The coronavirus was already present in two large cities in northern Italy in December, over two months before the first case was detected, a national health institute study of waste water has found. Researchers discovered genetic traces of Sars-Cov-2 -- as the virus is officially known -- in samples of waste water collected in Milan and Turin at the end of last year, and Bologna in January, the ISS institute said in a statement seen by AFP Friday. Italy's first known native case was discovered mid-February. ide/cjo/txw