Echinococcosis: The parasitic tapeworm that grows silently in your liver for years
Echinococcosis: Silent parasite grows for years—dogs spread tapeworm cysts
Jamila Yusuf spent fifteen years wondering why she always felt tired.
The 42-year-old shepherd from rural Kyrgyzstan attributed her fatigue to hard work—long days tending sheep in mountain pastures, caring for her four children, managing the household. When her abdomen began to swell, she assumed she was simply gaining weight.
By the time abdominal pain became unbearable and she finally made the difficult journey to a regional hospital, the ultrasound revealed something shocking: a massive cyst in her liver, nearly 15 centimeters across. Inside that cyst lived the larval stage of a parasitic tapeworm that had been growing inside her for over a decade.
“The doctor showed me the ultrasound image,” Jamila recalled. “I couldn’t believe something that big was inside me. He asked if I worked with dogs. Of course I did—we had three sheepdogs. He explained the dogs carried parasites from eating infected sheep organs, and I’d probably swallowed the parasite eggs years ago from contaminated food or water.”
Jamila’s condition is called echinococcosis—a parasitic disease that occurs in two main forms in humans and can grow silently for years before symptoms appear. It’s a neglected tropical disease that most people have never heard of, yet it affects hundreds of thousands worldwide, particularly in pastoral communities where people live and work closely with dogs and livestock.
Understanding the Silent Invader
Echinococcosis is caused by tapeworms from the genus Echinococcus. The two main forms affecting humans are cystic echinococcosis (also called hydatidosis or hydatid disease) caused by Echinococcus granulosus, and alveolar echinococcosis caused by Echinococcus multilocularis.
The parasites have a complex life cycle involving two hosts. Dogs, foxes, and other carnivores harbor the adult worms in their intestines and evacuate parasite eggs in their feces. A single dog can pass millions of microscopic eggs.
When livestock animals like sheep, goats, cattle, or pigs ingest contaminated grass or water, the eggs hatch in their intestines and the larvae travel through the bloodstream to organs—mainly the liver and lungs—where they develop into cysts filled with more larvae.
The cycle completes when dogs eat the organs of infected livestock during slaughter or from dead animals, ingesting the cysts and becoming infected with adult tapeworms.
Humans are accidental hosts. We get caught in the middle of this cycle when we accidentally swallow parasite eggs—from petting contaminated dog fur, eating unwashed vegetables grown in contaminated soil, or drinking contaminated water.
According to WHO’s Q&A on echinococcosis, once eggs are ingested, they develop into larvae in several organs, mainly the liver and lungs. But unlike in livestock, the parasites can’t complete their life cycle in humans—we’re a dead-end host. The larvae just keep growing.
For more on parasitic diseases transmitted from animals, see our article on zoonotic diseases and human health.
Two Forms, Both Devastating
Cystic echinococcosis is the more common form. The disease is characterized by an asymptomatic incubation period that can last many years—sometimes decades—until the parasite cysts evolve and grow large enough to trigger clinical signs.
The larval stages develop as one or more cysts mainly in the liver (in about 70% of cases) and lungs (20% of cases), and less frequently in the bones, kidneys, spleen, muscles, central nervous system, and eyes.
When cysts invade the liver, symptoms commonly include abdominal pain, nausea, and vomiting. If the lung is affected, clinical signs include chronic cough, chest pain, and shortness of breath. The cysts can grow very large—some reach the size of a grapefruit or even larger, containing liters of fluid.
Alveolar echinococcosis is less common but far more dangerous. It’s characterized by an asymptomatic incubation period of 5 to 15 years and the slow development of a primary tumor-like lesion which is usually located in the liver.
Unlike cystic echinococcosis, where the parasite forms a contained cyst, alveolar echinococcosis grows like a cancer, infiltrating surrounding liver tissue. Lesions may involve other organs such as the spleen, lungs, and brain following dissemination of the parasite via the blood and lymphatic system.
Clinical signs include weight loss, abdominal pain, general malaise, and signs of hepatic failure. If left untreated, alveolar echinococcosis is progressive and fatal—it has been called “parasitic cancer” because of its invasive growth pattern and poor prognosis without treatment.
Dr. Francesca Tamarozzi, an infectious disease specialist who has worked extensively with echinococcosis patients in Central Asia, explained the cruel nature of the disease: “By the time people develop symptoms, the parasite has often been growing for many years. The liver cyst might be so large that surgery becomes extremely complicated. In alveolar echinococcosis, the tumor-like lesion might already be inoperable. Early detection is critical, but how do you screen for a disease that causes no symptoms?”
Diagnosis and Treatment Challenges
Human cystic echinococcosis is diagnosed with imaging tools such as ultrasound or computed tomography, and laboratory confirmation relies on serological tests that detect antibodies to the parasite.
WHO has been harnessing ultrasound capacity for early detection, published as a feature story in October 2023, as portable ultrasound machines can be used for mass screening in endemic areas.
Diagnosis of alveolar echinococcosis is based on clinical findings and epidemiological data, imaging techniques, histopathology and/or nucleic acid detection, and serology.
