Following the severe malaria outbreak in the central highlands in Madagascar in 1986, a vector control program by use DDT pm 75 house-spraying has been implemented to operate in areas located at altitudes between 1000 and 1500 m. Early treatment with chloroquine has also been incorporated in the control program. To detect areas at particular high risk for malaria outbreak the Geographic Information System (GIS) has been applied and tested. The study has shown that the system can be used in malaria surveillance in order to identify areas in which an intense distribution of Anopheles funestus can be anticipated and, hence, targeted in spraying campaigns. The system may also be used to monitor changes in anti-malarial drug resistance, in addition, to control of other vector-born diseases.

RESUME : Depuis la réinvasion des Hautes Terres Centrales par Anopheles funestus, ayant entraîné l'épidémie meurtrière du paludisme à partir de 1986, la lutte antipaludique, à Madagascar, associe la lutte antivectorielle et la chimiothérapie précoce. Des opérations de pulvérisation intra-domiciliaire de DDT pm 75 ont été menées depuis 1988 sur les Hautes Terres, d'abord entre les altitudes de 1000 à 1500 mètres, puis dans les foyers épidémiques déclarés par les postes sentinelles de surveillance épidémiologique (PSSE) implantés par la Coopération Italienne. L'objectif de ce système d'alerte est surtout de prévenir de nouvelles épidémies. Le recours à d'autres outils, tels les Systèmes d'Information Géographique (SIG) et la télédétection, semble alors intéressant pour compléter cette stratégie. Ils contribuent à la détermination des gîtes larvaires très productifs d'An. funestus, essentiellement les rizières. Cette étude permettra d'élaborer un modèle prédictif qui peut servir à cibler les zones à pulvériser. Ainsi, les SIG constituent des outils d'aide à la décision. La surveillance de la résistance aux antipaludiques est une autre forme de stratégie de lutte contre le paludisme. Plusieurs facteurs interviennent dans l'évolution de cette résistance. La constitution des SIG sur la résistance visera à intégrer des données spatiales et temporelles qui peuvent mieux faire comprendre cette évolution. Les données obtenues grâce aux SIG et à la télédétection, lors de cette étude, peuvent être utilisées dans les programmes de luttes contre d'autres maladies à transmission vectorielle existantes à Madagascar. Il faudra alors tenir compte des facteurs environnementaux spécifiques de chaque maladie. Mots-clés : Paludisme - Programme de lutte - Système d'Information Géographique - Madagascar. ABSTRACT : "Geographic Information System as a supplementary tool in malaria control in Madagascar" : Following the severe malaria outbreak in the central highlands in Madagascar in 1986, a vector control program by use DDT pm 75 house-spraying has been implemented to operate in areas located at altitudes between 1000 and 1500 m. Early treatment with chloroquine has also been incorporated in the control program. To detect areas at particular high risk for malaria outbreak the Geographic Information System (GIS) has been applied and tested. The study has shown that the system can be used in malaria surveillance in order to identify areas in which an intense distribution of Anopheles funestus can be anticipated and, hence, targeted in spraying campaigns. The system may also be used to monitor changes in anti-malarial drug resistance, in addition, to control of other vector-born diseases. Key-words : Malaria - Control program - Geographic Information System - Madagascar.

Epidemiological surveillance and control of malaria in the central highlands in Madagascar from 1998 to 2000" : The central highlands in Madagascar are characterized by an unstable occurrence of malaria with the risk of sporadic outbreaks. In major parts of the region DDT indoor spraying campaigns have been carried out from 1993 to 1998. This strategy was in 1999 replaced by another anti-vector intervention program targeting residual foci as detected by a surveillance and early warning system. This system is based on monitoring of presumptive malaria cases in the communities by which the number of presumptive cases exceeded a defined warning threshold value per month. The system was in the follow-up period shown to be very sensitive to variation of the coverage of anti-vector interventions: the number of presumptive cases decreased in the villages in which indoor spraying had been carried out and a minor increase was observed in those villages, where indoor spraying has been suspended. An increase of malaria cases was observed in 44 (20,8%) out of 212 study sites in the same period. The increase was in particular predominant in areas at lower attitude at the outer zones of the central highlands.