Small fox tapeworm, dog tapeworm
Echinococcus multilocularis, Echinococcus granulosus
Profile
Echinococcosis in humans is a disease caused by the larvae of the tapeworm genus Echinococcus. The small fox tapeworm, Echinococcus (E.) multilocularis, the causative agent of alveolar echinococcosis, is found only in the northern hemisphere. The dog tapeworm, E. granulosus, the causative agent of cystic echinococcosis, is found worldwide.
Occurrence
The small fox tapeworm is found in numerous European countries, but particularly in Austria, Germany, Switzerland and France. In Bavaria and North Tyrol, it is found on average in one in every three to four foxes, and in Vorarlberg in almost one in every two foxes.
The dog tapeworm is found worldwide, with a higher prevalence in Eastern Europe, the Mediterranean region and the Balkan states. In Austria, there are currently no known cases of dogs being infected with the dog tapeworm, but the incidence is thought to be very low.
Route of infection
Small fox tapeworm: These parasites, measuring 2–3 mm in length, live in the small intestine of foxes and, rarely, in cats and dogs. Infectious eggs are excreted into the environment via the faeces. If these tapeworm eggs are ingested by suitable intermediate hosts (e.g. small rodents such as mice) whilst feeding, infectious tapeworm heads, known as scolexes, develop in the intermediate hosts’ organs, particularly the liver. If a person – humans act as accidental intermediate hosts for these parasites – inadvertently ingests these microscopic eggs, the larvae can develop and infiltrate the liver tissue, much like a malignant tumour, forming what are known as alveolar cysts. This condition is known as alveolar echinococcosis.
Dog tapeworm: These worms, measuring 3–6 mm in length, live in the small intestine of dogs. Every one to two weeks, they shed the final tapeworm segment, which contains up to 1,500 eggs and is excreted into the environment with the faeces. These tapeworm segments or eggs are ingested by intermediate hosts (sheep, goats, cattle, pigs) whilst grazing. The eggs develop into larvae, which pass through the intestinal mucosa into the bloodstream and on to the liver and other organs (e.g. lungs, heart, spleen), where they grow into bladder-like structures known as ‘finns’ or cysts. Thousands of ‘headlets’ form within these cysts, each of which can develop into a new tapeworm as soon as tissue containing the cysts is eaten by a dog. In humans, as in intermediate hosts, the condition is known as cystic echinococcosis. Humans become infected via soil-borne or contact transmission by ingesting Echinococcus eggs from fox or dog faeces.
Symptoms
Alveolar echinococcosis: The most common symptoms are pain in the upper abdomen and jaundice; fatigue, weight loss or an enlarged liver, caused by cancerous growth of the parasitic tissue, may also occasionally occur.
Cystic echinococcosis: Pain in the upper right abdomen is common, caused by encapsulated cysts in the liver measuring up to 30 cm. The rarer form affecting the lungs is characterised by breathing difficulties and a cough.
Therapy
The aim of treatment is the complete surgical removal of the Echinococcus cysts; however, this is usually no longer possible, or only with great difficulty, at an advanced stage. Treatment therefore involves a combination of surgery and antihelminthic chemotherapy.
Cystic echinococcosis: The PAIR technique is available for treatment: puncture (P) guided by ultrasound or computed tomography, aspiration (A), instillation (I) of substances that kill the tapeworm heads, and reaspiration (R) of the cyst contents, in conjunction with antihelminthic therapy.
Prevention
Echinococcus eggs are highly resistant to environmental factors and disinfectants and can remain infectious for several months.
To prevent infection with E. multilocularis, hands should be washed thoroughly after working with soil and grass. Dogs should be wormed regularly and properly. Ensure good hand hygiene is practised when in contact with dogs. Foods that grow close to the ground (such as vegetables, mushrooms, berries or windfall fruit) should be washed thoroughly before eating or, if possible, boiled. Wear gloves when handling dead foxes or fox droppings.
To prevent infection with E. granulosus, dogs should be regularly dewormed and should not be fed offal from infected sheep.
