epigastric pain, abdominal cramping, vomiting, and weight loss. Moreover, the presence of several adult worms within the gut has been known to precipitate intestinal or biliary obstruction. Forty percent of fish tapeworm carriers demonstrate low serum levels of vita-min B12, apparently as a result of the competition between the host and the worm for in-gested vitamin. Studies have shown that a worm located high in the jejunum may take up 80 to 100% of vitamin B12 given by mouth. Approximately 0.1 to 2% of patients develop macrocytic anemia. They tend to be elderly, to have impaired production of intrinsic fac-tor, and to have worms located high in the jejunum. In many, folate absorption is also diminished. Lysolecithin, a tapeworm product, may also contribute to the anemia. Neuro-logic manifestations of vitamin B12 deficiency occur, sometimes in the absence of anemia. They include numbness, paresthesia, loss of vibration sense, and, rarely, optic atrophy with central scotoma.
The diagnosis is established by finding the typical eggs in the stool. As D. latum produces
large numbers of ova, identification is usually accomplished without the need for concentration techniques.
Treatment is carried out as described for T. saginata infections. When anemia or neurologic manifestations are present, parenteral administration of vitamin B12 is also indicated. Personal protection can be accomplished by thorough cooking of all salmon and freshwater fish. Devotees of raw fish may choose to freeze their favorite dish at -10°C for 48 hours before serving. Ultimately, control of diphyllobothriasis is accomplished only by prohibiting the discharge of untreated sewage into lakes and streams.