Temporal and micro-spatial heterogeneity in transmission dynamics of co-endemic Plasmodium vivax and Plasmodium falciparum in two rural cohort populations in the Peruvian Amazon

Abstract

Background
Malaria is highly heterogeneous; its changing malaria micro-epidemiology needs to be addressed to support malaria elimination efforts at the regional level.
Methods
A three-year, population-based cohort study in two settings in the Peruvian Amazon (Lupuna, Cahuide) followed participants by passive and active case detection from January 2013 to December 2015. Incidence and prevalence rates were estimated using microscopy and PCR.
Results
Lupuna registered 1,828 infections (1,708 P. vivax, 120 P. falciparum; incidence was 80.7 infections/100 person-years (95%CI [77.1–84.5]). Cahuide detected 1,046 infections (1,024 P. vivax, 20 P. falciparum, two mixed); incidence was 40.2 infections/100 person-years (95%CI [37.9–42.7]). Recurrent P. vivax infections predominated onwards from 2013. According to PCR data, submicroscopic predominated over microscopic infections, especially in periods of low transmission. The integration of parasitological, entomological and environmental observations evidenced an intense and seasonal transmission resilient to standard control measures in Lupuna, and a persistent residual transmission after severe outbreaks were intensively handled in Cahuide.
Conclusion
In two exemplars of complex local malaria transmission, standard control strategies failed to eliminate submicroscopic and hypnozoite reservoirs, enabling persistent transmission.