Z Gastroenterol 2009; 47 - A15
DOI: 10.1055/s-0029-1223994

Phylogenetic analysis of a hepatitis C virus outbreak in a haemodialysis unit

Á Dencs 1, A Hettmann 1, M Szűcs 2, E Rusvai 1, M Takács 1
  • 1National Center for Epidemiology, Division of Virology, Budapest, Hungary
  • 2National Public Health and Medical Officer Service, Department of Epidemiology, Pécs, Hungary

Introduction:

Since the screening of blood donors has been introduced, transfusion-associated hepatitis C infections have become rare events. However, a part of newly acquired HCV infections are still health-care related. By the phylogenetic analysis of viral sequences the relatedness of new infections can be demonstrated.

In this study we aimed to find molecular evidence for a nosocomial transmission and to ascertain the source of infections at a haemodialysis center in Hungary. 25 seropositive patients were included in the analysis, 4 of them had been known hepatitis C virus carriers previous to haemodialysis and were considered possible source patients.

Methods:

Regions of the HCV genome with different levels of variability were utilized for the investigation. A sensitive nested PCR specific for the conserved 5'UTR was applied to detect viral RNA. The more variable NS5B region was also amplified and sequenced for genotyping and phylogenetic analysis. Fifteen unrelated control sequences from Hungary were used for comparison.

Results:

Out of 25 seropositive patients 16 were HCV RNA positive using 5'UTR primers. 15 of them were also positive using primers for NS5B. Genotyping showed that all viruses were genotype 1b. Sequences of newly infected patients were genetically very close and formed a separate group from control sequences with high statistical support, showing that they were probably related. Based on the phylogenetic analysis, 3 of the putative source patients carried viruses unrelated to the outbreak. The viral sequence of the fourth putative source patient, however, clustered together with the sequences of the patients infected during the outbreak, which strongly suggested that the virus of this patient was the source of the nosocomial infections.

Conclusions:

The grouping and genetic distances between isolates suggest that the 11 newly infected patients included in the phylogenetic analysis were infected from a common source, which was identified as the virus of a HCV carrier patient also haemodialysed at the same unit.