Molecular surveillance detects high prevalence of the neglected parasite Mansonella ozzardi in the Colombian Amazon.

Mansonellosis is an under-mapped insect-transmitted disease caused by filarial nematodes that are estimated to infect hundreds of millions of people. Despite their prevalence, there are many outstanding questions regarding the general biology and health impacts of the responsible parasites. Historical reports suggest that the Colombian Amazon is endemic for mansonellosis and may serve as an ideal location to pursue these questions. We deployed molecular and classical approaches to survey Mansonella prevalence among adults belonging to indigenous communities along the Amazon River and its tributaries near Leticia, Colombia. Loop-mediated isothermal amplification (LAMP) assays on whole-blood samples detected a much higher prevalence of Mansonella ozzardi infection (∼40%) compared to blood smear microscopy or LAMP performed using plasma, likely reflecting greater sensitivity and the ability to detect low microfilaremias and occult infections. Mansonella infection rates increased with age and were higher among males. Genomic analysis confirmed the presence of M. ozzardi that clusters closely with strains sequenced in neighboring countries. We successfully cryopreserved M. ozzardi microfilariae, advancing the prospects of rearing infective larvae in controlled settings. These data suggest an underestimation of true mansonellosis prevalence, and we expect that these methods will help facilitate the study of mansonellosis in endemic and laboratory settings.