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Hashemite University
Diphyllobothrium Latum
Course : Parasitology _ Advanced
Instructor : Dr. Naim Ismail
Presenter : Belal Abu Haneya
Comparison between Pseudophyllidea and Cyclophyllidea
Pseudophyllidea Cyclophyllidea
Scolex 2 slit-like sucking 4 cup-shaped suckers (bothria) with or without hooks
Genital on the flat surface on the margin of the pore of the segment segment
Intermediate 2 1 host
Introduction
• Dibothriocephalus latus, or Diphyllobothrium latum is a fish tapeworm
• most common in waters of the Northern Hemisphere
• infests humans and other mammals that eat fish, particularly bears and dogs
• measuring 10 meters in length with 4000 proglottids *
• * a segment of a tapeworm containing both male and female reproductive organs
• Fertilized eggs pass from the host’s body in the feces
• In a water medium they develop into a hair-like larva
• eaten by tiny crustaceans, which, in turn, are eaten by a fish
Morphology
• The adult worm is composed of three segments: * the scolex (head) * the neck * the lower body
• Each side of the scolex has a slit-like groove, which is a **bothrium for attachment to the intestine.
• The scolex attaches to the neck, or proliferative region.
• From the neck grow many proglottid segments which contain the reproductive organs of the worm.
* elongate, dorsal or ventral longitudinal grooves on the scolex of cestoda
• D. latum is the longest tapeworm in humans, averaging ten meters long. Adults can shed up to a million eggs a day.
• In adults, proglottids are wider than they are long (hence the name broad tapeworm).
• As in all pseudophyllid cestodes, the genital pores open midventrally.
Clinical symptoms
• Symptoms of diphyllobothriasis are generally mild, and can include
DiarrheaAbdominal painVomitingweight lossFatigueConstipation Discomfort
• Approximately four out of five cases are asymptomatic and may go many years without being detected
• In a small number of cases, this leads to severe vitamin B12 deficiency due to the parasite absorbing 80% or more of the host’s B12 intake
• anemia can also lead to subtle demyelinative neurological symptoms
Diagnosis
• Diagnosis is usually made by ..
* identifying proglottid segments
* characteristic eggs in the feces
• these simple diagnostic techniques are able to identify the nature of the infection to the genus level, which is usually sufficient in a clinical setting
• when the species needs to be determined (in epidemiological studies)
restriction fragment length polymorphisms ( RFLP )can be effectively used
* PCR can be performed on samples of purified eggs
* or native fecal samples following sonication of the eggs to release their contents
• Another interesting potential diagnostic tool and treatment is
• the contrast medium, Gastrografin
• introduced into the duodenum
• allows both visualization of the parasite
• shown to cause detachment and passing of the whole worm.
Treatment
• The standard treatment for diphyllobothriasis, as well as many other tapeworm infections is
• single dose of Praziquantel, 5–10 mg/kg PO once for both adults and children
• An alternative treatment is Niclosamide, 2 g PO once for adults or 50 mg/kg PO once for children
• Praziquantel is not FDA approved for this indication and
• Niclosamide is not available for human use in the United States.
Epidemiology
• People at high risk for infection have traditionally been those who regularly consume raw fish.
• Many regional cuisines include raw or undercooked food including
• sushi and sashimi in Japanese cuisine• carpaccio di persico in Italian• tartare maison in French-speaking populations• ceviche in Latin American cuisine• marinated herring in Scandinavia.
• With emigration and globalization..
• the practice of eating raw fish in these and other dishes has brought diphyllobothriasis to new parts of the world and created new endemic foci of disease
References• Muratov, IV; Posokhov, PS (1988). "Causative agent of human
diphyllobothriasis--Diphyllobothrium klebanovskii sp. n.". Parazitologiia 22 (2): 165–70
• Yamane, Y; Kamo, H; Bylund, G; Wikgren, BJ (1986). "Diphyllobothrium nihonkaiense sp. nov (Cestoda: Diphyllobothriidae)---revised identification of Japanese broad tapeworm". Shimane J Med Sci 10: 29–48