Faculty of Allied Medical Sciences Parasitology (MLPR-201) fall 2013/2014

Protozoan Parasites Cestodes Dr. Hamdy  Badie M. El-Wakil Prof. of Parasitology & Public Health . Faculty of Allied Medical Sciences. Pharos University In Alexandria,Egypt

Intended learning outcomes By the end of this lecture students should understand cestodes:Classification Position, Name of the parasite,Description ( Morphological Characters in vivo), Definitive (Final) Host, Intermediate Host, Mode Of Infection, Infective Stage, Habitat, Diagnostic Stage ,Disease, and life cycle.

(b) Class: Cestodes The cestodes (tapeworms) are ribbon-like, segmented worms that are primarily intestinal parasites. They totally lack a digestive system, and thus do not ingest particulate matter, but instead absorb soluble nutrients directly through their cuticale. In the small intestine some species, for example, the tapewarm Diphyllobothrium latum, can attain enormous lengths of up to fifteen meters.

Cestodes cause clinical injury by sequestering the host’s nutrients, by excreting toxic waste, and, in massive infestations, by causing mechanical blockage of the intestine. The anterior end of the worm consists of a scolex, a bulbous structure with hooks and suckers that functions to attach the worm to the intestinal wall.

The body (strobila), is composed of many segments called proglottids, which form continuously in the region just behind the scolex. Each proglottid has a complete set of sexual organs –both male and female– that generate fertilized eggs. The mature, egg- filled proglottids are located at the posterior end of the organism. These can break off of the chain, and pass out of the body in the stool.

Note that Taenia solium has to different disease manifestations, depending on whether transmission is by ingestion of larvae from under cooked pork, or by ingestion of its eggs. In the former case, infestation is limited to the intestines, whereas in the latter case, the eggs develop into larvae that form cysts (cysticerci) in the brain and other tissues.

Each proglottid has a complete set of sexual organs –both male and female– that generate fertilized eggs. The mature, egg-filled proglottids are located at the posterior end of the organism. These can break off of the chain, and pass out of the body in the stool. Note that Taenia solium has to different disease manifestations, depending on whether transmission is by ingestion of larvae from under cooked pork, or by ingestion of its eggs. In the former case, infestation is limited to the intestines, whereas in the latter case, the eggs develop into larvae that form cysts (cysticerci) in the brain and other tissues.

Taenia solium (Pork-tape worm)

Life cycle of Taenia saginata (Beef tape worm)

Life cycle of Taenia saginata (Beef tape worm)

Pathology and clinical features: Usually there is no pathology as Cysticercus bovis is unknown in humans. Occasionally there is vague alimentary upset

Distribution: Taenia saginata is found in beef-eating areas, especially in tropics. Laboratory diagnosis: Gravid segments, ova and scolex can be found in faeces. Uterine branches of the mature segments may be seen in a crush preparation between two glass slides, or found on the perianal skin (on clear adhesive tape slides.

Dwarf tape worms Hymenolepis nana

Intraosseous cyst Intraosseous cyst. Spreads along medulla by budding outside cyst. Semisolid; no fibrosis

Study questions What is the difference between the Life cycle of Taenia saginata (Beef tape worm) and Life cycle of Taenia solium (Pork-tape worm)?

Assignments Group of students will be selected for an assignment topic ,one of the parasites that are studied in your course. The following points should be covered in your assignment sheets: (1) Classification Position: (2) Name of the parasite; (3)Description ( Morphological Characters in vivo): (4) Definitive (Final) Host: (5) Intermediate Host: (6) Mode Of Infection: (7) Infective Stage:-. (8) Habitat:- (9) Diagnostic Stage:- (10) Disease:- (11) life cycle

Assignments Anopheles Mosquito سهىهشامبدرعباس سهيلهنبيلحامدعبدالقادر سوزانعبدالحميدآدمعوض شاهندهعنترمحمدفتوح حازممحمدعليفراجعثمان كاريمانمحمدزكريامحمدابراهيم مختاررائدعبدالكريم كيرلسعصامفرج  

Culex Mosquito شروقأسامةمحمدعلي صلاحالدينمحمدالسيدالسيدسيداحمد   شروقأسامةمحمدعلي صلاحالدينمحمدالسيدالسيدسيداحمد صهيبمحمدعبدالكريمعطيهسيداحمد عائشةعليحسنالشناوي محمدصلاححساناحمد محمدعاطفعبدالعالآبوالجود محمدنبيلمحمدابراهيمسالم ايمانمروانشوربجي

Recommended text books: World Health Organization, Geneva. Basic laboratory methods in medical parasitology. 1991. Larry Roberts and Jr.,John Janovy. Foundations of Parasitology. 2009 Burton J. Bogitsh and Clint E. Carter. Human Parasitology. 2010