Echinococcosis

Human echinococcosis is a zoonotic condition transmitted from animals and caused by Echinococcus tapeworms, presenting as cystic echinococcosis (hydatid disease), alveolar echinococcosis, and neotropical forms ^[1][2][3]. Definitive carnivore hosts harbour mature worms and shed eggs, while humans become intermediate hosts after ingesting eggs ^[1][3].

Both principal forms show prolonged asymptomatic incubation lasting many years before larval growth triggers signs ^[2][3]. Cystic echinococcosis produces fluid-filled cysts chiefly in liver and lungs, yielding abdominal pain, nausea, chronic cough or chest discomfort, with less frequent involvement of other organs ^[2][3]. Alveolar echinococcosis develops a tumour-like hepatic lesion over 5–15 years and may disseminate to spleen, lungs or brain, causing weight loss and malaise ^[2][3]. Lung hydatidosis is usually detected incidentally on chest imaging due to slow cyst growth ^[4].

Worldwide, over one million individuals may be affected by cystic or alveolar echinococcosis, with many experiencing life-threatening syndromes and reduced quality of life ^[1]. Cystic echinococcosis has a worldwide distribution and peaks in pastoral communities, whereas alveolar echinococcosis is confined to the northern hemisphere ^[2]. Neotropical forms are rare and reported only in rural tropical parts of Central and South America ^[2]. Surgical cystic cases show about 2.2% postoperative mortality and 6.5% relapse ^[1].

Human echinococcosis is a zoonotic disease transmitted to humans from animals, caused by tapeworms of the genus Echinococcus ^[1]. Herbivorous and omnivorous animals act as intermediate hosts, becoming infected by ingesting parasite eggs in contaminated food and water, after which the parasite develops into larval stages in the viscera ^[1]. Carnivores act as definitive hosts harbouring the mature tapeworm in their intestine and are infected through consumption of viscera of intermediate hosts containing parasite larvae ^[1]. Periodic deworming of dogs, improved slaughter hygiene with proper destruction of infected offal, and public education have been found to lower and in high-income countries prevent transmission ^[1]. The different Echinococcus species differ in their transmission cycles ^[2].

Cystic echinococcosis is preventable through periodic dog deworming with praziquantel at least four times yearly, hygienic slaughter practices with proper destruction of infected offal, and public education ^[1]. For alveolar echinococcosis, regular deworming of domestic carnivores with wild-rodent access and anthelminthic baiting of wild definitive hosts have reduced prevalence in European and Japanese settings, whereas culling of foxes and stray dogs is inefficient ^[1].

1. 1 World Health Organization. Echinococcosis [Internet]. cited 23 Oct 2026. Available from: https://www.who.int/news-room/fact-sheets/detail/echinococcosis
2. 2 World Health Organization. Echinococcosis [Internet]. cited 23 Oct 2026. Available from: https://www.who.int/news-room/questions-and-answers/item/echinococcosis
3. 3 World Health Organization. Echinococcosis [Internet]. cited 23 Oct 2026. Available from: https://www.who.int/health-topics/echinococcosis
4. 4 Lupia T et al. Pulmonary Echinococcosis or Lung Hydatidosis: A Narrative Review. Surg Infect (Larchmt). 2021 Jun. PMID: 33297827. doi: 10.1089/sur.2020.197. PubMed: https://pubmed.ncbi.nlm.nih.gov/33297827/