Nadal missed the Olympics and the U.S. Open and the early winter season, and ruled himself out of an expected return at the Australian Open with a stomach bug.

WSJ: Jason Gay: Nadal, Tennis's Snuffleupagus

Levels of the winter vomiting bug dipped over the Christmas period, but are likely to go up again as people return to work and school, experts say.

BBC: Winter vomiting bug norovirus levels dip over Christmas