Pathophysiology And Epidemiology of Echinococcal Infection: A Review

Abstract

Cystic echinococcosis (CE) is a cosmopolitan zoonosis representing serious health and economic risks to humans and livestock. The disease is commonly an indolent, asymptomatic and chronic infection by hydatid cyst. Causing both human and veterinary medical costs, as well as constituting loss of production in endemic areas. Prophylactic vaccination has been regarded as one of the most effective approaches for reducing echinococcosis. During the last few decades, much effort has been made to find and characterize protective antigens ofEchinococcus granulosus as well as investigating their immunization potential in different animal models. Therefore, the current study was conducted to systematically review and identify the best candidate antigens for vaccine formulation against cystic echinococcosis. Hum Echinococcosis in man is caused by larval stages of Taenia echinococcus—parasites whose adult form occurs in the intestines of dogs, wild canids and other carnivores (definitive hosts). The domestic and wild herbivores are the intermediate stages of life cycle. Humans encounter the parasite as an incidental intermediate host by ingestion of parasite eggs; typically, when consuming food, water or soil contaminated with feces from infected canids. The two most significant species from a medical point of view are E. granulosus, which causes cystic echinococcosis and is globally widespread (primarily in sheep- and cattle-raising areas), and E. multilocularis, which is responsible for alveolar echinococcosis; the latter occurs mainly in the northern hemisphere. Hexacanth embryos, upon ingestion, penetrate the wall of small intestine and reach the portal circulation from where they are carried to liver predominantly. From there, they can migrate to the lungs, brain or other tissues as cystic lesions. The clinical presentation depends primarily on size, number of cysts and the topography. CNS involvement by E. granulosus is uncommon and accounts for approximately 2% of cases. When it does develop, cysts are uniformly well-defined, round(ovoid) and intraparenchymal, often achieving considerable size with resultant mass effect producing neurologic symptoms or compressing surrounding brain structures is not unusual.

Keywords:

Echinococcosis, Echinococcus granulosus, Echinococcus multilocularis

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