RESUMO
The hypotheses put forward to explain the malaria transmission cycle in extra-Amazonian Brazil, an area of very low malaria incidence, are based on either a zoonotic scenario involving simian malaria, or a scenario inwhich asymptomatic carriers play an important role. Objectives: To determine the incidence of asymptomatic infection by detecting Plasmodium spp. DNA and its role inresidual malaria transmission in a non-Amazonian region of Brazil. Methods: Upon the report of the first malaria case in 2010 in the Atlantic Forest region of the state of Espírito Santo, inhabitants within a 2 km radius were invited to participate in a follow-up study. After providing signed informed consent forms, inhabitants filled out a questionnaire and gave blood samples for PCR, and thick and thin smears. Follow up visits were performed every 3 months over a 21 month period, when new samples were collected and information was updated. Results: Ninety-two individuals were initially included for follow-up. At the first collection, all of them were clearly asymptomatic. One individual was positive for Plasmodium vivax, one for Plasmodium malariae and one for both P.vivax and P. malariae, corresponding to a prevalence of 3.4% (2.3% for each species). During follow-up, four new PCR positive cases (two for each species) were recorded, corresponding to an incidence of 2.5 infections per 100 person years or 1.25 infections per 100 person-years for each species...