The most common symptoms are nocturnal anal pruritus (pruritus ani) and sleeplessness, presumably resulting from the migratory female worms. Vaginitis and salpingitis may develop secondary to aberrant worm migration. The eggs are detected by microscopically examining adhesive cellophane tape pressed against the anus in the morning to collect eggs. Less commonly, a worm may be seen in the perianal region. Treatment is with albendazole (400 mg), mebendazole (100 mg), or pyrantel pamoate (11 mg/kg, maximum 1 g) each given as a single oral dose and repeated in 2 weeks.
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Schistosomiasis (bilharziasis) is caused by flukes that parasitize the bloodstream, including Schistosoma haematobium, Schistosoma mansoni, Schistosoma japonicum, and, rarely, Schistosoma intercalatum and Schistosoma mekongi (Table 123-3). Schistosomiasis affects more than 2 million people, mainly children and young adults with a peak age range of 10 to 20 years. Humans are infected by cercariae in contaminated water that emerge in an infectious form from snails and penetrate intact skin. Each adult worm migrates to specific sites:
S. haematobium to the bladder plexus and S. intercalatum and
S. mekongi to the mesenteric vessels. The eggs are deposited by the adult flukes in urine (S. haematobium) or stool (S. mansoni
Echinococcosis Echinococcus granulosus var.
Alveolar echinococcosis Echinococcus multilocularis Surgical resection is only reliable means of treatment; some reports suggest adjunct use of albendazole or mebendazole
Neurocysticercosis Larval stage of Taenia solium Ingestion of infected raw/ Albendazole or praziquantel (cysticerci) undercooked pork
Adult tapeworm infections T. solium (pork tapeworm) Ingestion of contaminated raw/ Praziquantel undercooked pork and S. japonicum). S. haematobium is prevalent in Africa and the Middle East; S. mansoni in Africa, the Middle East, the Caribbean, and South America; S. japonicum in China, the Philippines, and Indonesia; S. mekongi in the Far East; and S. intercalatum in West Africa.
The manifestations of schistosomiasis result from eggs that are trapped at the site of deposition or at metastatic locations. Within 3 to 12 weeks of infection, while the worms are maturing, a syndrome of fever, malaise, cough, abdominal pain, and rash can occur. This syndrome is followed by a resultant inflammatory response that leads to further symptoms. Katayama fever is an acute condition, with fever, weight loss, hepatosplenomegaly, and eosinophilia. Eggs may be found in the urine (S. haematobium) or stool (S. mansoni and S. japonicum)of infected individuals. Sanitary measures, molluscacides, and therapy for infected individuals may help control the illness.