Hydatid Cysts of the Liver
In humans hydatid disease is caused by the larvae of a tapeworm called Echinococcus granulosus. Hydatid disease is a serious and potentially fatal condition, which may remain hidden in the body for many years.
How can humans become infected with this tapeworm?
In humans, hydatid disease is caused by the regular contact with dog feces or dog hair which is infected with the tapeworm eggs, or contaminated vegetables. The eggs may stick to the animal's hair or contaminate the vegetable garden.
The eggs are highly resistant to the environment and can remain alive for months. Human infection cannot be occurred from eating infected offal. Hydatid disease is not contagious and is not passed by person to person contact.
Symptoms of Hydatid Disease in Humans
The symptoms of hydatid disease vary according to which body organs are infected. The most commonly infected organ is the liver, but the brain, kidneys and lungs are sometimes affected.
The slow growing cysts are found in the liver (in 70% of cases), the lungs (in 5-15% of cases) and other organs in the body such as the spleen, brain, heart and kidneys (in 10-20% of cases). The cysts are usually filled with a clear fluid called hydatid fluid and are spherical and usually consist of one compartment.
Symptoms can occur a long time after infection and sometimes many years later, but there may be no symptoms at all. If they occur, symptoms may include:
- Weight loss
- A swollen and bloated abdomen
- A cough - and blood or liquid from a ruptured cyst may be coughed up
- Jaundice - pressure from a growing cyst may obstruct the bile ducts
- Malnutrition - sometimes, a lack of vitamins can be caused in the host by the very high nutrient demand of the growing parasite
If the cysts were to rupture while in the body, during surgical removal of the cysts, or by some kind of trauma to the body, the patient would most likely go into a type of shock called anaphylaxis which leads to high fever, severe itching, hives, swelling (edema) of the lips and eyelids, shortness of breath, wheezing and sneezing. Hydatid disease can be fatal without emergency medical treatment.
How is Hydatid Disease Diagnosed?
Hydatid Disease can be diagnosed by a thorough medical history and physical examination
Treatment of Hydatid Disease
The standard form of treatment is surgical removal of the cysts. Surgical removal is combined with drugs such as albendazole or mebendazole which have to be taken before surgery and for 8 weeks after surgery to clear up any spilled hydatid fluid containing live tapeworm components.
One of the risks is that a hydatid cyst may rupture during surgery and spread tapeworm heads throughout the patient's body.
This risk is reduced by giving high doses of the drug albendazole with the surgery, which helps to destroy any remaining tapeworm heads.
Unfortunately the risk of recurrence of hydatid disease is high and around 30% of patients treated for hydatid disease develop the condition again and need repeat treatment.
If there are cysts present in multiple organs or tissues, or the cysts are in dangerous places in the body, surgery may be too difficult and dangerous and in these cases drugs (Albendazole or Mebendazole) and PAIR (puncture-aspiration-injection-reaspiration) become the only possible treatment.
PAIR is a minimally invasive procedure that uses three steps:
- Puncture and needle aspiration of the cyst
- Injection of a scolicidal solution for 20-30 minutes
- Cyst-re-aspiration and final irrigation
There is currently research into a new treatment called Percutaneous Thermal Ablation (PTA) of the germinal layer in the cyst by means of a radiofrequency ablation device. This form of treatment is still new and requires much more testing before being widely recommended.