The notorious norovirus, commonly responsible for causing outbreaks on cruise ships, can be blamed for ruining many vacations by causing diarrhea, severe vomiting, and stomach pain. The highly infectious virus can cause water-borne and food-borne outbreaks in municipal water systems, schools, and restaurants. To make the norovirus detection easier, researchers have developed a sensitive and portable device that can detect even the smallest amount of norovirus in water.
“It only takes a very small number of norovirus particles to cause an infection in humans, so we need a really sensitive detection method,” says Jeong-Yeol Yoon, Ph.D., who led the team. “Also, scientists aren’t able to culture norovirus in the lab, and available antibodies to the pathogen aren’t very strong.”Due to this, detecting smaller amounts of norovirus in water and food samples was very difficult because it involved a polymerase chain reaction-based method, which takes a lot of time and could only be conducted in a lab by a trained professional.
During previous research, Yoon and his team at the University of Arizona engineered a smartphone-based device that was capable of detecting low levels of norovirus by measuring the light scattered by the virus-infected polystyrene beads in a paper microfluidic chip. “Even though our detection limit was really low, the problem was that norovirus can be infectious at even lower concentrations,” Yoon says. “When we talked about this work at conferences, the feedback we received was that we need to provide an even easier method that can detect much lower concentrations of virus.”
To rectify the error, the researchers now used a fluorescence instead of light scattering to detect norovirus. The researchers modified an ordinary smartphone into a fluorescence microscope by attaching a light microscope accessory. The team clicked photographs of the chip which was detecting the norovirus particles. The application detected the amount of norovirus by calculating the pixel count of the images. The low limit was 5-6 norovirus particles per sample, which is very close to the single-virus level, as 10 particles can cause illness in people.
Currently, Yoon and his team are trying to develop a smartphone-based device that could detect norovirus infections in patients before they reach a lethal stage. To detect norovirus in the human body, they are going to analyze fecal samples. “When norovirus reaches levels detectable by other methods, the person is already seriously ill,” Yoon says. “But if we can detect the virus earlier, they can receive medical care sooner.” The team believes that early detection of the virus can help curb the disease in isolated and crowded places like cruise ships so that the patient could consider treatment as early as possible.