title: Multiple comparisons analysis of serological data from an area of low Plasmodium falciparum transmission.
abstract: BACKGROUND
  As a nation reduces the burden of falciparum malaria, identifying areas of transmission becomes increasingly difficult. Over the past decade, the field of utilizing malaria serological assays to measure exposure has grown rapidly, and a variety of serological methods for data acquisition and analysis of human IgG against falciparum antigens are available. Here, different immunoassays and statistical methods are utilized to analyse samples from a low transmission setting and directly compare the estimates generated.
  
  
  METHODS
  A subset of samples (n = 580) from a 2012 Haitian nationwide malaria survey was employed as sample population of low falciparum endemicity. In addition to the Haitian samples, samples from 247 US residents were used as a reference population of 'true seronegatives'. Data acquisition was performed through standard ELISA and bead-based multiplex assays assaying for IgG antibodies to the Plasmodium falciparum antigens MSP-1p19, MSP-1p42(D), MSP-1p42(F), and AMA-1. Appropriate parametric distributions and seropositivity cutoff values were determined by statistical measures.
  
  
  RESULTS
  Data from both assays showed a strong positive skew, and the lognormal distribution was found to be an appropriate statistical fit to the Haitian and American populations. The American samples served as a good serological true negative population for the multiplex assay, but not for ELISA-based data. Mixture model approaches to determine seronegative and seropositive populations from the Haitian data showed a high degree of distribution overlap-likely due to the historical low falciparum transmission in this nation. Different fittings to the reversible catalytic model resulted depending upon the immunoassay utilized and seropositivity cutoff method employed. Data were also analysed through fitting to penalized B-splines, presenting another possible analytical tool for the analysis of malaria serological data.
  
  
  CONCLUSIONS
  Standardization of serological techniques and analyses may prove difficult as some tools can prove to be more useful depending on the area and parasite in question, making clear interpretation a vital pursuit. The presented analysis in the low-endemic nation of Haiti found malaria-naive US residents to be an appropriate seronegative reference population for the multiplex assay, and this assay providing consistent estimates between MSP-1 and AMA-1 antigens of percent seropositives for this low-endemic population.
authors.affiliation: Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA. erogier@cdc.gov.
authors.forename: Eric
authors.initials: E
authors.lastname: Rogier
authors.affiliation: Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA. fwk2@cdc.gov.
authors.forename: Ryan
authors.initials: R
authors.lastname: Wiegand
authors.affiliation: Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA. dmm3@cdc.gov.
authors.forename: Delynn
authors.initials: D
authors.lastname: Moss
authors.affiliation: Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA. jip8@cdc.gov.
authors.forename: Jeff
authors.initials: J
authors.lastname: Priest
authors.affiliation: Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA. angov@us.army.mil.
authors.forename: Evelina
authors.initials: E
authors.lastname: Angov
authors.affiliation: Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA. sheetij.dutta@na.amedd.army.mil.
authors.forename: Sheetij
authors.initials: S
authors.lastname: Dutta
authors.affiliation: Laboratoire National de Santé Publique (LNSP)/Ministère de la Santé Publique et de la Population (MSPP), Port-au-Prince, Haiti. journeltechn@gmail.com.
authors.forename: Ito
authors.initials: I
authors.lastname: Journel
authors.affiliation: Population Services International/Organisation Haïtienne de Marketing Social pour la Santé, Port-au-Prince, Haiti. sejean@ohmasshaiti.org.
authors.forename: Samuel E
authors.initials: SE
authors.lastname: Jean
authors.affiliation: Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA. igd3@cdc.gov.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Mace
authors.affiliation: Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA. aup6@cdc.gov.
authors.forename: Michelle
authors.initials: M
authors.lastname: Chang
authors.affiliation: Programme National de Contrôle de la Malaria/MSPP, Port-au-Prince, Haiti. tileum@hotmail.com.
authors.forename: Jean Frantz
authors.initials: JF
authors.lastname: Lemoine
authors.affiliation: Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA. vxu0@cdc.gov.
authors.forename: Venkatachalam
authors.initials: V
authors.lastname: Udhayakumar
authors.affiliation: Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA. wzb3@cdc.gov.
authors.forename: John W
authors.initials: JW
authors.lastname: Barnwell
mesh_terms: D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000276:immunology; D003430:Cross-Sectional Studies; D006205:Haiti / Q000453:epidemiology; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D007074:Immunoglobulin G / Q000097:blood; D016778:Malaria, Falciparum / Q000453:epidemiology* / Q000276:immunology*; D010963:Plasmodium falciparum / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007074:Immunoglobulin G