Using Serological Assays Detecting IgG to Estimate Malaria Transmission Intensity in Thies, Senegal 公开
Chavers, Tyler Preston (2017)
Published
Abstract
Malaria is an international public health issue with over 3 billion of the world's population at risk. Heterogeneous patterns of malaria transmission intensity (MTI) across endemic areas require surveillance systems that estimate malaria exposure at all levels of MTI. Serosurveillance using tools such as Luminex® multiplex assays can provide new estimates of transmission intensity by estimating the strength of antibody responses to infection using median fluorescence intensity (MFI). This study aimed to estimate MTI in the population of Thies, Senegal using a Luminex multiplex assay measuring changes in MFI as surrogates for IgG antibody levels across a longitudinal cohort design. Demographic information and blood spots for IgG multiplex analyses were collected during biannual visits from 2012 to 2015 from a cohort (n = 1,980) in the hypoendemic region of Thies, Senegal. We used these data to calculate novel estimates of MTI, including the annual frequency of seropositives (defined as individuals with MFI values above seropositive cutoffs), the number of annual seropositives with increased MFI values after each transmission season, and to plot individual MFI values for each visit as proxy measures of antibody responses to malaria during the study. There was a 15% increase of seropositives by PfMSP-119 across year 1, -15% in year 2, and -4% in year 3. All other antibody responses displayed a range of -3% to 1% among all species. We identified higher frequencies of seropositives with increases in MFI for Plasmodium falciparum throughout each transmission season, with a total 679 for PfMSP-119, 368 for AMA-1, and 88 for LSA-1 across the duration of the study. Responses to other malarial species occurred at lower levels, with 110 seropositives for PoMSP-119, 50 seropositives for PmMSP-119, and six seropositives for PvMSP-119 across all three transmission seasons. Plotting the MFI levels for five individuals at each cohort visit revealed five dynamic trends of malarial exposure across the study, which may provide alternate measures for malaria transmission. These analyses have identified potential methods for estimating MTI using antibody data with success in an area of low transmission, but require testing in other areas and validation before use in malaria surveillance.
Table of Contents
Chapter 1
Literature Review.. ................................................1
Chapter 2
Methods. ...........................................................20
Chapter 3
Results. .............................................................26
Chapter 4
Discussion.. ........................................................30
Chapter 5
Public Health Implications. ...................................38
Additional Pages
Tables and Figures. .............................................40
References. .......................................................46
Appendices. .......................................................52
Appendix A: Data Organization Figures..........................52 .
Appendix B: Cohort Study Protocol................................54
Appendix C: SAS Code for Data Organization.................59 .
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