taches to the mucosa of the upper small intestine, and develops into an adult tapeworm, which can live for years or even decades. About two to three months after the infection, the first gravid segments detach from the strobila and then appear in feces or they can migrate out of the intestine without defecation. The segments remain motile for some time and frequently leave the stools.
Pathogenesis and clinical manifestations. In some infected persons, T. saginata causes morphological changes (villus deformation, enterocyte proliferation, cellular mucosal infiltration, etc.) and functional disturbances. Blood eo-sinophilia may occur sometimes. The infection takes an asymptomatic course in about 25 % of cases. Symptoms of infection include nausea, vomiting, upper abdominal pains, diarrhea or constipation and increased or decreased appetite. Infection does not confer levels of immunity sufficient to prevent reinfection.
Diagnosis. A Taenia infection is easy to diagnose if the 1.5-2 cm long and 0.7 cm wide segments are eliminated in stool (Fig. 10.7c, d). Morphological species differentiation (T.saginata vs. T. solium) is often not possible based on the gravid proglottids, but can be done by DNA-analysis (PCR). T. saginata eggs are shed irregularly in stool and cannot be differentiated morphologically from T. solium eggs (Fig. 10.1, p. 544). Using an ELISA, coproantigens are detectable in stool fluid even when neither proglottids nor eggs are being excreted.
Therapy and prevention. The drug of choice is the highly effective praziquantel. Albendazole, mebendazole, and paromomycin are less reliable. The main prophylactic measures are sewage treatment and the detection of cysticercus carriers at inspection of slaughter animals. Meat containing numerous cysti-cerci ("measly meat") has to be confiscated, but meat with small numbers of cysticerci can be used for human consumption after deep-freezing that is lethal to the parasites. Individual prophylaxis consists of not eating beef that is raw or has not been deep-frozen.
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