title: Indirect Haemagglutination Test in Comparison with ELISA for Detection of Antibodies against Invasive Amoebiasis.
abstract: BACKGROUND
  Diagnosis of amoebiasis is based on combination of tests like microscopy, imaging, serology and molecular methods. In absence of molecular techniques, serology can be used as an alternative aid. Various serological techniques were reported with different sensitivity and specificity. The diagnostic efficiency of these assays mainly depends on the characteristics of antigen that is being used and various conditions of performance.
  
  
  OBJECTIVE
  To evaluate the efficiency of recombinant calcium binding domain containing protein by Indirect Haemagglutination Assay (IHA) against a commercial ELISA among amoebic liver abscess cases and control group.
  
  
  METHODS
  The study was carried out during the period of 2011-2015 and blood samples were collected from suspected amoebiasis cases who were attending the clinics of Medicine and Paediatrics department, JIPMER. A total of 200 sera samples which included 100 Amoebic Liver Abscess (ALA), 50 cases of other parasitic infections and liver diseases and 50 presumed healthy controls were examined by IHA and commercial ELISA. In brief, chick cells were stabilized by Double Aldehyde Sensitization (DAS) method. Optimum Sensitizing Dose (OSD) of the antigen was determined. The test was performed in a U-bottomed microtiter plate with recombinant amoebic antigen (12.5μg/ml), incubated at Room Temperature (RT) for 2 hours. RIDASCREEN Entamoeba IgG ELISA kit which is commercially available was used to evaluate the samples as per manufacturer's instruction.
  
  
  RESULTS
  The overall sensitivity and specificity of the IHA was 62% and 96%, respectively when compared to ELISA having sensitivity and specificity of 69% and 90%, respectively. The positive predictive value of the IHA was 91% while negative predictive value was 79%. Similarly, the positive predictive value of the ELISA was 87% while negative predictive value was 74%.
  
  
  CONCLUSIONS
  As serology heavily suffers due to lack of a standardised test system employing the native antigen, there arises need to identify alternative source of recombinant antigen which could effectively improvise the existing lacunae in the current system. Serology acts as an adjunct in clinical decision making if properly interpreted. This is an important consideration in endemic region where health services resources are limited.
authors.affiliation: Ph.D Scholar, Department of Microbiology, Jawaharlal Institute of Postgraduate Medical Education and Research , Puducherry, Tamil Nadu, India .
authors.forename: Sankaramoorthy
authors.initials: S
authors.lastname: Dhanalakshmi
authors.affiliation: Junior Resident, Department of Microbiology, Jawaharlal Institute of Postgraduate Medical Education and Research , Puducherry, Tamil Nadu, India .
authors.forename: Chidambaram
authors.initials: C
authors.lastname: Meenachi
authors.affiliation: Director and Senior Professor of Microbiology, Jawaharlal Institute of Postgraduate Medical Education and Research , Puducherry, Tamil Nadu, India .
authors.forename: Subhash Chandra
authors.initials: SC
authors.lastname: Parija
keywords: Amoebic Liver Abscess; Double aldehyde sensitized cells; Recombinant antigen; Seroepidemiology