Publications

This publication reports the proceedings of the preliminary meeting of the working party that met at Gastro 2009 during the World Congress in London. The purpose of the preliminary meeting was to consider the areas that require attention, to discuss some of the findings that have already been published and to agree on the way forward. Our reason for publishing these proceedings is to stimulate interest in this venture and to provide the opportunity for input from the endoscopy community worldwide. The next meeting of the working party will be at the JGES Society meeting in Aomori in April 2011 when we hope to prepare a preliminary classification. This will be presented for general discussion and debate at the International Congress of Endoscopy (ICE) in Los Angeles in September 2011.

BACKGROUND

Associations between antibody responses to Plasmodium falciparum antigens and protection against symptomatic malaria have been difficult to ascertain, in part because antibodies are potential markers of both exposure to P. falciparum and protection against disease.

METHODS

We measured IgG responses to P. falciparum circumsporozoite protein, liver-stage antigen 1, apical-membrane antigen 1 (AMA-1), and merozoite surface proteins (MSP) 1 and 3, in children in Kampala, Uganda, and measured incidence of malaria before and after antibody measurement.

RESULTS

Stronger responses to all 5 antigens were associated with an increased risk of clinical malaria (P < .01) because of confounding with prior exposure to P. falciparum. However, with use of another assessment, risk of clinical malaria once parasitemic, stronger responses to AMA-1, MSP-1, and MSP-3 were associated with protection (odds ratios, 0.34, 0.36, and 0.31, respectively, per 10-fold increase; P < .01). Analyses assessing antibodies in combination suggested that any protective effect of antibodies was overestimated by associations between individual responses and protection.

CONCLUSIONS

Using the risk of symptomatic malaria once parasitemic as an outcome may improve detection of associations between immune responses and protection from disease. Immunoepidemiology studies designed to detect mechanisms of immune protection should integrate prior exposure into the analysis and evaluate multiple immune responses.