hydatid disease

Echinococcosis: description

Echinococcosis is a worm disease that is usually triggered by the parasitic dog or fox tapeworm. Two very different clinical pictures are distinguished: on the one hand, the alveolar echinococcosis caused by the small fox tapeworm (Echinococcus multilocularis) and, on the other hand, the cystic echinococcosis caused by the small dog tapeworm (Echinococcus granulosus).

While the dog tapeworm is a worldwide problem, the fox tapeworm occurs only in certain regions, including Central Europe and especially southern Germany. In 2014 there were 66 cases of cystic echinococcosis in Germany. 16 people were affected by alveolar echinococcosis, reports the Robert Koch Institute. In these regions, up to 75 percent of foxes are infected with the small fox tapeworm. The average age of onset of fox tapeworm infection is between 50 and 60 years. Children and adolescents are rarely affected. The dog tapeworm triggered echinococcosis affects all age groups.

What are tapeworms?

Tapeworms (Cestodes) are parasites. They consist of a head with mammals and barbs, a neck and a long, band-shaped body. This is divided into individual, similarly structured sections. Tapeworms are hermaphrodites that have no intestines and therefore absorb the food through the skin.

A tapeworm goes through different stages in the course of its development. Depending on the stage, he refers to another host. Carnivorous animals, especially fox and dog, and more rarely cats, pick up the larvae by eating the meat of an infected animal. In the intestine of these end hosts, the larvae develop into tapeworms laying eggs. This happens by always repelling the last limb of his body, which is filled with eggs. A dog tapeworm can lay around 1,500 per section of the body – a fox tapeworm about 200. The eggs are excreted in the faeces and in turn by an intermediate host (for example, mice), where they form a kind of cyst or encapsulation, especially in the liver. Even humans can inadvertently serve as intermediate hosts.

Echinococcosis: symptoms

For many years, an echinococcosis can remain completely unremarkable. During this time the cysts get bigger and bigger and can affect the organs in which they are located. This can reveal an echinococcosis: The echinococcosis displaces or infiltrates organs and leads there to pressure and compression of nerves, vessels or organs. The symptomatology depends strongly on the affected organ. Also an additional infection with bacteria is possible. It can also lead to nonspecific symptoms such as malaise, weight loss and allergic reactions.

liver

In about 70 percent of cases, the liver is affected by an echinococcosis. The consequences are pressure and pain in the right upper abdomen. If the worm infestation obstructs the bile flow, skin and eyes may turn yellow (icterus). This may result in inflammation of the biliary tract (cholangitis), cirrhosis of the liver, and blockage of the portal vein that directs blood into the liver (portal hypertension).

lung

About 20 percent of dog tapeworm infections are in the lungs. In fox tapeworm infections, lung involvement is rare. The main symptom is cough, sometimes bloodier. In addition, sufferers suffer from pain and respiratory disorders.

No organ is protected from an echinococcosis!

Especially in cystic echinococcosis, cysts can occasionally be found in the brain, spleen, heart, bones and other organs. Infestation can be via the bloodstream, the lymph, but also by direct sowing in the abdominal or thoracic cavity.

Echinococcosis: causes and risk factors

For the fox and the dog tapeworm man is a false intermediate host. The larvae nest in various organs, but rarely develop into worms. For those whose immune system is affected by disease or therapy, the disease can be more severe.

The infection with the tapeworms takes place in the vast majority of cases by the food containing eggs from the feces of infected animals. In particular, the consumption of unwashed berries, fallen fruits or fruits of low shrubs carries a high risk of infection. But it is also possible to become infected by eating raw meat.

After ingestion, the eggs usually enter the liver through the intestinal blood vessels. From there they can reach other organs in the course. In the organs, the eggs develop into larvae, which become tumor-like, and perhaps only become noticeable after years.

No transmission from person to person

The disease is not transmitted from person to person. Patients usually do not risk infection. Also, the operated material is considered non-infectious.

Dog and fox tapeworm have very different growth patterns, which are crucial for the different disease patterns of the two worm diseases:

Of the Dog tapeworm makes cysts in the organs. Cysts are liquid-filled cavities. Cysts caused by the dog tapeworm displace the surrounding tissue and are usually single. The cysts cause the body’s own tissue to form a wall around them.

The alveolar echinococcosis by the Tapeworm leads to infiltration of the organs – much like a cancer. They are also spongy and built together by chambering chamber.

Echinococcosis: examinations and diagnosis

First, you should turn to suspected a worm infestation to an infectious. However, the care and treatment of echinococcosis should be done in a specialized center for worm infections. Since one-third of all cases are incidental findings, most patients will be referred to a specialist immediately after the findings are collected. The doctor will, among other things, ask these questions:

• Have you ever been diagnosed with a worm or other parasitic disease?
• Inexplicable abnormalities have been found during previous investigations?
• Do you feel pain or pressure in the right upper abdomen?
• Do you suffer from (inexplicable) diseases of the lungs (eg cough)?
• Are you aware of previous illnesses?
• Which medications do you take?

The most important diagnostic tool in an echinococcosis is imaging. To locate the affected organs, the ultrasound, MRI and CT technique can be used. Due to the frequent calcification of the cysts, they are clearly visible. Thus, foci of cystic echinococcosis are smoothly bordered and calcified especially on the margin. Their daughter cysts typically have a double contour in the wall and a honeycomb structure. Usually, an ultrasound examination is performed first. Already with the help of this examination abnormalities in the liver can be detected. Imaging is so important because a cyst may never be punctured if it is suspected of having an echinococcosis, as this may spread eggs throughout the body.

