Disease: Echinococcosis (alveolar form)

This page provides general information about this condition; reveal the text by clicking on  the green headers. Press releases, results from DWHC investigations as well as other useful documents and relevant literature can be found at the bottom of the page.

Pathogen

Alveolar echinococcosis is a parasitic disease affecting certain species of mammals including rodents, humans and canids. It is caused by infection with the larval form of a species of a species of Echinococcus tapeworms. In Europe several forms of Echinococcus worms are found and are responsible for different forms of Echinococcosis. The alveolar form of this disease, is caused by Echinococcus multilocularis which is endemic in many parts of Europe.

Susceptible species

Dogs and other wild canids such as foxes and raccoon dogs as well as, to a lesser extent, cats are the definitive hosts (intestinal infection with egg-producing adult worms) of these worms but may occasionally also develop the cystic form of the disease (i.e. intermediate hosts). In the usual life cycle, rodents act as intermediate hosts for the larval forms of this parasite which form cysts in the internal organs. The cycle is completed when these infected rodents are eaten by a definitive host and adult worms attach to the intestines releasing eggs into the feces.

Signs in animals

Infection of the definitive host can be asymptomatic however, in rare cases, when very large numbers of the worms are present the intestines may become blocked and there may be signs of anal irritation.

Infection of animals

Definitive hosts i.e. dogs and other canids, become infected through eating raw or under-cooked meat containing Echinococcus cysts. Farm or hunting dogs that have access to slaughtered carcasses or their offal are most at risk.

Intermediate hosts become infected via ingestion of foodstuffs that have been contaminated by the feces of infected definitive hosts.

Symptoms in people

Humans may become infected by ingestion of the tapeworm eggs that are found in the feces of infected dogs. The main routes of infection include consumption of water or fruit and vegetables that are contaminated by dog feces or direct contact with infected dogs.

Infection of people

In humans infected with E. multilocularis, it can take years for clinical signs to develop and these tend to reflect impaired function of the organ(s) in which the larval cysts have formed; typically the liver and lungs.

Geographical distribution

Due to changing environmental and socioeconomic factors the distribution of E. multilocularis continues to increase and has to-date has been reported in most countries of Northern (excluding Norway and Finland) and Western (with the exception of Spain and Portugal) Europe, with strikingly few regions of Southern Europe reporting cases.

Beyond Europe, E. multilocularis is endemic in many countries of the Northern hemisphere including parts of the US, Canada, China and Russia.

Preventative measures

Pet owners are advised to de-worm their dogs and cats (especially animals that hunt rodents) regularly to minimse the risk of infection being transmitted from pets to humans. In some areas where the disease is endemic, local authorities use baits containing wormers to attempt to minimise the level of infection in wild animals and stray dogs.

When foraging for wild fruits and nuts be aware of the possibility that these may be contaminated with the feces of infected carnivores.

Other strategies for control include improving awareness amongst farmers, hunters and the general public; and performing continued surveillance of disease levels in wildlife populations.

References
H Enemark, M Al-Sabi1, J Knapp, M Staahl, M Chríel. Detection of a high-endemic focus of echinococcus multilocularis in red foxes in southern Denmark. Eurosurveillance (2013) 18:10
M Janovsky, L Bacciarini, H Sager, A Groene, and B Gottstein, Echinococcus multilocularis in a European beaver from Switzerland: J. Wildl. Dis. 38:3, 618-620
WHO/OIE Manual on Echinococcosis in Humans and Animals: a Public Health Problem of Global Concern Eds. J. Eckert, M.A. Gemmell, F.-X. Meslin and Z.S. Pawłowski. World Organisation for Animal Health (Office International des Epizooties) and World Health Organization, 2001

External information

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