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