A smartphone, a strip of double-sided tape and a simple glass lens could have a significant impact on the diagnosis of intestinal parasites that affect millions in remote, rural parts of the world, where even the most basic medical testing is hard to come by.
A recent, proof-of-concept study in rural Tanzania compared the effectiveness of a lens attached to an iPhone with the effectiveness of a standard light microscope in searching for roundworm and hookworm eggs in 199 children's stool samples. Although not as sensitive as the light microscope, the mobile phone microscope "revealed a sensitivity of 69.4 percent and a specificity of 61.5 percent for detecting any soil-transmitted helminth [parasitic worm] infection."
"Mobile phone microscopy has been used in the laboratory setting, but we thought it would be a good idea to test it in a real-world setting," Isaac Bogoch, the lead investigator of the study and a doctor at Toronto General Hospital, told IRIN. "We need to improve the image quality and get a better lens and better slides, but it is quite close to the gold standard."
"The advantage of the mobile phone microscope is that it's cheap: a smartphone - any phone with a decent camera and zoom would probably work as well as the iPhone - a glass lens that costs between US$8 and $10, and a basic flashlight. A lay health worker can do it, and the device is portable, which means it can be used as a point-of-care test," he added. "The standard diagnostic process requires a microscope, a person trained to use one, electricity and a decent light source, which is often not widely available in many places affected by parasitic infection."
According to the UN World Health Organization, close to one-quarter of the world's population is infected with soil-transmitted worms: "Over 270 million preschool-age children and over 600 million school-age children live in areas where these parasites are intensively transmitted, and are in need of treatment and preventive interventions."
Worms are transmitted by eggs in human faeces that contaminate the soil; transmission is exacerbated by poor sanitation. Children infected by worms can be physically, mentally or nutritionally impaired. A number of medications are available to control infection.
"We plan to test it in the clinical setting - the big picture is to get these diagnostic tests into the field, into the hands of people who need them most," Bogoch said.