The nosocomial transmission of hepatitis C involving three subjects pa
rticipating in a research project in a Swedish hospital is described.
One person contracted acute hepatitis C and another participant had an
asymptomatic seroconversion. A temporal relationship between particip
ation in the experiments and seroconversion for hepatitis C, and virol
ogy with phylogenetic analyses, suggest that they most probably contra
cted hepatitis C from a third subject who unknowingly had chronic hepa
titis C. Faulty nursing and procedural routines were identified as the
probable cause of the transmission. Our findings reinforce the need f
or medical personnel to strictly adhere to universal precautions worke
d out to prevent the transmission of blood-borne viruses and underline
the importance of a continuous supervision of nursing and procedural
routines, even in hospitals with well-educated staff and presumably hi
gh standards.