Water supply services need rapid ways of checking contamination in drinking water supplies, including norovirus, which causes intestinal distress. Scientists are trying to facilitate testing for the virus.
Rehan Hasan / EyeEm / Getty Images / EyeEm
Rehan Hasan / EyeEm / Getty Images / EyeEm
Water suppliers need quick ways to check for contamination in the supply of drinking water, including norovirus, which causes intestinal distress. Scientists are trying to make the virus easier to test.
Rehan Hassan / EyeEm / Getty Image / EyeEm
The norovirus tends to tell the news when an outbreak of cruise ships occurs. But the virus affects many more people than vacationers in the ocean.
The Centers for Disease Control and Prevention estimates that approximately 20 million people suffer from acute bowel disease from norovirus each year in this country. It is responsible for more than half of all cases of foodborne illness in the United States.
It may also fall into municipal water supplies when old pipes or storm overflows cause pollution of the wastewater by norovirus with drinking water.
"When we have a massive epidemic related to drinking water quality, the norovirus is likely to cause this infection," says environmental biologist Kelly Reynolds of Arizona Mel University and Enid Zuckerman of Tucson Public Health College.  Water suppliers regularly check for contamination, but Reynolds says existing norovirus tests take time and require sophisticated laboratory equipment.
So when Tucson's water program turned to her for help to improve the status quo, Reynolds thought she knew how to find a cheaper and faster approach.
The norovirus test he developed also uses microfluidic chips on paper. These are cheap waffles that draw water samples on them, so no external pumps are needed.
Even with the magnification available, the viruses are too small to see. Thus, Ion mixed an aqueous sample with small fluorescent polystyrene beads coated with antibodies to norovirus. If the virus is in the sample water on the paper chip, the balls will stumble around the virus, making it possible for the cellphone camera to detect them.
Ion says the device works fast.
"From trial to answer … five minutes," he says.
Ion provided details of his invention on August 27 at the National Meeting of the American Chemical Society in San Diego. A document describing preliminary results with the device was published in ACS Omega .
Although most norovirus infections are derived from the consumption of contaminated food, conducting a sensitive enough test to reliably detect the virus in water samples "would be helpful," says Rachel Noble, Mary and Watts Hill, Jr., a distinguished professor in the department of Environmental Sciences at the University of North Carolina.
As a result of hurricanes and other storms, flooding can lead to sewage systems overflowing, potentially mixing with drinking water. Municipal water system managers would breathe easier if they could be sure that they should not have to worry about norovirus infection at all.
She says she and other researchers have worked on similar projects to develop a rapid norovirus test. Ion's device shows promise, but "a lot of those ideas work in the lab," Noble says. Unfortunately, after being tested in the real world, they tend to not work as well. False negatives are especially undesirable, ie. declaring a water virus free when it really isn't.
"There may be only a few viral particles in a water system," Noble says. But these few particles can still cause disease and can be missed in a test sample.
The Yoon device still faces rigorous testing to ensure that it can accurately identify contaminated samples. So far, most tests are trying to make sure people can run the test reliably.
"Volunteers from my lab, some students and other lab staff just test the smartphone tool just to see how comfortable it is for the user," says Reynolds of Arizona. These are people with "very little knowledge of infectious disease or viruses or even water sampling," she adds.
Reynolds says the initial results are encouraging.
"We will transfer field tests to Tucson water officials in the fall," she says. This should help determine how reliable the new device is.