Parasitology - Hymenolepiasis

HYMENOLEPIASIS caused by Hymenolepis nana H. diminuta Hymenolepis nana (dwarf tapeworm) • Adult worm measures 1-4.5 cm in length. • four suckers and armed with one row of hooks • In the mature segment, there are three testes in the middle H. nana…… anatomy H. nana……. Infective stage and mode of infection • The egg, which is immediately infective when passed by the patient • It is rounded, about 40 microns in diameter • contains a six- hooked oncosphere within a rigid membrane (the embryosphere) - This embryosphere has thin filaments called polar filaments H. nana……….mode of infection/life cycle • Ingestion of egg with contaminated raw vegetables • Direct infection from a patient • Auto infection: the eggs of H. nana are infective as soon as they are passed with feces by the patient. …persistence - If the hands of the patient are contaminated by these eggs, she/he infects herself/himself again and again.