A smartphone app can detect signs of norovirus, the most common cause of gastroenteritis.
Jeong-Yeol Yoon and his colleagues at the University of Arizona in the US built the system using a microscope attachment for a smartphone and a separate light source. Combined they can detect low levels of norovirus in water.
The technique is sensitive enough to detect as little as 10 attograms (10−18 grams) of norovirus per millilitre, which is six orders of magnitude better than other portable detectors, says Yoon. As few as tens of norovirus particles are enough to make people sick, he says.
Also known as the winter vomiting bug, norovirus is notorious for causing outbreaks of vomiting and diarrhoea in crowded situations, such as on cruise ships.