People at increased risk of infection (e.g. hunters, farmers, vets, laboratory staff) should be tested annually for specific antibodies against Echinococcus spp. antigens (‘serological prophylaxis’).
Small fox tapeworm: The small fox tapeworm is primarily a tapeworm of the fox (including the golden jackal, raccoon dog and wolf), and less commonly of dogs and cats, with various species of mouse (field mouse, bank vole, vole, grass mouse), musk rats and other small mammals as intermediate hosts. The adult tapeworms live amongst the intestinal villi of the small intestine mucosa of foxes and feed on their host’s semi-digested food. Several thousand E. multilocularis specimens can be found in the small intestine of a heavily infected fox. Despite this large number of parasites, an infected fox shows no visible signs of illness. The final segment of the tapeworm can contain several hundred infectious eggs, which are excreted into the environment via the fox’s faeces. If these microscopic eggs are ingested by intermediate hosts whilst feeding, small larvae hatch in the gut, penetrate the intestinal wall and travel via the bloodstream to the liver. In these highly susceptible intermediate hosts, fluid-filled cysts (tapeworm cysts) develop in the liver, containing numerous tapeworm head buds (scolices). An infected mouse falls ill within a few weeks, becomes lethargic and is easy prey for the fox. If the infected intermediate host is then preyed upon by the final host, the fox, a new generation of tapeworm develops within it, capable of producing infectious eggs after just 4 weeks. Egg shedding can continue for several months. In the external environment, the eggs of E. multilocularis survive for 2–3 months during the summer in Central Europe if there is sufficient moisture, and for up to 8 months in cooler seasons.
The small fox tapeworm is primarily of significance to humans, who act as accidental intermediate hosts in the parasite’s life cycle. The accidental ingestion of these microscopically small eggs usually leads to the development of organ-destructive parasitic tissue, typically in the liver of infected individuals. As detached clusters of cells are carried via the bloodstream, distant metastases may occur, for example in the lungs or the brain, similar to those seen in a malignant tumour. It can take 5–15 years from the time of infection until the first symptoms appear. In humans, the disease is known as alveolar echinococcosis; it occurs predominantly in older people and presents with symptoms similar to those of a liver tumour.
In rare cases, dogs may also contract alveolar echinococcosis as accidental intermediate hosts.
Recent studies carried out at the NRL for Parasites at the AGES Institute for Veterinary Medical Investigations in Innsbruck revealed a prevalence (infection rate) of E. multilocularis in foxes of 45% in Vorarlberg, 33% in Tyrol, 16% in Salzburg and 19% in Carinthia. In Austria, infection with E. multilocularis in foxes, dogs and other canids must be reported to the relevant district administrative authority in accordance with the AHL.
Dog tapeworm: The adult worms live in the small intestine mucosa of dogs or other carnivores. Every one to two weeks, they shed the final tapeworm segment, which contains up to 1,500 eggs and is excreted into the environment with the faeces. These tapeworm segments are ingested by intermediate hosts (sheep, goats, cattle, pigs) whilst grazing. The eggs develop into larvae, which pass through the intestinal mucosa into the bloodstream and on to the liver and other organs (e.g. lungs, heart, spleen), where they grow into bubble-like structures known as cysts. Thousands of ‘headlets’ form within these cysts, each of which can develop into a new tapeworm as soon as tissue containing the cysts is ingested by a dog. In humans, who act as accidental intermediate hosts for this parasite, the condition is known as cystic echinococcosis. Humans become infected via soil- and grease-borne transmission by ingesting E. granulosus eggs from dog faeces.
In Austria, the prevalence of E. granulosus infection in dogs is currently unknown, but is assumed to be very low.
The organs and muscles of all slaughtered animals, which may also be potential intermediate hosts of echinococci, are examined for the presence of tapeworm segments and cysts during official post-mortem inspection.
Contact
Institut für Veterinärmedizinische Untersuchungen Innsbruck
- vetmed.innsbruck@ages.at
- +43 50 555 71111
-
Technikerstraße 70
6020 Innsbruck
Last updated: 19.06.2026
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