Echinococcosis, cystic echinococcosis, and fox tapeworm

Echinococcosis is an infection caused by infestation with a fox tapeworm or a small dog tapeworm.

There are two types of the disease:

• The fox tapeworm (Echinococcus multilocularis) causes what is known as alveolar echinococcosis
• while the small dog tapeworm (Echinococcus granulosus) causes cystic echinococcosis

The fox tapeworm is found primarily in the southern parts of Europe and Germany, while the dog tapeworm is found worldwide.

Each year in Germany, 80 people contract the dog tapeworm and 54 contract the fox tapeworm. Most of these people are between the ages of 50 and 60. Children are affected only very rarely.

Echinococcosis does not necessarily cause symptoms. It can remain undetected for years. During this time, cysts can grow in the organs, which, once they reach a certain stage, can impair a person’s well-being.

The cysts manifest as a vague feeling of pressure and can compress nerves and blood vessels.

Additional symptoms that may occur:

• Infections
• Nausea
• Weight loss
• Allergy symptoms

People in southern Germany or travelers in Italy, Spain, or other southern countries are at higher risk of contracting fox tapeworm disease.

Be careful not to come into contact with fox feces, which can be found on forest floors, for example. 

Avoid eating wild berries, windfall fruit, or mushrooms found in the forest. Raw meat can also be a source of infection.

Dog owners can have their pets dewormed regularly. Alternatively, a test of the dog’s feces can be performed to rule out an infestation. Generally, dog owners are only at higher risk if they live in poor sanitary conditions. Worm infestation is also promoted by feeding raw meat, particularly sheep offal. Additionally, working with sheep professionally can be a risk factor.

If you think you may be infected, you should consult a specialist in infectious diseases. Specialized medical centers and clinics are also equipped to diagnose the condition.

During an initial consultation, the doctor will determine:

• Whether you have ever had worms or other parasites
• Whether there were any other unusual symptoms
• Whether you experience pain or pressure in the upper right abdomen, and 
• Whether you have an unexplained cough

It is also important to note any pre-existing conditions and medications you are taking.

To definitively diagnose echinococcosis, the doctor uses imaging techniques. 

The following are used:

• Ultrasound
• Magnetic resonance imaging (MRI)
• Computed tomography (CT)

Using ultrasound, the doctor can first detect calcified cysts. Calcification and the smooth border of a cyst are typical signs of cystic echinococcosis. The cyst must remain intact to prevent the release of worm eggs.

To confirm the diagnosis, the doctor performs a blood test. A worm infestation often causes an increase in white blood cells (eosinophils). This increase indicates that the body is mounting a defense. A specialized laboratory tests the blood sample for echinococcosis. It can detect specific antibodies. 

A negative result does not mean that echinococcosis is absent. A positive result, however, confirms the disease and must be reported. The doctor must submit the results to the Robert Koch Institute.

There are several options for treating cystic echinococcosis:

• In some cases, the doctor will initially adopt a wait-and-see approach. This is the case when the cysts are not causing any problems. Otherwise, the doctor treats the infection with medications containing albendazole.
• Follow-up examinations are conducted to assess the success of the treatment. If liver cysts develop, doctors can remove them surgically. 
• Another option is the injection of high-proof alcohol (95%) into the cyst. This method is only considered if there are no fistulas present.
• In inoperable cases, the doctor treats alveolar echinococcosis with benzimidazoles. Treatment may be lifelong. If surgery is possible, the accompanying drug therapy with benzimidazoles lasts at least two years.

If echinococcosis is suspected, the appropriate specialists to consult are physicians specializing in infectious diseases. Veterinarians specializing in parasitology are also qualified to treat this condition.

The insidious nature of this infection is that it can take up to 15 years for symptoms to appear. In both forms of echinococcosis, the tapeworm larvae do not remain in the intestines but migrate to other organs.

Alveolar echinococcosis (Echinococcus multilocularis) is an infection caused by the fox tapeworm. It is very rare but can be fatal. The tapeworm eggs first colonize the intestinal wall and then the liver. There, the larvae form a sponge-like tumor that slowly destroys the tissue. The lungs, brain, and peritoneum may also be affected. It can take at least five years before pain develops in the upper abdomen. By then, surgical removal is no longer possible. The mortality rate for fox tapeworm echinococcosis ranges between 50 and 70 percent.

In about 70 percent of cases, the liver is affected by echinococcosis @ Dr_Microbe /AdobeStock

Cystic echinococcosis (Echinococcus granulosus) is caused by the dog tapeworm. This form is more common but less dangerous. These tapeworm eggs also penetrate the intestinal wall, colonizing the liver, possibly the lungs, and, rarely, other organs. 

However, this does not result in tumors, but rather in clearly defined cysts. These are usually detected during an imaging examination. They, too, can cause pain in the upper abdomen. Cystic echinococcosis is benign and resolves on its own.

Cystic echinococcosis is often associated with solitary (liver) cysts @ Dr_Microbe /AdobeStock

What is echinococcosis?

Echinococcosis is a parasitic disease caused by tapeworms. The causative agents are Echinococcus granulosus (the dog tapeworm) and Echinococcus multilocularis (the fox tapeworm). Echinococcosis in humans results from ingesting eggs that are excreted in the feces of definitive hosts such as foxes or dogs.

What is the difference between cystic and alveolar echinococcosis?

Cystic echinococcosis usually forms a large, closed cyst, often in the liver or lungs. Alveolar echinococcosis involves infiltrative growth within the tissue and clinically resembles a tumor. The course, prognosis, and treatment of cystic and alveolar echinococcosis differ significantly.

What are the symptoms of echinococcosis?

Early symptoms are often absent in echinococcosis. The first symptoms usually arise from large cysts in the liver or from involvement of the lungs and brain. Nonspecific symptoms such as a feeling of pressure, pain, or organ dysfunction may occur, depending on the location of the cysts.

How is echinococcosis diagnosed?

The diagnosis of echinococcosis is based on imaging techniques such as MRI and serological detection of antibodies. The diagnosis takes into account clinical findings and the typical location of the cysts. Detection is often achieved through specific tests for the pathogen.

How is echinococcosis treated?

Treatment for echinococcosis depends on the form of the disease and the extent of the infection. In cases of cystic echinococcosis, surgical removal of large cysts may be necessary. In addition, drug therapy with albendazole or mebendazole is used. Long-term drug therapy is often required, particularly for alveolar echinococcosis, as this form is more aggressive. In many countries, echinococcosis is a notifiable disease because it is widespread worldwide, particularly in Mediterranean countries and the Balkans.