Historical importance of wetlands in malaria transmission in southwest of Spain.

Malaria is a parasitic disease that is currently affecting a good number of countries with approximately one million deaths per year. Traditionally, this pathology has been related to wetlands and other unhealthy water bodies. It disappeared from most of Western Europe after the Second World War; however, its eradication from Spain took place later. In fact, the WHO didn’t of cially declare malaria in Spain eradicated until 1964, after a gradual controlled process of the illness, through the improvement of health and hygienic conditions in the country, and the ght against the vectors, the parasite, and its reservoirs. In 1913, the Spanish regions with the largest number of municipalities with autochthonous malaria were, precisely, those containing larger areas covered by unhealthy water bodies (except for Extremadura). Among them, Western Andalusia outstood as the main region with the largest area of unhealthy malaria focuses and with high mortality and morbidity rates. Within Western Andalusia, Huelva —and especially its coastal areas— has been, for centuries, one of the provinces with greater endemicity. After the Spanish Civil War a process of reforestation with fast-growing species took place in the Coastal Aeolian Sheet of the Province of Huelva, which led to an 88% reduction of the surface covered by ponds in this territory. These lagoons had started a natural regression process by the end of the XIXth Century related to the post-Little Ice Age warming in Andalusia. The parallel evolution of malaria patients and the regression process experienced by these wetlands for the above mentioned reasons have had a determinant in uence in the eradication of the disease. All of this leads us to consider the relevant role of wetlands when studying the future risk of malaria reemergence in SW Spain