M. Olmer et al., TRANSMISSION OF THE HEPATITIS-C VIRUS IN AN HEMODIALYSIS UNIT - EVIDENCE FOR NOSOCOMIAL INFECTION, Clinical nephrology, 47(4), 1997, pp. 263-270
Hepatitis C virus (HCV) infection is a frequent feature in hemodialysi
s (HD) patients. The way of viral transmission is difficult to establi
sh, but in previous studies the role of blood transfusions and of HD t
reatment duration, and the possibility of nosocomial transmission of t
he virus have been suggested. We present here the results of a virolog
ical follow-up of HCV infection in our HD unit in 1993-1994, and a mol
ecular study of viral strains that led to a possible reconstruction of
viral spreading. All patients in our unit were regularly tested for a
lanine aminotransferase, HCV antibodies and HCV RNA in serum. Seven se
roconversions were detected during follow-up, and a high proportion of
type 1b HCV strains was found in infected patients. Nucleotide sequen
ces located in the envelope 1 (E1) viral coding region of type 1b stra
ins were compared in our patients and numerous controls infected with
the same HCV genotype. A high proportion of patients with antibodies t
o HCV were detected in our unit (32.5%). Blood transfusions and durati
on of HD treatment were risk factors for HCV infection. Seroconversion
s in patients never transfused and predominance of type 1b HCV strains
suggested that infection had occurred via the nosocomial pathway in o
ur unit. Similar sequences in the E1 region were found in four patient
s treated, forming a distinct cluster in a phylogenetic tree. Of these
four patients, two had been infected before 1991, and the others made
a seroconversion for HCV at the same period in 1994. In all other pat
ients, including a nurse who had been in charge of some infected patie
nts, distinct strains were found. Duration of HD treatment seems to be
a major factor of risk for HCF infection in HD units. Contamination c
ould occur during blood transfusion or via the nosocomial pathway thro
ugh a crossinfection mechanism from patients already infected. The lat
ter mechanism was formally demonstrated in this study.