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Echinococcus granulosus - Clinical Manifestation, Complication, Prognosis, Epidemiology, Reservoir, Transmission

Last Modified: February 3, 2023

Clinical Manifestations of Echinococcus granulosus

Echinococcus granulosus is the causative agent of cystic echinococcosis (CE).

Cystic echinococcosis (CE)

  • Cystic echinococcosis (CE) was previously known as hydatid disease

  • the incubation period is highly variable with symptoms appearing even 5 to 20 years after infection

  • in the majority of cases, this condition remains asymptomatic throughout the life

  • if asymptomatic, the cysts can be diagnosed

    accidentally during the x-ray, body scanning, surgery

    when cysts rupture resulting in anaphylactic reactions

    at autopsy

  • in symptomatic cases, Cystic echinococcosis (CE) may manifest variably and depends on

    organs involved

    size of cysts

    sites within the organ involved

    interaction between expanding cysts and adjacent organ

    complications caused by rupture of cysts

  • clinical syndromes of Echinococcus granulosus infection mostly appear after the hydatid cysts reach sufficient size to cause disturbances by mechanical pressure on the surrounding tissues

  • depending upon the vital organs involved, the cysts interfere with functions of the affected organs with chances of fatality

  • in the liver, cystic echinococcosis may present as hepatomegaly with or without palpable abdominal mass which is associated with abdominal pain, nausea, vomiting, portal hypertension, and biliary peritonitis

  • in the lungs, the hydatid cysts are intracapsular and produce signs and symptoms of intra-thoracic growth which may clinically manifest as dry cough, hemoptysis, chest pain, pneumonitis, pneumothorax

  • in other organs such as the spleen, heart, kidney, and brain, the hydatid cysts may present as an abscess or a tumor-like condition

  • in the bone, the Echinococcus granulosus cyst causes rapid erosion of the bone resulting in multiple fractures, and degeneration of bone structures

Complications of Echinococcus granulosus

As a result of trauma or surgery, the Echinococcus granulosus hydatid cysts may rupture into the pleural or peritoneal cavity, and into the pericardium, bile ducts, and gastrointestinal tract. As a result, they produce several clinical issues such as pleural effusion, pneumothorax, and secondary echinococcosis of the peritoneal or pleural cavity.

If hydatid cysts rupture, two risks/complications may be present:

  • sets the free large volumes of hydatid fluid which when absorbed in the circulation, bronchi, pleura, and peritoneum, results in anaphylactic shock which might be fatal

  • if secondary echinococcosis occurs, scolices are disseminated to various parts of the body through the circulation

Prognosis of Echinococcus granulosus

As a spontaneous cure of cystic echinococcosis (CE) is possible, the prognosis of Echinococcus granulosus is good.

Epidemiology of Echinococcus granulosus

Epidemiologically, Echinococcus granulosus is cosmopolitan in distribution.

The parasitic infection is endemic to East Africa, South Africa, Central America, South America, Southeast Europe, Central Europe, the Middle East, Russia, and China. The incidence rate is highest in areas where sheep and cattle are reared.

Reservoir, Source of Echinococcus granulosus

Echinococcus granulosus is a zoonotic disease and man (accidental host) acquires infection from a dog- with the dog being the reservoir.

Two biological forms that have been recognized are the European biotype (cosmopolitan in distribution) and the Northern biotype (areas of Tundra and Taiga).

The source of infection in humans is dog feces containing hexacanth eggs of the parasite.

Transmission of Echinococcus granulosus

Transmission of the Echinococcus granulosus dog tapeworm occurs between man and dog but never from man to man or from one intermediate host to another intermediate host.

Route of transmission includes:

  • direct contact with infected dogs

    infected dog licks anal areas carry the eggs on its tongue and when it grooms itself, the eggs are spread on different parts of its body

    when humans touch or pet the dog, the hands become contaminated which might result in the ingestion of eggs

  • through consumption of food, water, raw vegetables (salads) contaminated with tapeworm eggs

  • through vectors such as the fly

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