In the United States, it is most commonly encountered in persons living in the southern states, in institutionalized patients, and in children. Unlike the other tapeworms, the larval and adult stages of H. nana develop in the same host. Infection is spread by the fecal-oral route and occurs when eggs, which are immediately infectious, are ingested. Eggs are liberated from the distal segments of the adult worm, which lives for about one year. The eggs may cause internal reinfection.
Diagnosis is made by finding eggs in feces.
Infection is more common in children and is associated with few or no symptoms. Children are also more commonly infected with the dog tapeworm Dipylidium caninum . Infection is acquired by consuming infected fleas or lice. Adult worms develop in the small intestine and measure 15 to 70 cm in length. Mild intestinal symptoms may or may not be present.