Handheld mobile microscopes diagnosing intestinal parasites

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MicroscopesHandheld, mobile phone-based microscopes can be used in developing countries to diagnose intestinal parasites quickly and accurately – and after minimal training of community laboratory technicians – reports a study conducted in Côte d’Ivoire in West Africa.

The first-of-its-kind, community-based research 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.

“We wanted to know if we could put these portable field microscopes into the hands of individuals who would use them in day-to-day settings, and whether they would be effective. We wanted to see how they would work in real-world situations where there are few labs,” said Dr Isaac Bogoch, senior author and physician in internal medicine and infectious diseases at Toronto General Hospital, University Health Network.

Intestinal worms affect almost 2bn people world-wide, predominantly in areas with poor sanitation and unsafe water. In children, these parasites may lead to malnutrition, stunted growth and development and can lead to chronic disability, with serious health and economic consequences.

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

Bogoch and his team tested two portable handheld microscopes: a commercial Newton Nm1 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, “gold” standard microscope.

The two 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.

“It was heart-warming to see how well and easily these portable, handheld field microscopes were adopted and used in a rural setting,” said Bogoch, who is also a clinical researcher at the Toronto General Research Institute. “This will help us map out the areas of greatest need.” He adds 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.

Accurate, portable, battery-powered microscopes which can deliver quality diagnostics to the poorest of the poor in underserviced areas can significantly ease the severe burden of infectious diseases, says Bogoch.

Abstract
Background: Handheld light microscopy using compact optics and mobile phones may improve the quality of health care in resource-constrained settings by enabling access to prompt and accurate diagnosis.
Methodology: Laboratory technicians were trained to operate two handheld diagnostic devices (Newton Nm1 microscope and a clip-on version of the mobile phone-based CellScope). The accuracy of these devices was compared to conventional light microscopy for the diagnosis of Schistosoma haematobium, S. mansoni, and intestinal protozoa infection in a community-based survey in rural Côte d’Ivoire. One slide of 10 ml filtered urine and a single Kato-Katz thick smear from 226 individuals were subjected to the Newton Nm1 microscope and CellScope for detection of Schistosoma eggs and compared to conventional microscopy. Additionally, 121 sodium acetate-acetic acid-formalin (SAF)-fixed stool samples were examined by the Newton Nm1 microscope and compared to conventional microscopy for the diagnosis of intestinal protozoa.
Principal Findings: The prevalence of S. haematobium, S. mansoni, Giardia intestinalis, and Entamoeba histolytica/E. dispar, as determined by conventional microscopy, was 39.8%, 5.3%, 20.7%, and 4.9%, respectively. The Newton Nm1 microscope had diagnostic sensitivities for S. mansoni and S. haematobium infection of 91.7% (95% confidence interval (CI) 59.8–99.6%) and 81.1% (95% CI 71.2–88.3%), respectively, and specificities of 99.5% (95% CI 97.0–100%) and 97.1% (95% CI 92.2–99.1%), respectively. The CellScope demonstrated sensitivities for S. mansoni and S. haematobium of 50.0% (95% CI 25.4–74.6%) and 35.6% (95% CI 25.9–46.4%), respectively, and specificities of 99.5% (95% CI 97.0–100%) and 100% (95% CI 86.7–100%), respectively. For G. intestinalis and E. histolytica/E. dispar, the Newton Nm1 microscope had sensitivity of 84.0% (95% CI 63.1–94.7%) and 83.3% (95% CI 36.5–99.1%), respectively, and 100% specificity.
Conclusions/Significance: Handheld diagnostic devices can be employed in community-based surveys in resource-constrained settings after minimal training of laboratory technicians to diagnose intestinal parasites.

Authors
Jean T Coulibaly, Mamadou Ouattara, Michael V D’Ambrosio, Daniel A Fletcher, Jennifer Keiser, Jürg Utzinger, Eliézer K N’Goran, Jason R Andrews, Isaac I Bogoch

University Health Network material
PLOS Neglected Tropical Diseases abstract


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