Evaluation of portable microscopic devices for the diagnosis of Schistosoma and soil-transmitted helminth infection

SUMMARY: The diagnosis of parasitic worm (helminth) infections requires specialized laboratory settings, but most affected individuals reside in locations without access to such facilities. We tested two portable microscopic devices for the diagnosis of helminth infections in a cross-sectional survey in rural Côte d'Ivoire. We examined 164 stool samples under a light microscope and then re-examined with a commercial portable light microscope and an experimental mobile phone microscope for the diagnosis of Schistosoma mansoni and soil-transmitted helminths. Additionally, 180 filtered urine samples were examined by standard microscopy and compared with the portable light microscope for detection of Schistosoma haematobium eggs. Conventional microscopy was considered the diagnostic reference standard. For S. mansoni, S. haematobium and Trichuris trichiura, the portable light microscope showed sensitivities of 84·8%, 78·6% and 81·5%, respectively, and specificities of 85·7%, 91·0% and 93·0%, respectively. For S. mansoni and T. trichiura, we found sensitivities for the mobile phone microscope of 68·2% and 30·8%, respectively, and specificities of 64·3% and 71·0%, respectively. We conclude that the portable light microscope has sufficient diagnostic yield for Schistosoma and T. trichiura infections, while the mobile phone microscope has only modest sensitivity in its current experimental set-up. Development of portable diagnostic technologies that can be used at point-of-sample collection will enhance diagnostic coverage in clinical and epidemiological settings.