Field Study Compares Portable Microscopes for Parasite Diagnosis

Handheld, mobile phone-based microscopes could be used in developing countries after minimal training of community laboratory technicians to diagnose intestinal parasites quickly and accurately.

A community-based study conducted by researchers from Toronto General Hospital and Toronto General Research Institute in the Republic of Côte d'Ivoire, West Africa, found that two different handheld microscopes could both effectively rule in individuals infected by parasites — important in allocating resources for public health screening — but varied in their sensitivity to detect all cases of an illness, in comparison to a conventional laboratory microscope.

A local laboratory technician in the Ivory Coast is trained on a portable, handheld microscope to detect intestinal parasites in a remote, rural community. These parasites affect almost 2 billion people worldwide, predominantly in areas with poor sanitation and unclean water. Courtesy of University Health Network.

Microscopes are vital in the diagnosis and surveillance of many parasitic infections, and are a staple in every clinical and public health lab worldwide, except in developing countries where parasitic infections are common.

The research team tested two portable handheld microscopes: a commercial Newton Nm1 portable field microscope, and a mobile phone-based CellScope, essentially a smartphone with a special custom-fitted lens attached over the camera and light source, developed by University of California engineers to detect intestinal parasites.

Local laboratory technicians were trained to operate the two handheld microscopes. In total, the technicians examined stool and urine samples from 226 individuals for the detection of parasites. The accuracy of all slides was evaluated by all microscopes: the two handheld devices, as well as a conventional, standard microscope.

The researchers reported that both handheld microscopes were very good at ruling in infections, and the Newton portable microscope was able to detect even very low-burden infections. The CellScope missed some low-burden infections, however, newer iterations of this device are currently being tested to increase its sensitivity.

The research was published in PLOS Neglected Tropical Diseases (doi: 10.1371/journal.pntd.0004768).

"It was heart-warming to see how well and easily these portable, handheld field microscopes were adopted and used in a rural setting," said Dr. Isaac Bogoch, senior author and physician in Internal Medicine and Infectious Diseases at Toronto General Hospital, University Health Network.

Bogoch said that novel diagnostic approaches for common parasitic infections could have a profound impact on care of patients, as well as on public health approaches to screening in resource-poor areas.