Echinococcosis and allergy

Abstract

The larval stages of Echinococcus granulosus and E. multilocularis are involved in parasitic diseases in humans: cystic echinococcosis (CE) ("hydatid disease") and alveolar echinococcosis (AE), respectively. Both diseases and parasites have tight links with allergy because of the immunological characteristics that contribute to maintain the larvae in their human host as well as their potential in inducing clinical anaphylactic reactions in some patients. Clinical observations in patients and data obtained from mass screenings in various countries have identified both forms of echinococcosis as "polar diseases," i.e., diseases where immunological background of the patients was related to the clinical presentation and course. In particular, abortive cases (i.e., spontaneous cures) have been found in many subjects in endemic areas. On the other hand, immune suppression was associated with severe disease. AE especially might be considered as an opportunistic infection. Experimental and clinical studies have shown that Th1-related immune response was associated with protection and Th2-related response was associated with parasite growth. Genetic characteristics of the host are related to both occurrence and severity of AE and are associated with the extent of IL-10 secretion, which is a major feature of chronic progressing echinococcosis. Anaphylactic reactions, including urticaria, edema, respiratory symptoms, and anaphylactic shock due to spontaneous or provoked rupture of the parasitic cyst, are well known in CE. Anaphylactic reactions in AE are far less frequent, and have been observed in rare cases at time of metastatic dissemination of the parasitic lesions. Echinococcus-specific IgE is present in most of the patients and associated with severity. Specific histamine release by circulating basophils stimulated with E. granulosus antigens is present in all patients with CE and AE. Echinococcus allergens include (1) AgB 12-kDa subunit, a protease inhibitor and a potent Th2 inducer; (2) Ag5, a serine protease; (3) EA 21, a specific cyclophilin, with a homology with other types of cyclophilins; (4) Eg EF-1 beta/delta an elongation factor, with a homology with Strongyloides stercoralis EF that shares the same IgE epitope. A clinical cross-reaction with Thiomucase, a mucopolysaccharidase used in arthritis treatment, has recently been published. However, despite the potential risk of allergic reactions, the dogma "never puncture a hydatid cyst" is no longer valid. International experience of therapeutic technique of "puncture, aspiration, injection, re-aspiration" of hydatid cysts developed at the beginning of the 1980s has proved to be successful in a variety of selected indications that have been reviewed by WHO recommendations. A better understanding of the immunological background of echinococcosis in humans has led to new therapeutic developments, such as immunomodulation using interferon alpha. Th2-driven immunological response and IL-10-related tolerance state are common characteristics of atopic allergy and echi...

Recent Advances in the Immunology and Serological Diagnosis of Echinococcosis

“…One aspect that is likely to be important in the control of such immunological mechanisms is the influence of CD4+ T-helper lymphocytes as they may impact on treatment of echinococcosis (Vuitton, 2004). As indicated earlier, self-cure is a common feature of CE infection in sheep (Zhang and Zhao, 1992;Cabrera et al, 2003), and it most likely also happens in human populations in hyper-endemic areas as patients with calcified cysts are often reported (Moro et al, 2005;Macpherson et al, 2004).…”

About the role and underlying mechanisms of cofactors in anaphylaxis

“…Components of the 'adaptive immune system' were mostly addressed as mediators of enhanced type I allergy. Structures of pathogens leading to sensitization and IgE production or cross-reactivity with existing IgE could serve as allergens themselves (59)(60)(61). IgE antibodies, but even more important IgM and IgG antibodies, also form soluble multimeric antibodyantigen immune complexes.…”

Demographic and Clinical Characteristics of Patients with Anaphylactic Shock after Surgery for Cystic Echinococcosis

“…Infection can occur when humans eat foods contaminated with canine feces or pet dogs that harbor eggs on their fur and then touch their fingers to their lips. 2 Anaphylaxis, including urticaria, edema, and respiratory symptoms, may occur in persons infected with E. granulosus. Shock may result if fluid from the cyst is released into a host who has developed IgE from previous leakage of fluid.…”

“…Shock may result if fluid from the cyst is released into a host who has developed IgE from previous leakage of fluid. 2 A severe anaphylactic shock response can result from release of fluid from the cyst, either spontaneously or after trauma or surgery. 2 This study was undertaken to attempt to determine the risk factors for anaphylactic shock to minimize the risk for perioperative anaphylaxis.…”