Malaria resurgence risk in Morocco depends, among other factors, on environmental changes as well as the introduction of parasite carriers. The aim of this paper is to analyze the receptivity of the Loukkos area, large wetlands in Northern Morocco, to quantify and to map malaria transmission risk in this region using biological and environmental data. This risk was assessed on entomological risk basis and was mapped using environmental markers derived from satellite imagery. Maps showing spatial and temporal variations of entomological risk for Plasmodium vivax and P. falciparum were produced. Results showed this risk to be highly seasonal and much higher in rice fields than in swamps. This risk is lower for Afrotropical P. falciparum strains because of the low infectivity of Anopheles labranchiae, principal malaria vector in Morocco. However, it is very high for P. vivax mainly during summer corresponding to the rice cultivation period. Although the entomological risk is high in Loukkos region, malaria resurgence risk remains very low, because of the low vulnerability of the area. 1. Background Until recently, malaria was endemic in Morocco. Three plasmodial species were present: Plasmodium falciparum, P. vivax, and P. malariae. Plasmodium falciparum was the dominant species until the beginning of the 1950s, when P. vivax became more important [1]. The most affected areas were those, which were most inundated, mainly the plains comprising swamps, which are the main breeding sites of the major vector in Morocco: Anopheles labranchiae. Drainage and irrigation projects, undertaken at the beginning of the twentieth century have contributed to the reduction of malaria transmission, but disease was still common in the early 1960s. In 1965, a National Malaria Control Program was launched. It was based on vector control using DDT indoor residual spraying and parasite reservoir control by treatment and chemoprophylaxis. The effect on P. falciparum transmission was rapid, and the last autochthonous case was notified in 1973. Thirty years later, it was possible to interrupt P. vivax transmission. In 2008, Morocco undertook the process for certification of malaria-free status according to WHO criteria. However, Morocco still reports, every year, about one hundred of imported malaria cases. These are mainly detected in large urban areas, mainly Casablanca and Rabat, but also Fes and Agadir. Most of imported cases are P. falciparum originating from sub-Saharan Africa [2, 3]. Thus, malaria resurgence in Morocco remains a risk, because vectors are present in formerly
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