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Echinococcus is an infection caused by the echinococcus multilocularis worm, which is a parasitic tapeworm. The infection is rare in the United States. It occurs more often in the Middle East, Africa, Central Asia, and the Mediterranean.
A few different types of tapeworms can cause echinococcus. In some instances, the organs affected by the infection depend on which type of tapeworm has caused the infection. The three forms of infection that can occur in humans are: E. granulosus, E. multilocularis, and E. vogeli.
The cause of echinococcus is infection by a tapeworm. The parasite enters a host, which is usually an animal, such as a dog, sheep, or goat. The worm lives in the bowels of the animal. The worm then releases eggs into the feces of the animal. For humans, the most common means of transmission is eating food that has been accidentally contaminated with animal feces. After eating contaminated food, the incubation period, which refers to how long before symptoms start, is usually a few months. Certain strains of the parasite can have a longer incubation period, up to a few years.
One risk factor for contracting the parasite is being exposed to the feces of dogs, cattle, pigs, and sheep. Cases of the infection have been reported in the United States, but the risk is higher in countries where the parasite is more common.
Symptoms vary depending on which organs are affected. According to Stanford University, about 75 percent of people who develop the infection have liver problems. Symptoms often include pain in the abdomen and the formation of cysts on the liver. About 22 percent of people have respiratory symptoms because the infection affects the lungs. Symptoms may include chest pain and coughing up bloody mucus. Other areas of the body can also be affected, including the skin, spleen, and kidneys (Stanford University).
Medical tests and an examination of the symptoms can help diagnose the infection. A chest X-ray will rule out other types of infection. An abdominal MRI or CT scan may also be used in order to make a diagnosis. Because the incubation period can be long, the parasite is sometimes discovered while testing for other reasons.
Certain medications can destroy the parasite. The treatment used may depend on the severity of symptoms.
Medication is almost always used to treat echinococcus and may include mebendazole or albendazole. The parasite can also cause inflammation of the organs. Anti-inflammatory medication is also used to treat this.
In some instances, when cysts are present, surgery may be recommended. According to the National Institutes of Health, surgery is complicated and may not be recommended in all cases.
If the infection has affected the brain, fluid can accumulate. A shunt may be placed to drain fluid from the brain.
The prognosis depends on the extent of the infection and on the organs of the body involved. In some instances, cysts may rupture, which can be life threatening. According to the National Institutes of Health, if the cysts are reduced and respond to the medication, the outlook is often good.
There are several different ways to prevent an echinococcus infection. In areas of the world where the parasite is common, education can help. Removing the worms from dogs can reduce the chances of infection. In addition, proper handling of cattle at farms and slaughterhouses, which includes enforcing meat inspection procedures, is essential to prevent the infection.
Correct disposal of animal feces can also reduce exposure to tapeworm eggs.
Washing fruit and vegetables, especially in areas where the tapeworm is common, can also reduce infection. Avoiding undercooked or raw beef, pork, and fish can also help prevent echinococcus.
Written by: MaryAnn DePietro
Published on: Jan 07, 2014
Medically reviewed on: Jun 02, 2016: Judi Marcin, MD
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