Treatment is expensive and complicated, sometimes requiring extensive surgery and prolonged drug therapy.
In June 2025, WHO published new guidelines for the treatment of patients with cystic echinococcosis, providing evidence-based guidance on treatment choices so patients can be offered appropriate care.
The treatment approach should be decided based on results from ultrasound images of the cyst. Options include:
PAIR technique (Puncture, Aspiration, Injection, Re-aspiration)—a minimally invasive procedure where a needle is inserted into the cyst under ultrasound guidance, the fluid is aspirated, a chemical is injected to kill the parasites, then the fluid is aspirated again.
Surgery to remove the entire cyst—this is often necessary for large cysts or cysts in critical locations. Surgery can be complex and risky, particularly when cysts are in the brain or near major blood vessels.
Anti-infective drug treatments—typically albendazole, sometimes for many months or even years. The drugs can kill larvae and prevent cyst growth, but they work slowly.
Watch and wait—for small, inactive cysts that aren’t causing symptoms, careful monitoring may be appropriate.
For alveolar echinococcosis, early diagnosis and radical surgery followed by anti-infective prophylaxis remain the key elements. If the lesion is confined, radical surgery offers the possibility of cure. Unfortunately, in many patients the disease is diagnosed at an advanced stage, and palliative surgery, if carried out without or with incomplete anti-parasitic treatment, frequently results in relapses.
Jamila, the Kyrgyz shepherd, underwent surgery to remove the large cyst from her liver, followed by months of anti-parasitic medication. “The surgery was terrifying,” she said. “The doctors had to remove part of my liver along with the cyst. Recovery took months. I couldn’t work. My family struggled financially. All because of a parasite I couldn’t even see.”
A Disease of Poverty and Pastoralism
Echinococcosis is classified as a neglected tropical disease, though it occurs in temperate and even cold climates as well. It’s primarily a disease of poverty and pastoralism, affecting communities that depend on livestock for their livelihoods and live in close contact with dogs.
Endemic areas include parts of Central Asia, China, the Mediterranean region, South America, and East Africa. A study from Kyrgyzstan in April 2020 showed the importance of high-resolution data in exploring within-country variations.
Mongolia has made significant progress in control efforts, documented in a June 2020 update.
The Islamic Republic of Iran has been tackling dog-related zoonoses, as described in a June 2022 feature story, with growing momentum to prevent and control cystic echinococcosis.
WHO’s work on strengthening echinococcosis prevention and control includes improving surveillance data, working with veterinary and food safety authorities, and building capacity for early diagnosis and clinical management.
Prevention Is Possible
The good news: echinococcosis is preventable.
Prevention strategies include:
Regular deworming of dogs with praziquantel medication, particularly in endemic areas. Dogs should be treated every 4-6 weeks in high-risk communities.
Preventing dogs from eating infected livestock organs. This means proper disposal of animal carcasses and offal, not feeding raw organs to dogs, and controlling stray dog populations.
Improving slaughter practices to prevent dogs from accessing infected animal organs. Proper meat inspection can identify infected livestock.
Health education about the disease, transmission routes, and prevention measures. Communities need to understand the risks of close contact with dogs and the importance of hand hygiene.
Vaccination of livestock. An effective vaccine for sheep exists (EG95), and WHO has been increasing the adoption of animal vaccines as documented in an April 2019 update, to address livestock losses and boost control of neglected zoonotic diseases.
Access to clean water and sanitation to reduce environmental contamination with parasite eggs.
In November 2025, WHO issued a call for Target Product Profiles for cystic echinococcosis to identify needed innovations in diagnosis and treatment.
Dr. Abdelbaset Bahnasawy, a veterinary public health specialist working in pastoral communities, emphasized the One Health approach: “You can’t control echinococcosis by treating human cases alone. You need to break the transmission cycle, which means veterinary interventions, environmental sanitation, behavior change, and human health services all working together.”
The Road to 2030
Echinococcosis is included in WHO’s Road to 2030 for neglected tropical diseases, published in July 2022, which addresses the burden of disease and death imposed by NTDs.
WHO’s Neglected Tropical Diseases team coordinates global efforts, and pharmaceutical companies like GSK have reaffirmed commitments and expanded donation programmes, as announced in June 2022, to three diseases including echinococcosis support.
A recent European systematic review from June 2025 on incidences and trends of alveolar echinococcosis found the disease is under-reported despite being notifiable in most European countries, highlighting the need for improved surveillance.
WHO maintains a global distribution map of alveolar and cystic echinococcosis to help countries target interventions.
Jamila eventually recovered from her surgery, though she lives with reduced liver function. She now works as a community health educator in her village, teaching others about echinococcosis prevention. “I tell people to deworm their dogs regularly, to wash their hands after petting dogs, to wash vegetables thoroughly,” she explained. “Some people think I’m overreacting—they say they’ve lived with dogs their whole lives with no problems. I show them my surgical scar and tell them about the years I spent with a parasite growing inside me. That usually gets their attention.”
With improved diagnostics, new treatment guidelines, veterinary interventions, and community education, echinococcosis can be controlled. But it requires sustained commitment, adequate resources, and recognition that this neglected disease deserves the same attention as more well-known parasitic infections.
