September 3, 2026 Author : Saraiva da Cunha (infectious diseases ) Echinococcosis is a parasitic zoonotic disease caused by tapeworms of the genus Echinococcus . Human disease has several forms, and the most important are caused by the larval stages of two parasite species: Echinococcus granulosus , which causes the cystic form; Echinococcus multilocularis , which causes the alveolar form. The cystic form, also known as cystic echinococcosis or hydatid disease , is the most common. The cysts that develop in the affected organs, mainly the liver and lungs, are called hydatid cysts and are the principal manifestation of hydatid disease. In Portugal, echinococcosis is a notifiable disease, and diagnosed cases must therefore be reported to the health authorities for epidemiological surveillance and disease control purposes. Transmission of Echinococcosis The life cycle of Echinococcus mainly involves carnivores, which are definitive hosts, and herbivores and omnivores, which are intermediate hosts. The adult parasite lives in the intestine of carnivores, such as dogs and foxes, which shed eggs in their feces that may contaminate soil, water and food. When these eggs are ingested, for example by sheep, goats, cattle or pigs, they hatch in the intestine, the larvae penetrate the intestinal wall and migrate to organs, mainly the liver and lungs, where they form cysts. The parasite's life cycle is completed when carnivores consume raw viscera containing cysts from these animals. Humans are not part of the natural life cycle of Echinococcus ; they are accidental hosts, they develop the disease, but do not transmit it to other people or perpetuate the parasite life cycle . Close contact with species involved in the life cycle, particularly when associated with poor hygiene conditions and lack of disease control in animals, favors infection. I nfection occurs through ingestion of microscopic parasite eggs shed in the feces of infected dogs and other carnivores, which may contaminate hands, water, food, or other objects and surfaces in the environment. For example, infected dogs may also spread eggs onto their fur when grooming themselves, which can subsequently become a source of infection. In the human intestine, the eggs hatch and the larvae penetrate the intestinal wall, enter the bloodstream and reach other organs. Symptoms and diagnosis Cystic echinococcosis or hydatid disease Infection with Echinococcus granulosus leads, in most cases, to the very slow growth of one or more hydatid cysts in organs , mainly the liver and lungs. Many years, even decades, may pass between infection and sufficient growth of cysts to cause symptoms, such as abdominal pain, jaundice, nausea and vomiting in the case of liver cysts, or cough, chest pain and breathing difficulties in the case of lung cysts. In addition to symptoms related to the location of the cysts and their impact on surrounding tissues, hydatid disease may also cause loss of appetite, weight loss and general debility. Diagnosis is based mainly on imaging studies (ultrasound, computed tomography and magnetic resonance image), and laboratory tests may also be performed to detect antibodies against the parasite. In many cases, the diagnosis is incidental, during medical examinations carried out for other reasons . The disease is considered potentially serious, for example if a cyst ruptures or becomes secondarily infected, but it is curable in countries with easy access to medical care. Alveolar echinococcosis Alveolar echinococcosis is less common, but it is the most severe form of the disease. Infection with Echinococcus multilocularis also has a prolonged incubation period, ranging from 5 to 15 years. It is characterized by the slow and invasive growth of a tumor-like lesion, usually in the liver, causing symptoms such as weight loss, abdominal pain, general malaise and signs of hepatic failure, and it may invade other organs and tissues. Treatment of echinococcosis Echinococcosis is a disease requiring treatment that is often expensive, complex and prolonged . In the case of hydatid disease, treatment may include surgery, cyst puncture and aspiration, and antiparasitic medication. Mortality associated with this form of the disease is low in countries with access to diagnosis and treatment, and it is now considered a potentially serious but frequently curable disease. As for alveolar echinococcosis, early diagnosis is essential to control the lesion through surgery. When left untreated, more than 90% of patients may die within 10 to 15 years after diagnosis. Prevention of echinococcosis Prevention of echinococcosis is based on measures that interrupt the parasite life cycle and prevent human contact with its eggs. The main measures are: Deworm dogs regularly , according to the veterinarian recommendations. Do not feed dogs or other carnivores raw viscera and, particularly in farming areas, prevent them from accessing the carcasses of other animals. Do not consume meat or other foods of animal origin that have not undergone veterinary sanitary inspection procedures . Wash hands regularly and always before eating and after handling animals, soil, or environments that may be contaminated. Maintain appropriate hygiene practices when in contact with dogs , for example by not allowing them to lick your face. Thoroughly wash all fruit and vegetables consumed raw. Do not drink untreated water or water from unknown sources . Some facts and figures Human echinococcosis is more common in rural areas associated with livestock farming and grazing . The cystic form occurs worldwide except in Antarctica, whereas alveolar echinococcosis is found only in the Northern Hemisphere. The World Health Organization considers echinococcosis a neglected tropical disease and estimates that more than one million people are infected worldwide. In Europe, cases are relatively rare, but they continue to occur, especially in Mediterranean countries and in Central and Eastern Europe (the Balkans are currently considered the disease epicentre). Between 2010 and 2024, approximately 800-900 cases of echinococcosis were reported annually in the European Union. During the pandemic years, the number of reported cases decreased, and in 2024 the highest figure was recorded: 984 cases, of which 478 were caused by Echinococcus granulosus and 282 by Echinococcus multilocularis . In the same year, the disease resulted in 193 hospitalizations and 3 deaths. In Portugal, the disease is uncommon and its incidence has been declining, although it continues to be diagnosed occasionally . In 2024, four cases and one hospitalization were reported. Between 1997 and 2021, a total of 502 cases were recorded, an average of 20 cases per year. Particular attention should be paid to immigrants from countries where the disease has a high prevalence. In addition to its impact on human health, echinococcosis causes significant economic losses for livestock producers. Echinococcosis therefore remains a public health and animal health concern and can be prevented through simple hygiene measures , animal control and interruption of the parasite transmission cycle. Sources Direção Geral de Alimentação e Veterinária. Equinococosse / hidatidose . European Center for Disease Prevention and Control. Echinococcosis . European Center for Disease Prevention and Control. Surveillance Atlas of Infectious Diseases . World Health Organization. Echinococcosis . Meet the infectious diseases clinical team from Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item. English translation generated with AI and reviewed by the editorial team.
