US registers rise in highly infectious norovirus causing stomach illness

CDC says positive tests for virus, which causes nausea, diarrhea and stomach pain, peaked at 16% in January

The US is seeing a rise in the norovirus informally called the stomach flu or stomach bug, according to the American Centers for Disease Control and Prevention (CDC), with positive tests for the contagious illness peaking at 16% in January.

The rise in infections spans the US, according to the healthcare agency, with infection rates not seen since last spring.