Echinococcus is an infection caused by the Echinococcus granulosus or Echinococcus multilocularis worm.

Echinococcus is common in southern South America, the Mediterranean, the Middle East, central Asia, and Africa. In the United States, the disease is very rare, but has been reported in California, Arizona, New Mexico, and Utah.

Humans become infected when they swallow eggs in contaminated food. The infection is carried to the liver, where cysts form. Cysts can also form in the lungs, as well as in the brain, bones, skeletal muscles, kidney, spleen, and other tissues. A liver cyst may produce no symptoms for 10 to 20 years until it is large enough to be felt by physical examination or to produce symptoms.

Risk factors include exposure to cattle, sheep, pigs, or deer or exposure to the feces of dogs, wolves, or coyotes.

• abdominal pain in upper right quadrant
• severe itching of skin
• cough
• bloody sputum
• chest pain
• fever

A physical examination may reveal abdominal pain, involvement of other organs, skin signs, and occasionally, shock.

The following tests may be done to determine the presence and location of the cysts:

• Chest x-ray
• Thoracic CT scan or ultrasound
• Abdominal X-ray
• Abdominal CT scan or ultrasound
• Blood test for antibodies to echinococcus
• Liver function tests

Most often, echinococcosis does not cause symptoms and is found accidentally when an imaging test is done for another reason.