Case-control study on Puumala virus infection: smoking is a risk factor Vapalahti, K.; Virtala, A.-M.; Vaheri, A.; Vapalahti, O. Epidemiology and Infection 138(4): 576-584 2010 1469-4409 10.1017/s095026880999077x https://eurekamag.com/research/034/536/034536043.php