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Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Methodol. Dec 26, 2015; 5(4): 185-195
Published online Dec 26, 2015. doi: 10.5662/wjm.v5.i4.185
Immunodiagnosis of human hydatid disease: Where do we stand?
Bahador Sarkari, Zahra Rezaei
Bahador Sarkari, Basic Sciences in Infectious Diseases Research Center, Shiraz University of Medical Sciences, Shiraz 71345-1735, Iran
Zahra Rezaei, Department of Parasitology and Mycology, School of Medicine, Shiraz University of Medical Sciences, Shiraz 71345-1735, Iran
Author contributions: Sarkari B performed the literature search, wrote the first draft of the manuscript, edited and approved the final version; Rezaei Z performed the literature and approved the final version of the manuscript.
Conflict-of-interest statement: The authors declare that there are no conflicts of interest.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Bahador Sarkari, PhD, Professor of Immunoparasitology, Basic Sciences in Infectious Diseases Research Center, Shiraz University of Medical Sciences, Zand Street, Building No. 3, Shiraz 71345-1735, Iran. sarkarib@sums.ac.ir
Telephone: +98-71-32305291 Fax: +98-71-32305291
Received: August 4, 2015
Peer-review started: August 6, 2015
First decision: September 22, 2015
Revised: October 26, 2015
Accepted: November 13, 2015
Article in press: November 17, 2015
Published online: December 26, 2015
Processing time: 132 Days and 19.4 Hours
Abstract

Cystic echinococcosis (CE) is a zoonotic parasitic infection caused by the larval stage of Echinococcus granulosus. Diagnosis of CE mainly relies on a combination of serological testing along with imaging approaches. A variety of serological methods, mainly based on hydatid cyst fluid, antigen B (AgB) and antigen 5, have been developed and used for immunodiagnosis of CE, yet their performances are not satisfactory. Although utilizing of recombinant or synthetic antigens, improved the performance of serological tests, it has not applicably overcome the problem of low sensitivity and cross reactivity, seen in the diagnosis of CE. Performances of immunodiagnostic tests based on AgB subunits are promising. The 8 kDa subunit of AgB is the most studied antigen in native, synthetic or recombinant form for diagnosis of CE. From the 5 subunits of AgB, antigen B8/1 and B8/2 provided the highest diagnostic sensitivity and specificity. Moreover, detecting of specific antibodies of IgG subclasses has improved the efficacy of immunodiagnostic tests. Among the IgG subclasses, both IgG2 and IgG4 are considered as good markers for diagnosis and IgG4 as a suitable marker for follow up of the patients. In this review an overview of immunodiagnostic methods, related antigens and their performances in the diagnosis of CE are given. The paper highlights pitfall and challenges in the serological diagnosis of CE. Moreover, limitation of currently available immunodiagnostic tests and the most recent development in the designing and application of serological assays for diagnosis of CE in human are addressed.

Keywords: Immunodiagnosis, Cystic echinococcosis, Hydatid cyst

Core tip: Cystic echinococcosis (CE) (hydatid cyst) is one of the most important parasitic diseases, causing tremendous morbidity and mortality for the human patients. Diagnosis of CE mainly relies on ultrasound images of the cyst along with serological testing. So far, there is no highly specific and sensitive immunodiagnostic test for diagnosis of CE and performances of the currently available tests are not satisfactory. Different antigenic sources including hydatid cyst fluid, antigen B and 5, excretory-secretory antigens of larval stage or adult worm have widely been used for development of serological assays for diagnosis of CE. Utilizing of antigen B subunits in immunodiagnostic tests and detection of IgG subclasses, as a good marker, opened a promising perspective in diagnosis of this debilitating disease.