Frequently Asked Questions (FAQs)
Echinococcosis is a parasitic disease that occurs in two main forms in humans: cystic echinococcosis (also known as hydatidosis) caused by the tapeworm Echinococcus granulosus, and alveolar echinococcosis caused by Echinococcus multilocularis. According to WHO, dogs, foxes and other carnivores harbor adult worms in their intestines and evacuate parasite eggs in their feces. If these microscopic eggs are ingested by humans—through petting contaminated dog fur, eating unwashed vegetables, or drinking contaminated water—they develop into larvae in several organs, mainly the liver and lungs. Both forms are characterized by asymptomatic incubation periods lasting many years (5-15 years for alveolar form) until parasite larvae evolve and trigger clinical signs. The disease can cause serious morbidity and death if left untreated. Endemic areas include Central Asia, China, Mediterranean region, South America, and East Africa. See WHO’s global distribution map.
Cystic echinococcosis has an asymptomatic incubation period lasting many years until cysts grow large enough to cause symptoms. Larval stages develop as one or more cysts mainly in the liver (70% of cases) and lungs (20%), less frequently in bones, kidneys, spleen, muscles, central nervous system, and eyes. When cysts invade the liver, common symptoms include abdominal pain, nausea, and vomiting. If lungs are affected, clinical signs include chronic cough, chest pain, and shortness of breath. Alveolar echinococcosis has a 5-15 year incubation period and develops as a primary tumor-like lesion usually in the liver. According to WHO, lesions may involve spleen, lungs, and brain following dissemination via blood and lymphatic system. Clinical signs include weight loss, abdominal pain, general malaise, and signs of hepatic failure. If left untreated, alveolar echinococcosis is progressive and fatal. Early detection is critical—WHO published a feature story in October 2023 on harnessing ultrasound capacity for early detection.
Human cystic echinococcosis is diagnosed with imaging tools such as ultrasound or computed tomography (CT), with laboratory confirmation through serological tests. Alveolar echinococcosis diagnosis is based on clinical findings and epidemiological data, imaging techniques, histopathology and/or nucleic acid detection, and serology. Both forms can be expensive and complicated to treat. WHO’s June 2025 treatment guidelines provide evidence-based guidance on treatment choices based on ultrasound images of cysts. Treatment options include: PAIR technique (Puncture, Aspiration, Injection, Re-aspiration) for minimally invasive treatment, surgery to remove cysts (complex for large or critically located cysts), anti-infective drug treatments (typically albendazole for months or years), or watching and waiting for small inactive cysts. For alveolar echinococcosis, early diagnosis and radical surgery followed by anti-infective prophylaxis are key. If lesions are confined, radical surgery offers cure. Advanced-stage disease diagnosed late often requires palliative surgery, and incomplete anti-parasitic treatment frequently results in relapses. See WHO Q&A.
Echinococcosis is preventable through multiple strategies. Regular deworming of dogs with praziquantel medication every 4-6 weeks is essential in endemic areas. Preventing dogs from eating infected livestock organs requires proper disposal of animal carcasses and offal, not feeding raw organs to dogs, and controlling stray dog populations. Improved slaughter practices and meat inspection identify infected livestock. Health education about transmission routes and prevention measures helps communities understand risks of close contact with dogs and importance of hand hygiene. An effective livestock vaccine (EG95) for sheep exists—WHO has been increasing adoption of animal vaccines as documented in April 2019 to address livestock losses and boost control. Access to clean water and sanitation reduces environmental contamination. WHO works on strengthening prevention and control, improving surveillance data, working with veterinary authorities, and building clinical capacity.
WHO includes echinococcosis in the Road to 2030 for neglected tropical diseases published July 2022. The Neglected Tropical Diseases team coordinates global efforts including strengthening prevention and control programs, improving surveillance data, working with veterinary and food safety authorities, and building capacity for early diagnosis and clinical management. WHO published new treatment guidelines in June 2025 and issued a call for Target Product Profiles in November 2025 to identify needed innovations. WHO maintains global distribution maps and supports country programs—Mongolia made significant progress (June 2020 update), Iran is tackling dog-related zoonoses (June 2022), and a Kyrgyzstan study (April 2020) showed importance of high-resolution data. Pharmaceutical companies like GSK have expanded donation programmes (June 2022) supporting echinococcosis control efforts.
- WHO Echinococcosis Health Topic
- WHO Echinococcosis Fact Sheet
- WHO Echinococcosis Q&A
- WHO Treatment Guidelines for Cystic Echinococcosis (June 2025)
- Global Distribution Map of Echinococcosis
- Harnessing Ultrasound Capacity for Early Detection (Oct 2023)
- Tackling Echinococcosis in Iran (June 2022)
Disclaimer: This article is an adaptation of publicly available information from WHO’s Echinococcosis
health topic page (WHO, Geneva. Licence: CC BYNC-SA 3.0 IGO). WHO is not responsible for the
content or accuracy of this adaptation. This content is for informational and educational purposes
only and does not constitute medical advice. ObserverVoice.com is a news and information platform
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