- Hymenolepis

The class Cestoda consists of endoparasitic organisms which are usually segmented and have tape-like morphology. Cestoda species that infect humans include members of the order Cyclophyllidae and members from the order Pseudophyllidea of the family Diphyllobothridae. Cyclophyllidean cestoda includes Anoplocephalidae, Davaineidae, Dilepididae, Taeniidae, Hymenolepididae, and Mesocestoidae [1]. Adult tapeworm is transparent and consists of head, and body made up of short segments called proglottids. The head or the scolex is armed with hooks, “suckers,” or both. There are different types of suckers. Some types of “suckers” are called bothria or bothridia. Bothria are usually slit-like grooves as seen in Diphyllobothrium species. Another type of sucker-like organ is the cup-like acetabulum. Scolex of cestodes has sensory organs, and nerves which are attached longitudinally extend down the body. These nerve ‘bers are attached to various parts/organs and the cestode is able to detect tactile stimulation [2]. Below the scolex is the neck and the body or strobila with segments whose width is more than their length. The

genital pores are unilateral, or on either side of the segment. The short segments are called proglottids. The proglottids can be classi‘ed as immature, mature, and gravid. Each mature proglottid encompasses a complete set of male and female reproductive organs and the genital opening (vaginal canal) opens to the outside. Self-fertilization, involving the sexual structures of a single proglottid, or cross-fertilization between proglottids of the same worm may occur. Some proglottids in mature strobila may become sexually undifferentiated due to the crowding effect [3]. Crowding effect possibly prevents parts of the strobila from coming into contact with the mucosa of the host from which they receive necessary nutrition and protein-synthesizing enzyme. When a proglottid becomes old and unable to absorb any more nutrition, it is released and is passed through the host’s digestive tract. A gravid proglottid contains fertilized eggs, which are sometimes expelled with the feces. However, most of the time, the egg settles in the microvilli of the small intestine, hatch, and the larvae can develop to sexual maturity without ever leaving the host. The life cycle of Hymenolepis can be

24.1 Introduction ..................................................................................................................................................................... 265 24.1.1 Classi‘cation ........................................................................................................................................................ 266

24.1.1.1 Family Hymenolepididae ...................................................................................................................... 266 24.1.2 Clinical Manifestation and Pathogenesis ............................................................................................................ 267

24.1.2.1 Disease Pathogenesis ............................................................................................................................ 267 24.1.3 Immunology ......................................................................................................................................................... 268

24.1.3.1 In Vivo Models for Studies on Hymenolepis Immunology ................................................................... 268 24.1.3.2 Immunobiology of Hymenolepis nana in Mouse System ..................................................................... 268 24.1.3.3 Immunobiology of Hymenolepis nana in Rat System .......................................................................... 269 24.1.3.4 Role of Eosinophils ............................................................................................................................... 269 24.1.3.5 Immunobiology of Other Hymenolepis spp. Infection ......................................................................... 269

24.1.4 Diagnosis ............................................................................................................................................................. 269 24.1.4.1 Conventional Techniques ...................................................................................................................... 269 24.1.4.2 Molecular Techniques ........................................................................................................................... 271

24.2 Methods ........................................................................................................................................................................... 272 24.2.1 Sample Preparation .............................................................................................................................................. 272

24.2.1.1 Collection of Parasite Material ............................................................................................................. 272 24.2.1.2 Puri‘cation of DNA from Human Feces .............................................................................................. 272 24.2.1.3 Puri‘cation of DNA from Adult Worms of Hymenolepis .................................................................... 272

24.2.2 Detection Procedures ........................................................................................................................................... 272 24.2.2.1 Detection Procedure Using ITS1 .......................................................................................................... 272 24.2.2.2 Detection Procedure Using Mitochondrial CO1 Gene ......................................................................... 272

24.3 Treatment of Hymenolepiasis .......................................................................................................................................... 272 24.4 Conclusion and Future Perspectives ................................................................................................................................ 273 References ................................................................................................................................................................................. 273

brie›y and broadly described as follows: (a) eggs are ingested by de‘nitive hosts, (b) eggs hatch in the duodenum releasing oncospheres and lie in the lymph channels of the villi, (c) oncospheres develop into a cysticercoid, which has a tail and a well-formed scolex, and it attaches to the small intestine and matures into an adult, (d) gravid proglottids then release and pass out through feces along with eggs or eggs can hatch and infect the original host and start the cycle again within the gut itself, and ‘nally, (e) eggs are excreted to the environment that are ingested by insects or rodents [4] for further transmission. It has been shown that cysticercoid burden reaches a plateau depending on the host’s nutritional status. An interesting feature of Hymenolepis tapeworms is that they undergo a diurnal migration within the gut which is associated with the feeding patterns of the host.