Cell phone diagnostics? Close, but not quite a cigar

A team of researchers in Tanzania are getting lots of attention for adapting a smart phone to do worm infection diagnosis.

Close, but not quite. The team took an iPhone 4S, slapped on a glass lens with double sided tape and used a flashlight to see if intestinal worms are in stool samples.

The results may be promising, but not really too stunning an achievement or at the point where people should start putting lenses on $250 iPhones and use them as microscopes. The researchers call it a proof of concept, something desperately needed in the evidence-challenged field of mHealth.

“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,” said Isaac Bogoch, MD, an infectious disease specialist at Toronto General Hospital and the study’s lead author.

Intestinal worms infect an estimated 2 billion people around the world. Their impacts are long lasting, especially on children, and can cause problems like chronic anemia and malnutrition. It is worse for people living in poverty in the more remote areas of developing countries. People are infected through contaminated soil that is either ingested or transmitted via skin.

Fortunately, deworming school age children is cheap, easy and effective. A randomized control study conducted in western Kenya by Michael Kremer and Edward Miguel found that providing deworming medication to primary school students was the most cost effective way to boost attendance.

“Deworming increased school participation by at least 7 percentage points, which equates to a one-quarter reduction in school absenteeism,” found the researchers.An analysis of the estimated cost per equivalent live saved carried out by the charity evaluator GiveWell found that deworming is ‘in the same ballpark’ as distributing bednets against malaria.

Deworming campaigns are underway in schools in Kenya and India, but there are cases where people with intestinal worms do not know that they have them. Developing a simple and effective tool to determine if a person has intestinal worms in resource-strapped settings can help to address the problem.

“There’s been a lot of tinkering in the lab with mobile phone microscopes, but this is the first time the technology has been used in the field to diagnose intestinal parasites,” said Bogoch.

The iPhone microscope varried in its efficacy. It detected 81% of giant roundworm infections, but only 14 percent of all hookworm infections. The difference between the two is that the hookworm had left far fewer eggs than the other parasites. The reseachers estimate that a phone would have to detect at least 80% of infections before it would be put to use in a clinical setting.

“From a practical standpoint, the sensitivity for diagnosing any soil-transmitted helminth egg with the mobile phone microscope was close to 70%, and although it is not sensitive enough for immediate application, it is getting close to acceptable diagnostic characteristics,” says the study.

Currently, infections are determined by using $200 electrical powered microscopes. The slightly more expensive iPhone with the inexpensive attachments provide a mobile alternative that could potentially be cheaper in the coming years.

“I have nothing but praise for the ingenuity of scientists using all available tools to solve pressing health problems in some of the poorest parts of the world,” said David H. Walker, MD, president of the American Society of Tropical Medicine and Hygiene. “This study is an illustration of how a modest investment in tropical disease research can help reap enormous health benefits for children.”