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Modelling dynamic change of malaria transmission in holoendemic setting (Dielmo, Senegal) using longitudinal measures of antibody prevalence to Plasmodium falciparum crude schizonts extract

Authors
  • Niass, Oumy1, 2
  • Saint-Pierre, Philippe3
  • Niang, Makhtar1
  • Diop, Fode1
  • Diouf, Babacar1
  • Faye, Michel Matar1
  • Sarr, Fatoumata Diène4
  • Faye, Joseph4
  • Diagne, Nafissatou5
  • Sokhna, Cheikh5
  • Trape, Jean-François5
  • Perraut, Ronald1
  • Tall, Adama4
  • Diongue, Abdou Kâ2
  • Toure Balde, Aïssatou1
  • 1 Institut Pasteur Dakar, Immunology Unit, 36 Avenue Pasteur, Dakar, Senegal , Dakar (Senegal)
  • 2 Université Gaston Berger, Laboratoire d’étude et de Recherche en Statistique et Développement, Saint-Louis, Senegal , Saint-Louis (Senegal)
  • 3 Université Paul Sabatier, Institut Mathématique de Toulouse, Toulouse, France , Toulouse (France)
  • 4 Institut Pasteur Dakar, Epidemiology of Infectious Diseases Unit, 36 Avenue Pasteur, Dakar, Senegal , Dakar (Senegal)
  • 5 Institut de Recherche pour le Développement, Dakar, Senegal , Dakar (Senegal)
Type
Published Article
Journal
Malaria Journal
Publisher
Springer (Biomed Central Ltd.)
Publication Date
Oct 11, 2017
Volume
16
Issue
1
Identifiers
DOI: 10.1186/s12936-017-2052-0
Source
Springer Nature
License
Green

Abstract

BackgroundEvaluation of local Plasmodium falciparum malaria transmission has been investigated previously using the reversible catalytic model based on prevalence of antibody responses to single antigen to estimate seroconversion rates. High correlations were observed between seroconversion rates and entomological inoculation rates (EIR). However, in this model, the effects of malaria control interventions and clinical episodes on serological measurements were not assessed. This study monitors the use of antibody responses to P. falciparum crude extracts for assessing malaria transmission, compares seroconversion rates estimated from longitudinal data to those derived from cross-sectional surveys and investigates the effects of malaria control interventions on these measures in an area of declining malaria transmission. In addition, the validity of this model was evaluated by comparison with the alternative model.MethodsFive cross-sectional surveys were carried out at the end of the wet season in Dielmo, a malaria-endemic Senegalese rural area in 2000, 2002, 2008, 2010 and 2012. Antibodies against schizonts crude extract of a local P. falciparum strain adapted to culture (Pf 07/03) were measured by ELISA. Age-specific seroprevalence model was used both for cross-sectional surveys and longitudinal data (combined data of all surveys).ResultsA total of 1504 plasma samples obtained through several years follow-up of 350 subjects was used in this study. Seroconversion rates based on P. falciparum schizonts crude extract were estimated for each cross-sectional survey and were found strongly correlated with EIR. High variability between SCRs from cross-sectional and longitudinal surveys was observed. In longitudinal studies, the alternative catalytic reversible model adjusted better with serological data than the catalytic model. Clinical malaria attacks and malaria control interventions were found to have significant effect on seroconversion.DiscussionThe results of the study suggested that crude extract was a good serological tool that could be used to assess the level of malaria exposure in areas where malaria transmission is declining. However, additional parameters such as clinical malaria and malaria control interventions must be taken into account for determining serological measurements for more accuracy in transmission assessment.

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