Does the following sound familiar? While walking in the woods, you find yourself admiring all of mother nature‘s gifts – many of which look more than delicious: … But you cannot help but think to yourself: „I better not pick the ones close to the ground”. After all, we have been taught to fear the fox tapeworm. According to current knowledge, however, infections via contaminated hands play a much more important role, either following direct contact with infected definitive hosts (fox, dog, cat), which may carry the eggs in their fur, or handling contaminated soil. But what’s behind this danger?
Tapeworms (Echinococcus)
The fox tapeworm (Echinococcus multilocularis) and the dog tapeworm (Echinococcus granulosus) are two parasites of the Echinococcus (E.) genus. While E. multilocularis only occurs in the northern hemisphere, E. granulosus is spread all around the world, in Europe especially in the Mediterranean countries and the Balkans.
As part of their natural development the parasites undergo a host change: In the intestines of their definitive hosts, usually foxes or dogs, they develop from larvae into adult, mature worms. Their eggs are excreted with the faeces and ingested by intermediate hosts such as rodents or ruminants, e.g. while feeding on contaminated grass. Subsequently, the infectious larvae (fins) develop, and reach the definitive hosts via ingestion of contaminated intermediate hosts.
Humans are an accidental host for both species. However, they can become infected, with alveolar (E. multilocularis) or cystic (E. granulosus) echinococcosis by oral uptake of parasite eggs via contact with faeces of infected definitive hosts. The resulting symptoms differ depending on the developmental cycle of the larvae in the human body.
Echinococcosis symptoms
Alveolar echinococcosis, caused by E. multilocularis, almost exclusively affects the liver. The larvae of the parasite produce many small vesicles (alveoli) that penetrate the tissue of the affected organ over the years, similar to the infiltrative growth of a malignant tumour. It most commonly affects people between 50 and 60 years of age or immunocompromised persons are affected, very rarely children or adolescents.
In cystic echinococcosis, caused by infection with E. granulosus, the larvae of the parasite are released in the human intestine. Via the portal vein, they reach the liver, and subsequently other organs such as the lungs. Liquid-filled cysts form, mainly in the liver, but also in other organs and grow, displacing the adjacent tissue in the long term. Cystic echinococcosis occurs in all age groups.
In humans, both diseases remain asymptomatic for many years, before they manifest with jaundice (cholestatic icterus), abdominal pain, fatigue, weight loss or liver enlargement (hepatomegaly). If left untreated, they can be fatal.
Diagnostics
Echinococcosis is mainly diagnosed by means of imaging techniques, which make the cysts visible. The diagnosis is confirmed by serological tests, which detect the antibodies against the parasites in the serum of the patient. EUROIMMUN’s Anti-Echinococcus ELISA (IgG), for instance, is a sensitive antibody screening test for the detection of antibodies against both E. multilocularis and E. granulosus.
Due to different disease courses and treatments, differentiation of cystic and alveolar echinococcosis is indispensable. The increasing overlap in the geographic spread of both parasites has also led to an increased demand for species differentiation. Consequently, EI had adapted its established immunoblot for X to the new IVDR requirements and has put it on the market as the first immunoblot for differentiation of IgG antibodies against E. multilocularis and E. granulosus, adapted to the new IVDR requirements, as the first immunoblot for echinococcosis diagnostics under the new regulation. During the revalidation, the new EUROLINE-Westernblot Anti-Echinococcus (IgG) has even been further improved. The number of specific individual antigen bands was reduced by one in order to provide easier result interpretation.
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