Scientists working in rural Tanzania have used a simple $8 glass lens, a strip of double-sided tape, and a cheap flashlight to convert an Apple iPhone into a field microscope that can detect intestinal worm infections in children.
The scientists used the cell phone microscope to evaluate 199 children's stool samples that had been prepared on a typical laboratory slide. The children were participating in a clinical trial on Pemba Island in Tanzania that was testing the efficacy of different drug treatments for eliminating intestinal worms.
To examine a stool sample, the researchers covered the slide in cellophane to prevent contamination, used double-sided tape to attach it to the camera, lit it from underneath with the flashlight, and then took an image of the sample.
Though the iPhone microscope was not as sensitive as a light microscope - the gold standard for detecting intestinal worms in stool samples, Dr. Isaac Bogoch, an infectious disease specialist at Toronto General Hospital (Toronto, Canada;www.uhn.ca) and his colleagues believe that, with a few adjustments, it can come very close.
Overall, the cell phone microscope detected evidence of intestinal worm infections (by revealing the presence of eggs) in about 70% of the samples that had been deemed infected using a light microscope.
The sensitivity of the cell phone microscope varied greatly depending on the type of worm and the intensity of infection. It detected 81% of infections with giant roundworm (A. lumbricoides) and 54% of roundworm infections (T. trichiura). However, it revealed only 14% of all hookworm infections, which the researchers attributed to the fact that the hookworm infections had left far fewer eggs than the other parasites.
"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," says Dr. Bogoch.
Vision Systems Articles Archives