Modelling malaria incidence with environmental dependency in a locality of Sudanese savannah area, Mali - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Malaria Journal Année : 2009

Modelling malaria incidence with environmental dependency in a locality of Sudanese savannah area, Mali

Résumé

Background: The risk of Plasmodium falciparum infection is variable over space and time and this variability is related to environmental variability. Environmental factors affect the biological cycle of both vector and parasite. Despite this strong relationship, environmental effects have rarely been included in malaria transmission models. Remote sensing data on environment were incorporated into a temporal model of the transmission, to forecast the evolution of malaria epidemiology, in a locality of Sudanese savannah area. Methods: A dynamic cohort was constituted in June 1996 and followed up until June 2001 in the locality of Bancoumana, Mali. The 15-day composite vegetation index (NDVI), issued from satellite imagery series (NOAA) from July 1981 to December 2006, was used as remote sensing data. The statistical relationship between NDVI and incidence of P. falciparum infection was assessed by ARIMA analysis. ROC analysis provided an NDVI value for the prediction of an increase in incidence of parasitaemia. Malaria transmission was modelled using an SIRS-type model, adapted to Bancoumana's data. Environmental factors influenced vector mortality and aggressiveness, as well as length of the gonotrophic cycle. NDVI observations from 1981 to 2001 were used for the simulation of the extrinsic variable of a hidden Markov chain model. Observations from 2002 to 2006 served as external validation. Results: The seasonal pattern of P. falciparum incidence was significantly explained by NDVI, with a delay of 15 days (p = 0.001). An NDVI threshold of 0.361 (p = 0.007) provided a Diagnostic Odd Ratio (DOR) of 2.64 (CI95% [1.26;5.52]). The deterministic transmission model, with stochastic environmental factor, predicted an endemoepidemic pattern of malaria infection. The incidences of parasitaemia were adequately modelled, using the observed NDVI as well as the NDVI simulations. Transmission pattern have been modelled and observed values were adequately predicted. The error parameters have shown the smallest values for a monthly model of environmental changes. Conclusion: Remote-sensed data were coupled with field study data in order to drive a malaria transmission model. Several studies have shown that the NDVI presents significant correlations with climate variables, such as precipitations particularly in Sudanese savannah environments. Nonlinear model combining environmental variables, predisposition factors and transmission pattern can be used for community level risk evaluation.
Fichier principal
Vignette du fichier
1475-2875-8-61.pdf (642.29 Ko) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

insu-00412571 , version 1 (18-10-2023)

Identifiants

Citer

Jean Gaudart, Ousmane Touré, Nadine Dessay, A. Lassane Dicko, Stéphane Ranque, et al.. Modelling malaria incidence with environmental dependency in a locality of Sudanese savannah area, Mali. Malaria Journal, 2009, 8 (61), ⟨10.1186/1475-2875-8-61⟩. ⟨insu-00412571⟩
990 Consultations
1 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More