Correction: Modification and optimization of the FECPAKG2 protocol for the detection and quantification of soil-transmitted helminth eggs in human stool.

[This corrects the article DOI: 10.1371/journal.pntd.

Rationale for Quality Assurance in Fecal Egg Monitoring of Soil-Transmitted Helminthiasis.

Substantial investment has been made into the once "neglected" tropical disease, soil-transmitted helminthiasis, and into control programs that operate within a framework of mapping baseline disease distribution, measuring the effectiveness of applied interventions, establishing when to cease drug administration, and for posttreatment evaluations. However, critical to each of these stages is the determination of helminth infection. The limitations of traditional microscope-based fecal egg diagnostics have not provided quality assurance in the monitoring of parasite disease and suboptimal treatment regimes provide for the potential development of parasite resistance to anthelmintic drugs.

Smartphone Microscopy of Parasite Eggs Accumulated into a Single Field of View.

A Nokia Lumia 1020 cellular phone (Microsoft Corp., Auckland, New Zealand) was configured to image the ova of Ascaris lumbricoides converged into a single field of view but on different focal planes. The phone was programmed to acquire images at different distances and, using public domain computer software, composite images were created that brought all the eggs into sharp focus.

Analysis of menisci formed on cones for single field of view parasite egg microscopy.

Parasite ova caused to accumulate in a single microscopic field simplifies monitoring soil-transmitted helminthiasis by optical microscopy. Here we demonstrate new egg-accumulating geometries based on annular menisci formed on the surface of a wetted cone. Fluidic features extracted from profile images of the system provided mathematical representations of the meniscus gradient that were compared quantitatively to numerical solutions of an axisymmetric Young-Laplace equation.

Quantitative particle microscopy in self-metered fluids.

We describe a simple device that volumetrically samples poured liquids and draws buoyant  materials into a single field of view for quantitative particle microscopy. Our approach relies on the formation of axisymmetric menisci and computational models of the static fluid developed using surface evolver showed close agreement with experiment. The apparatus was evaluated by counting pollen and demonstrated utility for the field analysis of microparticles.