[Control of malaria re-emergence in Reunion].

Réunion is currently posed with the operational problem of the last phase of the struggle against malaria, that is the consolidation and the maintenance of the state of cradication. The native parasite was eliminated, but the risk of resurgence of malaria remains on the island. This risk is even increasing from year to year because of the following: 1) the regular increase of the number of travellers originating from countries with malaria and consequently, the increase in the number of imported malaria cases; 2) the appearance of malaria strains resistant to amino-4-quinoleines, in the south-western regions of the Indian Ocean; 3) the persistence of the vector which cannot be eliminated because of its rapid evolutionary cycle and the multiplicity of its larval habitats. Furthermore, the reintroduction of malaria on the island would present serious consequences considering the disappearance of immunity in the population of Réunion. Thus it is necessary to maintain the struggle at a high level of intervention following a strategy based on: 1) the detection and the control of the malaria cases; 2) a targeted anti-vectorial activity based on a systematic anti-larval fight, eventually completed by the eradication of the adapted adult vectors. The reduction of personnel and the difficulties encountered in establishing a mechanization of the adapted tasks lead to a reduction of activities of insect eradication and endanger the existing strategy of the struggle. This strategy has been redefined during these last several years. The malaria situation in Réunion, satisfactory until today, rests on a careful epidemiological surveillance and on an optimized entomological surveillance. Currently, the treatments are abandoned in the least sensitive zones to the benefit of a better surveillance of priority zones (prospecting, entomological studies and treatments). Anopheles gambiae s.l. is present on the island and each year some parasites are imported to the Réunion territory. The requisite conditions for an eventual re-emergence of transmission of the native parasite would seem to be combined. However, this transmission is not observed. The role of the Applied Entomology Group is to evaluate the risk of malaria and to reorient, if necessary, the strategy of the antimalaria struggle in Réunion.