Dibothriocephalus latus

Hashemite University

Diphyllobothrium Latum

Course : Parasitology _ Advanced

Instructor : Dr. Naim Ismail

Presenter : Belal Abu Haneya

Outline• Classification

• Introduction

• Morphology

• Symptoms

• Diagnosis

• Treatment

Classification

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.

Diphyllobothrium latum at Tadas Ivanauskas Zoological Museum

Life cycle

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