Scientists in Uganda have devised a tool to test for vaginal infections that is so simple, even a child could—and did—make one.

In 2000, scientists at the Rakai Health Sciences Program in Kalisizo began studying the natural history of bacterial vaginosis, a common condition that lowers the acidity of the vagina. Using just a strip of pH paper, a bit of tape and a pediatric tongue depressor, they devised a 'swab' to measure vaginal pH.

Although the test itself was simple, coming up with a working design wasn't easy. “At that time we had never measured pH,” says Mary Sullivan, a former Rakai lab manager who now coordinates hepatitis research at Johns Hopkins University.

For a previous study of sexually transmitted diseases, the researchers had shown women in nearby villages how to use cotton swabs to collect their vaginal secretions. Although fluid from a cotton swab can be smeared onto pH paper, the swabs are not ideal for measuring pH because they may not release enough fluid for an accurate reading.

Swabs can also easily become contaminated. “If the swab stayed in the air too long, if it was put on a surface or dropped, that would affect the reading.” Sullivan says.

The researchers instead attached a four-inch strip of pH paper to a pediatric tongue depressor so that the measuring pad, which changes colors in response to the acidity of the environment, is at the tip. On either side is a color-coded pH key. “[The method] turned out to be very, very feasible,” says Noah Kiwanuka, an investigator at the Rakai Health Sciences Program who oversaw the field work.

Once the researchers had proved that the swab worked, they set up an assembly line in Sullivan's dining room and convinced her three daughters, then between the ages of six and ten, to help. “One of them would open the tongue depressor package and pass it to the next, who would put the strip over the top, and then the third one would put the tape around and put it back in the bag,” Sullivan says.

Simple solution: Women and children made swabs needed to test vaginal pH for a clinical study in Uganda. Credit: Rakai Health Sciences Program

The kids received their wages in gourmet gummy bears and M&Ms. On a good night, the team would make 200 swabs.

The researchers used the swabs to follow weekly changes in vaginal pH in 311 women over two years. “It's a poor woman's way of doing it,” says John Thorp, a gynecologist at the University of North Carolina, who was not involved in the project. “I think that taking the [vaginal] speculum out of it greatly diminishes the cost.”

Sullivan and her colleagues used to joke about patenting the swab. But it's too late. In July, New York–based company Vagisil launched its own over-the-counter version, a spatula-shaped 'wand' that measures pH.

The study ended in 2003, and the handmade pH swabs are no longer being used. But the researchers plan to revive their approach if necessary: a tube of pH strips and a box of tongue depressors are still cheaper than the $15 tab for a Vagisil kit.