![]() vogeli is the bush dog ( Speothos venaticus), and possibly domestic dogs. Many rodents can serve as intermediate hosts, but members of the subfamily Arvicolinae (voles, lemmings, and related rodents) are the most typical. Other canids including domestic dogs, wolves, and raccoon dogs ( Nyctereutes procyonoides) are also competent definitive hosts. multilocularis, foxes, particularly red foxes ( Vulpes vulpes), are the primary definitive host species. Intermediate hosts for zoonotic species/genotypes are usually ungulates, including sheep and goats ( E. Natural intermediate hosts depend on genotype. Cysts are generally similar to those found in cystic echinocccosis but are multi-chambered.Įchinococcus granulosus definitive hosts are wild and domestic canids. The Neotropical agents follow the same life cycle although with differences in hosts, morphology, and cyst structure. Neotropical Echinococcosis ( Echinococcus vogeli, E. oligarthrus) Metastasis or dissemination to other organs (e.g., lungs, brain, heart, bone) may occur if protoscolices are released from cysts, sometimes called “secondary echinococcosis.” Oncospheres are released in the intestine and cysts develop within in the liver. Humans are aberrant intermediate hosts, and become infected by ingesting eggs. After ingestion, the protoscolices evaginate, attach to the intestinal mucosa, and develop into adult stages in 32 to 80 days. The definitive host becomes infected by ingesting the cyst-containing organs of the infected intermediate host. Numerous protoscolices develop within these cysts. The oncosphere develops into a multi-chambered (“multilocular”), thin-walled (alveolar) hydatid cyst that proliferates by successive outward budding. After ingestion by a suitable intermediate host, eggs hatch in the small intestine and releases a six-hooked oncosphere that penetrates the intestinal wall and migrates through the circulatory system into various organs (primarily the liver for E. Gravid proglottids release eggs that are passed in the feces, and are immediately infectious. The adult Echinococcus multilocularis (1.2-4.5 mm long) resides in the small intestine of the definitive host. If cysts rupture, the liberated protoscolices may create secondary cysts in other sites within the body (secondary echinococcosis).Īlveolar Echinococcosis ( Echinococcus multilocularis) ![]() Oncospheres are released in the intestine, and hydatid cysts develop in a variety of organs. In these organs, the oncosphere develops into a thick-walled hydatid cyst that enlarges gradually, producing protoscolices and daughter cysts that fill the cyst interior. After ingestion by a suitable intermediate host, eggs hatch in the small intestine and release six-hooked oncospheres that penetrate the intestinal wall and migrate through the circulatory system into various organs, especially the liver and lungs. The adult Echinococcus granulosus (sensu lato) (2-7 mm long) resides in the small intestine of the definitive host. Life CycleĬystic Echinococcosis ( Echinococcus granulosus sensu lato) Research on the epidemiology and diversity of these genotypes is ongoing, and no consensus has been reached on appropriate nomenclature thus far. canadensis group (usually considered G6, G7, G8, and G10). granulosus sensu stricto (G1–G3 genotypes), E. granulosus sensu lato complex include the “classical” E. The known zoonotic genotypes within the E. granulosus have been identified that differ in their distribution, host range, and some morphological features these are often grouped into separate species in modern literature. oligarthrus causes the extremely rare unicystic form. vogeli causes a polycystic form whereas E. oligarthrus, are associated with “Neotropical echinococcosis” E. multilocularis, causes alveolar echinococcosis, and is becoming increasingly more common. Echinococcus granulosus (sensu lato) causes cystic echinococcosis and is the form most frequently encountered. Human echinococcosis (hydatidosis, or hydatid disease) is caused by the larval stages of cestodes (tapeworms) of the genus Echinococcus.
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