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Echinococcosis 281.e1

Echinococcosis
VetBooks.ir Diseases and Disorders

• Diarrhea (occasionally dogs and cats)
BASIC INFORMATION
• Hydatid cyst disease (primarily intermediate great care should be taken when handling
feces from a dog suspected of harboring adult
Definition hosts such as humans, sheep, and cattle) E. granulosus.
• Cestode (tapeworm) infection with larval ○ Recently, hydatid cyst disease has been
stages (hydatid cysts) that causes hydatid recognized in dogs. Differential Diagnosis
disease (important human disease) Other taeniids, including many tapeworms in
○ Cystic echinococcosis is caused by Echi- HISTORY, CHIEF COMPLAINT the genera Taenia and Multiceps
nococcus granulosus. • Clinical signs of hydatid disease in domes-
○ Alveolar echinococcosis is caused by ticated animals are uncommon; humans are Initial Database
Echinococcus multilocularis. most commonly affected by disease. • Fecal examination may reveal eggs that are
○ Polycystic echinococcosis is caused by Echi- • Intermediate host’s signs are related to identical to other taeniids.
nococcus vogelii or Echinococcus oligarthrus. location and size of cyst and the species of • Among the three genera (Echinococcus, Taenia,
• Hydatid cyst disease refers to the clinical condi- Echinococcus infecting the host. and Multiceps), the eggs of the taeniids are
tion in which intermediate hosts have single • Definitive hosts with adult tapeworms are very similar in their structure. Each egg has a
or multiple, often large, intraparenchymal usually well but may have mild enteritis. centralized portion that demonstrates six tiny
cysts containing brood capsules that contain hooklets. The central portion is surrounded
protoscolices suspended in serous fluid. PHYSICAL EXAM FINDINGS by a striated egg shell.
• When ingested by the canine or feline defini- • Generally unremarkable (dogs, cats) • Latex gloves should be worn when handling
tive host, protoscolices (parasite larvae) usually • Adult tapeworms are small, ranging from suspect feces, and strict observance of lab
develop into adult tapeworms within the host’s 1.2-10 mm in length. They have a limited biosafety is essential.
small intestine, causing minimal (if any) disease. number of proglottids (only 3 or 4), and • All materials related to the fecal flotation
even the gravid (most distal) proglottids are procedure should be autoclaved before
Synonyms very difficult to observe grossly. disposal. Feces should be disposed of with
Hydatid disease, hydatidosis • Respiratory signs, abdominal distention, and similar caution.
other signs of hydatid cyst disease are rare
Epidemiology in dogs or cats because they are definitive Advanced or Confirmatory Testing
SPECIES, AGE, SEX hosts, not intermediate hosts. • Diagnosis in definitive hosts is by coproan-
• E. granulosus: definitive hosts are dogs and tigen or DNA detection.
other canids; intermediate hosts are sheep, Etiology and Pathophysiology • Hydatid cysts at necropsy, with accompany-
goats, swine, cattle, horses, camels, and humans. • E. granulosus adults reside in the small ing histopathologic examination
• E. multilocularis: definitive hosts are foxes intestine of the definitive host (dogs, coyotes,
and, less frequently, dogs, cats, coyotes, and wolves). TREATMENT
wolves; intermediate hosts are small rodents. • Eggs are passed into the feces, where they
• E. vogelii: definitive hosts are bush dogs and are ingested by an intermediate host (e.g., Treatment Overview
dogs; intermediate hosts are rodents. cattle, sheep, horses). Due to the zoonotic nature of this parasite,
• E. oligarthrus: definitive hosts are wild felids; • In the intermediate host, the organism invades appropriate anthelmintic therapy is critical for
rodents are intermediate hosts. the small intestine and spreads through the eliminating the adult cestode.
circulatory system, entering organs of pre-
RISK FACTORS disposition. The organism develops into a Acute General Treatment
Exposure to and ingestion of intermediate thick-walled, unilocular (single compartment) • Adult stages of the parasite may be treated
hosts (rodents, cattle, sheep) harboring the cyst that gradually enlarges. with praziquantel 2.5-7.5 mg/kg PO or SQ
hydatid cysts ○ Typically, liver, lungs, and other organs once.
(central nervous system, bone, heart) are • Hydatids require surgical removal from
CONTAGION AND ZOONOSIS affected. human intermediate hosts. The thick-walled,
• Highly zoonotic • Definitive host becomes infected by ingestion unilocular cysts of E. granulosus are less
• Humans (and other suitable intermediate of raw hydatid cyst in the visceral organs of difficult to remove, but the thin-walled,
hosts) become infected by ingestion of eggs intermediate hosts. multilocular cysts of E. multilocularis are
from the feces of definitive hosts. • E. multilocularis larval growth remains in quite invasive and almost impossible to
• After ingestion, the organism spreads, and the proliferative stage, resulting in invasion remove. The organs infected by the hydatid
cysts can develop in various organs. of surrounding tissues. The liver is primarily cyst will also affect the prognosis.
affected, with occasional metastasis to the • Epsiprantel (Cestex): dogs, 5.5 mg/kg PO
GEOGRAPHY AND SEASONALITY brain and lungs. The organism develops into once; cats, 2.75 mg/kg PO once. Single doses
• E. granulosus occurs worldwide; more a thin-walled, multilocular (many compart- eliminate E. multilocularis in over 99% of
frequent in rural, grazing areas ments) cyst that easily spreads, overtaking animals, but there may be residual worm
• E. multilocularis: Northern Hemisphere and the affected organs. burdens in some animals.
northern portions of South America • E. vogelii larvae have a predisposition for
• E. vogelii and E. oligarthrus: Central and the liver. Possible Complications
South America Gastrointestinal adverse effects may be seen
Clinical Presentation DIAGNOSIS with antiparasitics.
DISEASE FORMS/SUBTYPES Diagnostic Overview Recommended Monitoring
• Absence of clinical signs (definitive hosts The main concern is zoonosis. Because this • Regular fecal flotation
such as dogs and cats) is an extremely pathogenic zoonotic parasite, • Use caution when handling feces.

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