In spite of its localization near the city of Belém, Pará, Cotijuba Island has been the site of outbreaks of malaria during recent years, especially in the months of April and May. The island is part of an archipelago at the southern margin of Marajó Bay, located 29 km from Belém, as an island portion of the municipality of Belém. The island has a total area of about 60 km² and 20 km of beaches that correspond to about 66% of the total area. Because of the epidemic, it tias become necessary to identify the anopheline species that are the malaria vectors on the island. From 2002 to 2004 periodic collections were made of mosquito larvae and adults, and their breeding sites were located and characterized. Larvae were collected with dippers, while adults were collected manually in individual tubes from human volunteers. Two collections were made of adults in forested areas, one collection during the dry season and the other during the rainy season. Each collection was made during a continuous 24 hour period. Six bi-monthly collections were made near residents' houses, each lasting 6 hours. Both in the forest and near houses, only two species of anophelines were found to bite people, Anopheles (Nyssorhynchus) aquasalis and Anopheles (Anopheles) intennedius. A. aquasalis was more common near houses, whereas A. intermedius was more common in the forest. Most of the island's malaria cases were found to occur two months after the beginning of the rainy season, in the month of May. On all of Cotijuba Island there are four lakes that are possible anopheline breeding sites, and Gabriela Lake is the principal breeding site, responding for 42% of the malaria cases on the island during 2003. Climatic conditions, the resident population's behavior and housing, and the lack of resources for effective vector control, among other factors, favor the continual presence of malaria on Cotijuba Island.
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