[1] Univ Helsinki, Cent Hosp, Dept Med, Div Gastroenterol, FIN-00290 Helsinki, Finland
[2] Univ Helsinki, Haartman Inst, Dept Bacteriol & Immunol, FIN-00290 Helsinki, Finland
[3] Univ Helsinki, Cent Hosp, Diagnost Lab, FIN-00290 Helsinki, Finland
[4] Univ Helsinki, Cent Hosp, Jorvi Hosp, Dept Pathol, Espoo, Finland
[5] Univ Helsinki, Cent Hosp, Peijas Hosp, Dept Pathol, Vantaa, Finland