Hymenolepsis nana

Hymenolepsis nana
(Dwarf tapeworm)
1- Causes Hymenolepiasis (Dwarf tapeworm infection).
2- The disease in humans is primarily limited to children in warm climates. It s prevalent throughout India, parts of Latin America, Asia, Hawaii.
3- H. nana is the smallest of tapeworm of man. The entire worm has a length of only 25-40mm.
4- The egg is round to oval. The centrally located hexacanth embryo is equipped with the standard three pairs of hooklets.
A shell complete with polar thickening protects the embryo. Numerous polar filaments originate from the polar thick thickening, which in addition to size, help to distinguish it from the egg of H. diminuta.
5- The scolex contains 4 suckers, short rostellum armed with one row of hooks helps to distinguish it from that of H. diminuta which has no hooks at all.
6- The mature and gravid proglottids resembles those of H. diminuta, the worm has 200.
When eggs are swallowed, they hatch in the duodenum, and the liberated embryos penetrate into the stroma of villi, where in 5-6 days they transform into cercoid larvae. These then attach to the mucosa, and in about 2 weeks they develop into complete worms.
Thus, both the larval and adult stages develop in the same individual.
Moreover, in heavy infections it seems entirely probable that internal auto infection may have occurred as a result of hatching of eggs in the upper level of the small intestine regurgitation into the stomach. H. nana also can utilize fleas for the development of the cysticercoid stage.
Lab diagnosis:-
This is done by examining stool samples for characteristic eggs.