Mobile Phone Microscopy Diagnoses Intestinal Worms

Scientists at Toronto General Hospital (ON, Canada) working with colleagues in Tanzania, evaluated a total of 199 Kato-Katz thick smears by both mobile phone microscopy and conventional microscopy. The microscopist manually manipulated the slide underneath the mobile phone microscope to examine the entire area of stool on the slide. The thick double-sided tape that held the ball lens to the mobile phone provided a 1-mm buffer zone between the slide and ball lens. In addition, the cellophane strip placed over stool on the slide prevented the ball lens from becoming contaminated with feces.

The investigators had transformed the mobile phone into a microscope by temporarily mounting a 3-mm ball lens (Edmund Optics; Barrington, NJ, USA) to the camera of an iPhone 4S (Apple, Cupertino, CA, USA) with double-sided tape. Images were viewed on the mobile phone screen, and magnification was increased with the digital zoom function. It was estimated that this method could achieve an equivalent of 50–60 × magnification.

The cell phone microscope sensitivity was dependent on the type of worm and the strength of the infection. For example, the cellphone found 81% of infections of giant roundworm (Ascaris lumbricoides) and 54% of whipworm infections (Trichuris trichiura). However, the device only detected 14% of all hookworm infections, due to the much smaller number of eggs present than with the other parasites.

Isaac Bogoch, MD, an infectious disease specialist and the study's lead author said, “It was quite successful at detecting moderate to heavy infections, but not very good at detecting mild infections where there might be only a few eggs in the sample. I am confident that in the near future we will see cell phone microscopes widely used in low-resource settings. They are easy to make, portable, and today, you can find mobile phones with cameras even in some of the most remote regions in the world." The whole set up can be developed for USD 15, in addition to the cost of the phone, and can be assembled in five minutes. The study was published on March 11, 2013, in the American Journal of Tropical Medicine and Hygiene.

Related Links:
Toronto General Hospital
Edmund Optics
Apple