Further investigations

To clarify an echinococcosis also includes the blood test. In the standard blood test, the rise of a subgroup of white blood cells (eosinophils) may be noticed in around ten percent of cases. It is believed that eosinophils have a role in worm defense. The doctor should send the collected blood to a specialized echinococcosis laboratory. While shipping may take a little more time compared to local lab testing, specialized laboratories can provide better quality results. There, worm-specific antibodies and antigens can be detected and investigated. A negative blood test does not rule out an echinococcosis.

However, no definitive diagnosis can be made both by image and blood tests. Nevertheless, a report to the Robert Koch Institute is always necessary if there are clear findings. For this reason, the final diagnosis should be continued with a reasonable suspicion at an experienced center, such as at the University Hospital Würzburg, the consultation laboratory of the Robert Koch Institute.

The definitive diagnosis can be made by a pathological examination of material taken after surgery. With the aid of the PNM classification, the fox tapeworm infestation can be estimated. This classification takes into account the involvement of the liver (P), the neighboring organs (N) and existing metastases (M).

For therapy monitoring, a special imaging examination, the FDG-PET, can be used. Using this technique, the activity of the worm hydatids can be tested.

More common than an echinococcosis are liver tumors, which can look very similar in imaging. A number of other alternative diagnoses are conceivable. These include different benign and malignant tumors, different types of cysts, abscesses or even tuberculosis.

Echinococcosis: treatment

Treatment of echinococcosis is reserved for specialized centers. It sometimes has to be carried out for years or even for life.

Operational removal

The only healing therapy of the Echinokokkose is according to the current state of the science an operational total removal of the affected areas. This possibility should always be checked. On the other hand, in rare cases a wait-and-see strategy can be considered under close observation.

In cystic echinococcosis, radical cyst removal is attempted or the PAIR procedure is used. In this procedure, 95% alcohol is injected through the skin into the cyst. The PAIR procedure may only be performed after exclusion of a cyst-to-biliary connection and in combination with chemotherapy with albendazole. If echinococcus cysts burst during the procedure, the worm’s breeding capsules may secrete. These can cause a severe allergic reaction. To avoid this, there should be a sufficient distance of about two centimeters between the cysts and the liver surface. In more than 50 percent of the cases complete cyst removal is possible.

The alveolar echinococcosis is also treated with a removal of the herd of worms. However, complete removal is only possible in about a quarter of all cases. In alveolar echinococcosis, drug therapy is more important than in cystic echinococcosis.

In exceptional cases, liver transplantation may be considered.

drugs

In addition or as an alternative to surgery, benzimidazole, such as albendazole or mebendazole, is treated for a prolonged period. An exclusive drug therapy may become necessary if surgery is not possible. These drugs are anti-helminths (antihelmetics) and inhibit the progression of echinococcosis but do not kill it. The good absorption of these drugs is only guaranteed with simultaneous intake of fat. During the therapy regular blood tests with differential blood picture and determination of liver values ​​and creatinine must be carried out.

Contraindications for drug therapy are the risk of cyst rupture. In case of liver diseases and a bone marrow depression, it has to be weighed whether the administration of medication makes sense. Especially in early pregnancy, the therapy should be paused because the drugs can damage the fruit.

In cystic echinococcosis, antihelmetal therapy is given for at least six months if the cysts are inoperable or have complications during surgery. In case of sowing cystic echinococcosis into the abdominal cavity, for example after surgery, albendazole therapy should be given for six months.

Because of the poor prognosis, treatment plans for alveolar echinococcosis are longer. If no surgery is possible, lifelong therapy with anti-worm medication becomes necessary. In case of a successful operation, a drug treatment over two years is recommended.

Echinococcosis: prevention

Any echinococcosis must be reported to the RKI to monitor the infection status.

To protect against echinococcosis, contact with (dead) foxes and foreign dogs in risk areas should be reduced. Own dogs should be dewormed regularly. Dogs imported from southern countries should also be dewormed urgently. Depending on the risk of infection, this should be done in consultation with the veterinarian. The meat inspection and proper disposal of slaughterhouse waste in risk areas are also important basic measures. Raw meat may contain echinococcus.

Fruits from low shrubs and fallen fruits must be washed well. There is a possibility that these are contaminated with tapeworms from Kotresten. Collecting mushrooms and plants in the forest carries a similar risk. The echinococci can remain infectious for months under good conditions. However, short cooking kills them. Even the drying of fruits makes sense. Cooling does not hurt them, however, only temperatures below 80 degrees over several days would kill them – that is at least for the alveolar Echinokokkose secured.

After contact with infected animals, routine checks should be performed four weeks, six, twelve and 24 months. It should also be searched in the blood for antibodies. This allows therapy to be initiated early if necessary. If there is a permanent risk of infection, a check should be made every six months. The fox tapeworm disease is an occupational disease among farmers.

Echinococcosis: disease course and prognosis

Echinococcosis can be fatal. If left untreated, most of the patients die. However, the prognosis of properly treated echinococcosis by dog ​​and fox tapeworm varies widely.

While only 30 percent of the people infected with the fox tapeworm are still alive after ten years, the probability of survival in a dog tapeworm infection is good. This is because fox tapeworm cysts are usually much better to operate on. The complete removal of the Fuchsbandwurmbefalls is rarely possible. A lifelong drug therapy of alveolar echinococcosis, however, can prevent a fatal course. Relapses are always possible. In about 15 percent of all cystic echinococcosis, the disease occurs after a first successful therapy again. Therapy success and disease progression should be monitored regularly with an imaging technique, for example ultrasound, and by measuring antibody levels.

An acutely lethal complication of hydatid disease is the seeding of the larvae, for example by a cyst rupture. Among other things, sowing can lead to peritonitis.