EchinococcosisB67.0

Parasitosis caused by representatives of the genus Echinococcus.

• Dog tapeworm: Echinococcus cysticus = Echinococcus unilocularis = Echinococcus granulosus.
• Fox tapeworm: Echinococcus alveolaris, Echinococcus multilocularis.
• Dog tapeworm in Central and South America: Echinococcus vogeli.

Classification according to pathogen:

• Cystic Echinococcosis (Small dog tapeworm - E. granulosus)
• Alveolar echinococcosis (small fox tapeworm E. multilocularis).

Incidence rare. In Germany, 66 cases of cystic echinococcosis and 16 cases of alveolar echinococcosis were reported in 2004. A previously unquantifiable under-reporting can be assumed.

The genus Echinococcus is characterized by an obligatory host change, in which the sexually mature, very small tapeworms parasitize in the small intestine of end hosts (carnivores, in Europe mainly canine, rarely cats), while the larval stage develops in organs of intermediate hosts (mostly rodents and sheep as well as animals that serve as food for the end hosts). Humans are a classic false host and are attacked by the larval stage of Echinococcus.

In the digestive tract of the intermediate host: larval stage. The larvae migrate through the intestinal wall, infecting mainly the liver, lungs and skin. Development of fertile fins, which are excreted in hydatides with the faeces of the intermediate host and reach the final host by contamination of food or by consumption of parts of the intermediate host.

End hosts (main hosts): For Echinococcus granulosus: dog, fox; wild dogs (dino, jackal, raccoon dog). For E. multilocularis: fox, very rarely also dog or cat. For E. vogeli: small rodents (e.g. agouti paca).

Development of fertilised eggs in the final host and excretion with the faeces into the environment.

• Echinococcus cysticus (unilocularis) = fin stage of Echinococcus granulosus: skin cysts, soft-fluctuating to tight elastic, immovable, painless, up to fist-sized subcutaneous nodules. Clinical symptoms are absent for a long time, finally compression symptoms, palpable tumours, jaundice.
• Echinococcus alveolaris (multilocularis) = fin stage of Echinococcus multilocularis: Destructive growth. In case of skin infestation: Large, blistery tumours with transparent, fluctuating contents, hydatidic whirlpool.

• Cooperation with surgeons and internists.
• The first therapeutic goal is the surgical resection of the cysts by surgeons.
• Preoperatively prophylactic high-dose systemic glucocorticoids (e.g. Solu-Decortin 250 mg i.v.) to prevent anaphylactic reactions to cyst contents in case of rupture. Due to possible degeneration always histological control. Follow-up treatment with mebendazole (e.g. Vermox forte) 40-50 mg/kg bw/day for 3 months.
• If surgery is not possible (often in cases of multilocular echinococcosis), conservative treatment with albendazole (e.g. Eskazole Filmtbl.): 2 times/day 400 mg for 28 days (1st cycle), then 14 days rest, 2nd and 3rd cycle follow in the same way. Alternatively Mebendazole (Vermox forte Tbl.) 1st to 3rd day 500 mg p.o. twice a day, day 4-6: 500 mg p.o. 3 times a day, then 1000-1500 mg 3 times a day. For cystic echinococcosis over 4-6 weeks (possibly repeated), for alveolar echinococcosis up to 2 years. Therapy failures are possible. S.a.u. worm infections.

Prevention and control measures:

• Effective prevention and control measures through close monitoring and analysis of disease and infection in both humans and animals. Educating the population about the risk of infection and general hygiene measures (in particular hand and food hygiene).
• Eggs secreted by infected animals have a very high resistance to environmental influences and disinfectants. They can remain infectious for several months under favourable climatic conditions. In contrast, eggs do not survive short-term boiling and are also very sensitive to dehydration.
• Regular deworming of dogs with praziquantel, meat inspection and proper disposal of slaughterhouse waste are the most important measures to get cystic echinococcosis under control in endemic areas or to maintain the achieved control or eradication.
• All food growing close to the ground which may be contaminated with the faeces of infected end hosts, e.g. berries, mushrooms, vegetables, lettuce and fallen fruit, should be thoroughly washed before consumption and, especially in areas with an increased risk of infection, boiled or dried if possible.
• Hands must be washed thoroughly after working where there has been contact with soil.

Additional pathogen-specific measures may include:

• E. granulosus: Dogs from southern countries should not be brought into Germany, or if they are, they should be dewormed. Irrespective of this, the animal must have a rabies vaccination.
• E. multilocularis: Foxes and tanuki found dead or killed in hunting may only be handled with protective gloves and must be packed in plastic bags for transport. Dogs used by hunters in fox dens should be thoroughly showered afterwards to minimise the risk. Dogs should be kept away from possibly infected prey. Dog faeces that may contain tapeworm eggs should be buried or burned. This applies in principle to the faeces of rodent consuming dogs that are disposed of after tapeworm treatment, especially in high-demic areas. Access by foxes and tanuki to fruit and vegetable crops growing close to the ground should be restricted or avoided by appropriate fencing.

Measures for patients and contact persons

• No specific measures are required for ill persons apart from early diagnosis and, if necessary, initiation of a therapy.
• Contact persons of infected animals (e.g. dog, fox, cat) should be serologically examined after 4 weeks as well as 6, 12 and 24 months after probable contact, as this allows early monitoring and, if necessary, timely initiation of therapy in case of infection. If the risk of infection persists, controls should be continued twice a year. Positive test results must be verified with imaging techniques.

Measures in case of outbreaks

• Outbreaks due to human-to-human transmission do not occur, since there is no human-to-human transmission. It is possible, however, that infected animals could possibly cause a regional increase in the incidence of disease.

The RKI (Robert Koch Institute) is not notified by name of the direct or indirect detection of Echinococcus sp. according to § 7 para. 3 IfSG. The reports must be submitted to the RKI within 2 weeks after the detection of Echinococcus sp.

1. Brainard DM et al (2003) Images in clinical medicine. Thoracic echinococcosis. N Engl J Med 348: 528
2. Chrieki M et al (2002) Echinococcosis--an emerging parasite in the immigrant population. On Fam Physician 66: 817-820
3. Deutz A et al (2000) Echinococcosis--an emerging disease in farmers. N Engl J Med 343: 738-739
4. Kashyap AS et al (2003) Thoracic echinococcosis. N Engl J Med 348: 2156-2157
5. Kodama Y et al (2003) Alveolar echinococcosis: MR findings in the liver. Radiology 228: 172-177
6. Pallas PS (1766) Miscellanea zoologica: Quibus novae imprimus atque obscurae animalium species. Describuntur et observationibus iconbusque illustrantur. Petrum van Cleff, The Hague
7. Redi F (1684) Osservazioni intorno agli animali viventi che si trovano negli animali viventi. Pietro Martini, Florence
8. by Siebold CT (1853) About the transformation of the Echinococcus brood in Taenia. Z Knowledge Zool 4: 409-425