The Impact of Sustained Malaria Control in the Loreto Region of Peru: A Retrospective, Observational, Spatial Interrupted Time Series Analysis of the Pamafro Program

Background: Substantial investment in malaria control worldwide has led to dramatic declines in transmission since 2000. However, progress has stalled, and in settings where funding for malaria control has been withdrawn, malaria has been resurgent. Therefore, we aimed to assess the effect of the Project for Malaria Control in Andean Border Areas (PAMAFRO) on malaria incidence across the Loreto region of Peru. Methods: We conducted a retrospective, observational, spatial interrupted time series analysis of malaria incidence among people reporting to health posts across the Loreto region of Peru between January 2000 and December 2011. We used information on the number of diagnosed cases of Plasmodium vivax and Plasmodium falciparum, as determined by microscopy. We also used data on environmental variables associated with malaria transmission, including temperature, precipitation, soil moisture, soil temperature, and windspeed, which were derived from a Land Data Assimilation System designed for the Amazon region. We used census data to define the population at risk. We used Bayesian spatio-temporal modeling techniques to estimate the impact of the PAMAFRO program. Findings: During the PAMAFRO program, incidence of P. vivax declined from 42.8 cases/1,000 people/year to 10.1 cases/1,000 people/year. Incidence for P. falciparum declined from 14.3 to 2.5 cases/1,000 people/year over this same period. The effects of PAMAFRO-supported interventions varied both by geography and species of malaria. Interpretation: The PAMAFRO program was wildly successful, but reductions in transmission were not sustained after the program ended. Malaria control programs must ensure continued financing of malaria control programs to sustain reductions in transmission. Funding: National Aeronautics and Space Administration, and the National Institutes of Health Declaration of Interest: We declare no conflicts of interest Ethical Approval: This study analyzes publicly-available, de-identified, secondary data, and therefore did not require ethics approval