Echinococcus Granulosus, Hydatid Disease, Hydatid Cyst

This test is done to diagnose a parasitic disease caused by Echinococcus granulosus.

The genus echinococcus contains the smallest tapeworm in the Taeniidae.
1. The adult worm measures 0.6 cm or less in length.
This is found in areas where there are sheep (herbivorous).
These are in close contact with the dogs and other canines.
1. Other areas are where canines and humans have close contact.

E. granulosus is a parasitic disease caused by a tapeworm of the genus Echinococcus.
This is also called Hydatid cyst disease and Hydatid cyst.
The adult worm is 0.6 cms (3 to 8mm) or less in length.
1. It consists of:
  1. Scolex.
  2. Neck.
  3. 3 proglottids (the segment containing sex organs) which are:
    1. One anterior-most is immature.
    2. One is middle and is mature.
    3. One is terminal and is gravid.

Adult Echinococcus structure

E. granulosus require two mammalian hosts (animal-like dogs, sheep, horses, goat, pigs, and cattle) for completion of their life cycle.
1. It uses dogs or other canines as a definitive host.
  1. The dogs are the definitive host.
  2. Habitat is a small intestine.
2. Herbivorous is an intermediate host, becomes infected by eating the contaminated herbage.

Hydatid cyst host dogs and sheeps

Hydatid cyst life cycle in the intermediate host

Echinococcus life cycle and host

Segments containing eggs (gravid proglottids) or free eggs are passed in the feces of the definitive host, a carnivore.
The eggs are ingested by an intermediate host (maybe humans), in which the metacestode stage and protoscoleces develop.

Hydatid cyst life cycle

Then the cycle is completed if the metacestode and protoscoleces are eaten by a suitable carnivore.
Hydatid cyst (Hydatidosis) develops in various organs like the liver and lungs are the most common site but it can be seen on any other site even these cysts are reported in the eye, brain, kidney, spleen, muscles, and bones.
Hydatid cyst in the early stages is out of the laminated thick membrane, and line by thin germinal epithelium, its size, in the beginning, is 1 cm in diameter.
1. In the end, the older hydatid cyst contains free protoscolices, daughter cyst, an amorphous material, and all these are called hydatid sand.

Hydatid cyst development

Hydatid cyst structure

This disease is present throughout the world.
Children have higher chances to get an infection due to poor hygienic habits.
Human infection occurs accidentally by the feces of infected dogs or other herbivorous.

This depends upon the size and location of the hydatid cyst.
The patients are asymptomatic and the incubation period may be in years when the cyst appears and is clinically diagnosed.
There are nonspecific symptoms of:
1. Nausea.
2. Weight loss.
3. Weakness.
Other symptoms are due to the pressure of these cysts.
In the case of the liver cyst:
1. The patient may have abdominal pain.
2. Nausea, and vomiting.
3. There may be obstructive jaundice.
In the case of the lung:
1. There will be a chronic cough.
2. Chest pain and shortness of breath.
Rupture of the cyst naturally or by taking the sample may lead to anaphylactic shock.
Summary of signs and symptoms:
1. Asymptomatic infection.
2. Hepatomegaly.
3. Cough.
4. Pressure on different organs.
5. Rupture of the cyst may cause allergic reactions like anaphylactic reaction.

Microscopy of hydatid cyst fluid to see scolices, daughter cyst, brood capsules, or hydatid sand.
A complete blood picture may show eosinophilia.
Haemagglutination test with significant titer above 1:100.
1. This is more specific than the traditional Casoni’s test.
Direct microscopic examination for ova and parasite.
Bone marrow biopsy.
CT scan or ultrasonography to find a hydatid cyst.

Surgical removal of the operable cyst. This is the best choice of treatment.
In the case of inoperable cases can give:
1. Mebendazole.
2. Albendazole.
3. Praziquantel.