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An Urban Experience
The infection is primarily localised to the liver where metacestodes form multiple cysts and transform the organ into an alveolar, sponge-like structure. After a while protoscoleces are produced and new cysts are formed by exogenous budding. The growth is highly invasive and secondary lesions occurring in e.g. lungs and brain are referred to as metastases. If untreated, the mortality is close to 100%.3,8 In captive primates AE has been documented to be particularly pathogenic and very difficult to control. A recent Swiss study of 23 dogs with AE found abdominal distension to be the predominant clinical sign followed by lethargy, anorexia, vomiting, diarrhoea and weight loss. The median age of the dogs was 3.1 years and most dogs were regularly walked off- leash in rural areas with foxes in the vicinity.3
Excretion of E. multilocularis eggs in the final host
can be detected by copro-ELISA or microscopic examination following flotation or sieving. However, PCR verification is needed while the eggs are morphologically indistinguishable from other taeniid type eggs.
In human medicine, diagnosis of AE is based on clinical findings (abdominal pain, jaundice, and weight loss), imaging (radiology, ultrasonography, computed axial tomography, magnetic resonance imaging) and detection of specific antibodies against E. multilocularis. The diagnosis can be confirmed histologically by identification of parasitic elements or by PCR. Similar methods are applicable in small animal medicine. AE is a differential diagnosis to liver/abdominal tumours.3,8
In humans, the preferred treatment of AE is radical surgical resection combined with long-term benzimidazole treatment. If complete resection of the lesion is impossible, lifelong anthelmintic treatment is indicated.8 Presently, there is no consensus concerning optimal treatment strategies in dogs, but Corsini et
al. suggest: “radical surgical resection and medical treatment or, if total resection is not possible, medical treatment alone.”3
EU legislation governing preventive health measures for control of E. multilocularis allows member states claiming to be free of the parasite to require dogs to be treated against echinococcosis before being allowed to enter the country. Praziquantel is the drug of choice for treatment of definitive hosts. The drug is active against both immature and mature stages of the worm (but not ovocidal!) and should be given 24-120 hours prior to entry into a “free” area. According to the European Food Safety Authorities, treatment should be given: ”as close as possible to entry into a free country” while treatment earlier than 24 hours before entering allows a risk of reinfection before moving.9 Definitive hosts diagnosed with E. multilocularis should
be treated with praziquantel for two consecutive days and eggs should be removed from the fur by thorough washing. Follow-up examination of faecal samples to secure successful treatment is recommended, and the
faeces should be collected and safely destroyed for a period of three days post-treatment. Personnel involved
in handling of infected animals are advised to wear mouth protection, gloves and protective clothing. In endemic regions, deworming at monthly intervals to prevent excretion of E. multilocularis eggs and zoonotic infection is recommended10
Take home messages:
· E. multilocularis is an important zoonotic parasite causing AE and high mortality in intermediate/ accidental hosts if untreated.
· Veterinarians are considered at risk due to close contact with potential definitive hosts (dogs and cats).
· In Europe, E. multilocularis is mainly transmitted in a wildlife cycle with red foxes as the principle definitive hosts, but dogs may be important for zoonotic transmission due to close contact with humans.
· The role of domestic cats is unresolved – may be more important than previously anticipated.
· Prevalence and geographic range of E. multilocularis is expanding and pet travel is likely to be important for the introduction of the parasite into new areas.
· Dogs are the final hosts of the parasite but may also serve as accidental hosts with symptoms similar to AE in humans.
· E. multilocularis is particularly pathogenic to captive primates.
· Current AE therapy: surgery and/or lifelong treatment with benzimidazoles.
· Regular deworming of dogs is recommended in endemic areas to prevent zoonotic infection.
1. Bouwknegt, M. et al. (under review). Prioritization of foodborne parasites in Europe.
2. Knapp, J. et al. (2016). Could the domestic cat play a significant role in the transmission of Echinococcus multilocularis? A study based on qPCR analysis of cat feces in a rural area in France. Parasite 23, 42. Doi: 10.1051/ parasite/2016052.
3. Corsini, M, et al. (2015). Clinical presentation, diagnosis, therapy and outcome of alveolar echinococcosis in dogs.
4. Gottstein, B. et al. (2015). Threat of alveolar echinococcosis to public health – a challenge for Europe. Trends Parasitol. 31, 407-412.
5. Davidson, R.K. et al. (2012). The impact of globalisation on the distribution of Echinococcus multilocularis. Trends Parasitol. 28, 239-247.
6. Oksanen, A. et al. (2016). The geographical distribution and prevalence of Echinococcus multilocularis in animals in the European Union and adjacent countries: a systematic review and meta-analysis.
7. Wahlström, H. et al. (2015). Present status, actions taken and future considerations due to the findings of E. multilocularis in two Scandinavian countries. Vet. Parasitol. 2013, 172-181.
8. World Organisation for Animal Health (Office International des Epizooties) and World Health organization (2001). WHO/OIE Manual on echinococcosis in humans and animals: a public health problem of global concern. pp 1-286.
9. Anonymous (2016). Reconsider timing of E. multilocularis treatment, suggests EFSA. Vet. Rec. 178 (4):79. doi: 10.1136/vr.i327.
10. European scientific counsel companion animal parasites (ESCCAP) (2015). Worm control in dogs and cats. Guideline 01 2nd edition. uploads/docs/nkzqxmxn_esccapgl1endoguidelines.pdf (accessed 12 June 2017)

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