title: Estimating malaria transmission intensity from Plasmodium falciparum serological data using antibody density models.
abstract: BACKGROUND
  Serological data are increasingly being used to monitor malaria transmission intensity and have been demonstrated to be particularly useful in areas of low transmission where traditional measures such as EIR and parasite prevalence are limited. The seroconversion rate (SCR) is usually estimated using catalytic models in which the measured antibody levels are used to categorize individuals as seropositive or seronegative. One limitation of this approach is the requirement to impose a fixed cut-off to distinguish seropositive and negative individuals. Furthermore, the continuous variation in antibody levels is ignored thereby potentially reducing the precision of the estimate.
  
  
  METHODS
  An age-specific density model which mimics antibody acquisition and loss was developed to make full use of the information provided by serological measures of antibody levels. This was fitted to blood-stage antibody density data from 12 villages at varying transmission intensity in Northern Tanzania to estimate the exposure rate as an alternative measure of transmission intensity.
  
  
  RESULTS
  The results show a high correlation between the exposure rate estimates obtained and the estimated SCR obtained from a catalytic model (r = 0.95) and with two derived measures of EIR (r = 0.74 and r = 0.81). Estimates of exposure rate obtained with the density model were also more precise than those derived from catalytic models.
  
  
  CONCLUSIONS
  This approach, if validated across different epidemiological settings, could be a useful alternative framework for quantifying transmission intensity, which makes more complete use of serological data.
authors: Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis and Modelling, Imperial College London, London, UK. emilie.pothin@unibas.ch.|Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland. emilie.pothin@unibas.ch.|University of Basel, Basel, Switzerland. emilie.pothin@unibas.ch.
authors: Emilie
authors: E
authors: Pothin
authors: Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis and Modelling, Imperial College London, London, UK. neil.ferguson@imperial.ac.uk.
authors: Neil M
authors: NM
authors: Ferguson
authors: Department of Immunology, London School of Hygiene and Tropical Medicine, London, UK. Chris.Drakeley@lshtm.ac.uk.
authors: Chris J
authors: CJ
authors: Drakeley
authors: Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis and Modelling, Imperial College London, London, UK. a.ghani@imperial.ac.uk.
authors: Azra C
authors: AC
authors: Ghani
mesh_terms: D000293:Adolescent; D000328:Adult; D000913:Antibodies, Protozoan / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008288:Malaria / Q000453:epidemiology / Q000469:parasitology; D016778:Malaria, Falciparum / Q000453:epidemiology* / Q000469:parasitology*; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D010963:Plasmodium falciparum / Q000502:physiology*; D016036:Seroepidemiologic Studies; D055815:Young Adult
chemical_list: D000913:Antibodies, Protozoan