Dr.Arsalan Khan

1. Arsalan Khan
2014-ag-1451
MPhil CMS
Semester 2nd
University of Agriculture, Faisalabad Pakistan
Parasites of Companion Animals PARA-704
Echinococcus granulosus

2. Introduction
 Echinococcus granulosus, also called hydatid worm
belongs to class Cestoda
 It causes cystic echinococcosis in livestock and
humans being intermediate hosts and parasitize the
small intestines of adult canids
 It is a zoonotic disease
 Definitive hosts are carnivorous predators like dogs,
wolves, foxes and lions. While sheep, goat, cattle, pigs
and rodents are intermediate hosts. Birds and
arthropods act as mechanical vectors

3. Classification
 Kingdom : Animalia
 Phylum : Platyhelminthes
 Class : Cestoda
 Sub Class : Eucestoda
 Order : Cyclophyllidea
 Family : Taenidae
 Genus : Echinococcus
 Species : Echinococcus granulosus

4. Morphology
 The adult tapeworm ranges in length from 2 mm to
7 mm and has three proglottids when intact — an
immature proglottid, mature proglottid and a gravid
proglottid.
 It has scolex with four suckers and also has a rostellum
with hooks.
 Echinococcus is triploblastic, anus is absent and it has
no digestive system.
 Its body is covered by tegument and the worm is
divided into a scolex, a short neck, and three to six
proglottids. Its body shape is ribbon-like.

5. Transmission
 Adult E. granulosus release eggs within the intestine
which will be transported out of the body via feces
 When contaminated waste is excreted into the
environment, intermediate host has the potential to
contract the parasite by grazing in contaminated
pasture
 It is transmitted from the intermediate host (sheep) to
the definitive host (dogs) by frequent feeding of offal.
Consuming offal containing Echinococcus
granulosus can lead to infection

6. Life cycle
 The adult is in the small intestines of the definitive
host (dogs)
 Gravid proglottids release eggs that are passed in the
feces
 The intermediate hosts are infected by ingesting eggs,
the egg hatches in the small bowel and releases an
oncosphere
 The oncosphere penetrates the intestinal wall and
moves through the circulatory system to various
organs
 In the organs they develop into cysts and enlarge
gradually

7.  The cysts produce protoscolices and daughter
cysts
 Definitive host eats the infected organs and
becomes infected
 After ingestion, the protoscolices evaginate, attach
to the intestinal mucosa and develop into adult
stages
 In 32-80 days, cycle starts over

9. Pathogenesis
 Ingested eggs from animal hatch in the gut and release
oncospheres
 Oncospheres penetrate the intestinal wall, migrate via the
circulation, and lodge in the liver or lungs or, less
frequently, in the brain, bone, or other organs.
 In tissue , E. granulosus oncospheres develop into cysts,
which grow slowly (usually over many years) into large
fluid-filled lesions—hydatid cysts
 Large cysts may contain >1 L of highly antigenic hydatid
fluid as well as millions of protoscolices
 If a cyst in the liver leaks or ruptures, infection can spread
to the peritoneum.

10. Signs
 Signs depend upon the site of infection
 Liver cysts cause abdominal pain or a palpable mass.
Jaundice may occur if the bile duct is obstructed.
Rupture into the bile duct, peritoneal cavity, or lung
may cause fever, urticaria, or a serious anaphylactic
reaction.
 Pulmonary cysts can cause cough, chest pain, and
hemoptysis.
 Brain and spinal cord; cause epilepsy and blindness

11. Diagnosis
 Diagnosis in the definitive host, the dog, is difficult by
ordinary microscopy as it cannot demarcate
between Taenia and Echinococcus eggs
 Detection of antigens in feces by ELISA is currently the
best available technique
 Other techniques are;
 Imaging
 Serologic testing
 Examination of cyst fluid

12. Echinococcus eggs in feaces

13. Treatment
 Surgical Removal of Hydatid Cysts 90% effective but can be
risky depending on location, size, and advancement of cyst
 It may need chemotherapy to prevent recurrance
 Chemotherapy: Albendazole is preferred treatment
because it penetrates into hyatid cysts. Dosage: 10mg/kg
body weight or 400mg 2x daily for 4 weeks
 Mebendazole Dosage: 40mg/kg body weight 3x daily for 3-
6 months
 Dogs are effectively treated with Praziquental
 PAIR Treatment Puncture, aspiration, injection, respiration
 Inject protoscolicidal substances into the cyst

14. Prevention
 In order to prevent transmission to dogs from
intermediate hosts, dogs can be given anthelminthic
vaccinations
 Clean slaughter and high surveillance of potential
intermediate host during slaughter is key in preventing
the spread this cestode to its definitive host
 Proper disposal of carcass and offal after slaughter to
prevent dogs access to offal from livestock
 Boiling livers and lungs which contain hydatid cysts
for 30 minutes has been proposed as a simple,
efficient and saving way to kill the infectious larvae

15. Terminology
 Hydatid : cyst containing watery fluid.
 Cyst: a tough protective capsule enclosing the larva of a parasitic worm or the
resting stage of an organism.
 Rostella: protruding part at the scolex armed with hooks and used for
attachment with the intestinal wall of the hosts.
 Cestode: tapeworm
 Protoscolex: The juvenille scolex formed from the germinal layer of a hydated
metacestode
 Oncosphere: tapeworm embryo that has six hooks and is the earliest
differentiated stage of a cyclophyllidean tapeworm—called also hexacanth
embryo. OR immature forms of the parasite enclosed in an embryonic
envelope
 Cyst morphology: fluid-filled sphere with germinal membrane proliferating
endogenously to form brood capsules
 Echinococcus species: E. multilocularis, E. equinus, E. oligarthrus.
 Offal means organ meat.

16. THANKS