Challenges and opportunities for pursuing malaria elimination in Peru
Quispe, Antonio Marty
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Recent history suggests that malaria can be eliminated in low-endemic countries, and there is a growing interest among key stakeholders from Peru to plan accordingly and achieve malaria elimination with a comprehensive programmatic goal. In support of this interest, this dissertation integrates a course of studies to inform and support such goal, by accounting for the two most important malaria transmission patterns that currently characterize Peru, the one affecting the Peruvian north coast and the other affecting the Peruvian Amazon basin. The first study will determine the impact of reactive case detection with focal mass drug administration (RCD/FMDA) as compared to passive case detection on reducing the regional annual parasite incidence in Tumbes, Peru (Paper 1). The second study will determine the impact of the malaria elimination program implemented in Tumbes on interrupting the transmission of malaria beyond the intervention area and along the Peruvian north coast (Paper 2). And the third study will determine whether further understanding the patterns of malaria incidence in Loreto, the main human malaria reservoir in Peru, may offer a variety of strategical targets for the malaria elimination program that was launched in Loreto, influencing as well the nearby regions at the Peruvian Amazon basin in 2017 (Paper 3). It has been observed that the malaria elimination program implemented in Tumbes, which was based on replacing passive case detection with RCD/FMDA strategy, had a significant effect on reducing the regional annual parasite incidence in Tumbes within the intervention areas (2/13 districts) during the first two years of the program (pilot project). When the strategy was scaled up across the entire Tumbes region, malaria transmission was halted with no endogenous cases for the following three years. Additionally, data suggest that the Tumbes intervention indirectly helped to interrupt malaria transmission in the nearby region of Piura. During the intervention in Tumbes, nearby Piura districts also observed a decrease of their malaria weekly parasite incidence, ultimately reporting zero autogenous malaria symptomatic cases at the end of the study period. Based on the evidence generated by the two previous studies we explored the pattern of malaria transmission across the Loreto Region through riverine networks where the RCD/FMDA strategy may have a substantial effect on interrupting the transmission of malaria. Our data showed that the distribution of malaria cases does follow the Amazon river tributaries, which are areas competent to sustain the transmission of malaria from one season to the following. Furthermore, we observed that the main predictors of malaria in the region are low altitude and the density of the vegetation and that there are some differences in the distribution of falciparum malaria which seems to be more associated with the density of the vegetation than the distribution of vivax malaria. Among the different riverine networks, we identified some that appear to behave like independent foci of malaria transmission with only select communities demonstrating indices consistent with a year-round transmission, each of them representing potential targets for the RCD/FMDA strategy with a high likelihood to have a substantial effect on interrupting the transmission of malaria. Based on this information, achieving malaria elimination in Peru therefore appears feasible; however, it will require strongly epidemiological and data-driven approaches to optimize the effect of existing preventing interventions strategies. This will need to target well-characterized human malaria reservoirs in low endemic settings in order to maximize the effect of transmission-blocking drugs and effectively interrupt malaria transmission in limited-connected communities such as those in the Peruvian north coast and in the Peruvian Amazon.