Analysis of antibody profiles in symptomatic malaria in three sentinel sites of Ivory Coast by using multiplex, fluorescent, magnetic, bead-based serological assay (MAGPIX™).

BACKGROUND: Advances in malaria control have reduced the burden of disease resulting from exposure to parasite infections. The consequences on naturally acquired immunity are unclear. A magnetic bead-based immunoassay (MBA) to assess antibody levels in populations living in endemic areas was previously evaluated. In this study, the effect of clinical attacks on immunity was analysed in three sentinel sites of Ivory Coast. METHODS: Recombinant proteins or peptides derived from liver or blood stage antigens of Plasmodium falciparum (CSP, LSA141, LSA3, SALSA, PF13-DBL1α1, GLURP, AMA1, MSP1p19, MSP4p20), the CSP of Plasmodium malariae and the salivary glands antigen of Anopheles gambiae (gSG6) were covalently linked to a colour-coded microsphere (Luminex™ beads) for the multiplex assay. ELISA was used for whole parasite extract antigen. Blood samples (n = 94) of patients consulting for symptomatic malaria attacks and living in three different malaria endemic settings (rural and periurban) were analysed. RESULTS: Highly variable seroprevalence of antibody responses against parasite antigens was found ranging from 3 (gSG6) to 97% (MSP4p20). A marked prevalence and significantly higher level of antibodies was found in patients from the rural site (Korhogo), those harbouring the lowest level of parasitaemia. The use of whole schizont extract could not discriminate immunity level, contrary to parasite-derived recombinant proteins or peptides. Prevalence of responders to LSA141 and levels of antibodies to PF13 were significantly different between the three settings. Moreover, the post-treatment clearance of parasites was clearly associated with a significantly higher level of antibody response for almost 50% of the parasite antigens tested. CONCLUSION: The multiplex MBA-Magpix technology assay provides an accurate high throughput monitoring of parasite-specific antibodies during symptomatic malaria. The levels of antibody responses may provide a risk criterion with respect to the degree of parasitic infection. Additionally, they can be used as an indicator in the implementation of malaria prevention and local control strategies.

Open-label, randomized, non-inferiority clinical trial of artesunate-amodiaquine versus artemether-lumefantrine fixed-dose combinations in children and adults with uncomplicated falciparum malaria in Côte d'Ivoire.

BACKGROUND: Emergence of artemisinin resistance has raised concerns that the most potent anti-malarial drug may be under threat. Artesunate-amodiaquine (AS-AQ) and artemether-lumefantrine (AL) are, respectively, the first- and second-line treatments for uncomplicated falciparum malaria in Côte d'Ivoire. Constant monitoring by National Malaria Control Programme (NMCP) of drug efficacy is an important tool in establishing rational anti-malarial drug policies in Côte d'Ivoire. METHODS: In an open label, randomized controlled clinical trial, children and adults were randomized to receive AS-AQ or AL. Both drug regimens were given for three days, and follow-up was for 42 days. The primary endpoint was the 42-day cure rate and was defined as proportion of patients with PCR-corrected cure rate after 42 days of follow-up. RESULTS: A total of 383 patients who were attending the Anonkoua-koute (Abidjan), Petit Paris (Korhogo) and Libreville (Man) hospitals and presenting with symptomatic acute uncomplicated falciparum malaria were randomized to receive AS-AQ (188) and AL (195). The intention-to-treat analysis showed effectiveness rates of 94.7% and 96.4% for AS-AQ and AL, respectively on day 42. After adjustment for PCR, these rates were 96.8% and 99%, respectively. At day 42, in per-protocol analysis, Adequate clinical and parasitological response (ACPR) PCR uncorrected was 97.8% and 97.4% for AS-AQ and AL, respectively. The PCR adjusted ACPR was 100% for each combination and both regimens were well tolerated. CONCLUSIONS: This study has shown the high efficacy of AS-AQ in patients of all ages with acute uncomplicated falciparum malaria and AS-AQ was non-inferior to AL. Continuous efficacy monitoring is recommended.