Serology describes a profile of declining malaria transmission in Farafenni, The Gambia.
BACKGROUND
Malaria morbidity and mortality has declined in recent years in a number of settings. The ability to describe changes in malaria transmission associated with these declines is important in terms of assessing the potential effects of control interventions, and for monitoring and evaluation purposes.


METHODS
Data from five cross-sectional surveys conducted in Farafenni and surrounding villages on the north bank of River Gambia between 1988 and 2011 were compiled. Antibody responses to MSP-119 were measured in samples from all surveys, data were normalized and expressed as seroprevalence and seroconversion rates (SCR) using different mathematical models.


RESULTS
Results showed declines in serological metrics with seroprevalence in children aged one to 5 years dropping from 19 % (95 % CI 15-23 %) in 1988 to 1 % (0-2 %) in 2011 (p value for trend in proportions < 0.001) and the SCR dropping from 0.069 year(-1) (0.059-0.080) to 0.022 year(-1) (0.017-0.028; p = 0.004). The serological data were consistent with previously described drops in both parasite prevalence in children aged 1-5 years (62 %, 57-66 %, in 1988 to 2 %, 0-4 %, in 2011; p < 0.001), and all-cause under five mortality rates (37 per 1000 person-years, 34-41, in 1990 to 17, 15-19, in 2006; p = 0.059).


CONCLUSIONS
This analysis shows accurate reconstruction of historical malaria transmission patterns in the Farafenni area using anti-malarial antibody responses. Demonstrating congruence between serological measures, and conventional clinical and parasitological measures suggests broader utility for serology in monitoring and evaluation of malaria transmission.
Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. lotus.vandenhoogen@lshtm.ac.uk.
Lotus L
LL
van den Hoogen
MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College London, London, W2 1PG, UK. jamie.griffin@imperial.ac.uk.
Jamie T
JT
Griffin
Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. jackie.cook@lshtm.ac.uk.
Jackie
J
Cook
Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. nuno.sepulveda@lshtm.ac.uk.|Centre of Statistics and Applications of University of Lisbon, Faculdade de Ciências Da Universidade de Lisboa, Bloco C6-Piso 4, 1749-1016, Lisbon, Portugal. nuno.sepulveda@lshtm.ac.uk.
Nuno
N
Sepúlveda
Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. patrick.corran@lshtm.ac.uk.
Patrick
P
Corran
Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. david.conway@lsthm.ac.uk.
David J
DJ
Conway
Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. paul.milligan@lshtm.ac.uk.
Paul
P
Milligan
Disease Control and Elimination, Medical Research Council Unit, Fajara, 220, The Gambia. maffara@mrc.gm.
Muna
M
Affara
Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK. stephen.allen@lstmed.ac.uk.
Stephen J
SJ
Allen
Infectious Diseases Programme, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4029, Australia. carla.proietti@qimrberghofer.edu.au.
Carla
C
Proietti
Disease Control and Elimination, Medical Research Council Unit, Fajara, 220, The Gambia. sjceesay@mrc.gm.
Serign J
SJ
Ceesay
Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. geoff.targett@lshtm.ac.uk.
Geoffrey A
GA
Targett
Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. umberto.dalessandro@lshtm.ac.uk.|Disease Control and Elimination, Medical Research Council Unit, Fajara, 220, The Gambia. umberto.dalessandro@lshtm.ac.uk.
Umberto
U
D'Alessandro
Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. brian.greenwood@lshtm.ac.uk.
Brian
B
Greenwood
Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. eleanor.riley@lshtm.ac.uk.
Eleanor M
EM
Riley
Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. chris.drakeley@lshtm.ac.uk.
Chris
C
Drakeley
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000913:Antibodies, Protozoan / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D005714:Gambia / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008288:Malaria / Q000453:epidemiology*; D008297:Male; D020066:Merozoite Surface Protein 1 / Q000276:immunology; D008875:Middle Aged; D010961:Plasmodium / Q000276:immunology*; D016036:Seroepidemiologic Studies; D055815:Young Adult
D000913:Antibodies, Protozoan; D020066:Merozoite Surface Protein 1