Molecular testing for Echinococcus granulosus is used for the diagnosis and laboratory documentation of echinococcosis.
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Echinococcosis, also referred to as hydatidosis or hydatid disease, is a parasitic infection common among patients who come into contact with sheep or bovine animals and affect more than 1 million people worldwide. Echinococcus species are tapeworms (Cestodes) and the two most important species that infect humans are Echinococcus granulosus and Echinococcus multilocularis.
In terms of geographical distribution, Echinococcus granulosus can be found all over the world, in rural areas where dogs can feed on dead infected sheep or cattle while Echinococcus multilocularis is found mainly in the northern hemisphere. The final hosts for E. granulosus are dogs or other canids and the final hosts for E. multilocularis are foxes and to a lesser extent, other canids. Adult Echinococcus worms are located in the small intestine of the final hosts and release their eggs that pass into the feces, which can be ingested by a vector, usually sheep or cattle in the case of E. granulosus or small rodents in the case of E. multilocularis. Eggs hatch in the small intestine releasing the echinococcus that penetrates the intestinal wall and migrates through the circulatory system to various organs where the cysts develop. The final host becomes infected after ingestion of these infectious cysts. People become infected accidentally after ingestion of Echinococcus eggs.
In humans, E. granulosus cysts usually develop in the lungs and liver, and the infection may remain silent or latent for years (5-20 years) before cyst size increases and symptoms appear. Symptomatic manifestations include chest pain, hemoptysis, cough in the case of pulmonary involvement and abdominal pain, and obstruction of the bile duct in the case of liver infection. Hydatid cyst rupture can cause fever, urticaria, and anaphylactic shock.
Diagnosis of echinococcal infections is based on characteristic findings by ultrasound or other imaging techniques and serological testing. It is important to note that infected people do not release parasite eggs in their stools.
