Patients on renal replacement therapy are recognized as a group at increased risk of infection with hepatitis C virus (HCV). While the risk has been reduced by the use of erythropoietin for treatment of anaemia and the introduction of HCV screening of blood products and potential renal transplant donors, new cases of HCV are still being documented, with patients on hospital haemodialysis appearing to be particularly at risk. The exact mode of transmission of HCV within dialysis units is unclear, although there is evidence to support nosocomial transmission between patients. Third generation HCV antibody testing was performed on all dialysis patients when a new case of HCV was identified within our unit. Stored monthly serum samples were then examined retrospectively to determine when patients became HCV RNA and HCV antibody positive. Viral typing was carried out to identify the HCV strains responsible for transmission. Four new cases of HCV infection are described within a single dialysis shift. Viral typing identified two distinct strains of HCV as being responsible for these infections, both of which had previously been identified in dialysis patients within the unit known to have HCV infection. This information, taken in conjunction with knowledge of the location of each patient for dialysis, suggests two separate episodes of nosocomial transmission of HCV between haemodialysis patients. While evidence of nosocomial transmission of HCV is accumulating, with modern dialytic procedures evidence of transmission through the dialysis machine or equipment used for dialysis is lacking. This stresses the importance of strict applications of universal precautions as the key to prevention of further transmission of HCV infection. This information is obviously applicable not only to dialysis units but all units that may potentially come in contact with HCV patients.

Paired serum and saliva samples were collected simultaneously from 50 intravenous drug users with serologically proven hepatitis C virus infection. The oral health of the volunteers was also assessed. Hepatitis C virus RNA was detected by nested PCR, employing primers from the 5' noncoding region. Positive PCR products were sequenced using the Sequenase PCR Product Sequencing Kit (Amersham Life Sciences). HCV RNA was detected in 33 (66%) of the 50 serum samples. HCV RNA was detected in 19 (57.6%) of the corresponding 33 saliva samples. There was no correlation between oral health status or HIV seropositivity and the detection of HCV in saliva. However, subjects with HCV in their saliva were significantly more likely to complain of xerostomia (P < 0.05). Isolate genotypes were identified in paired serum and saliva of 15 intravenous drug users. HCV genotypes 1, 2, 3 and 6 were detected in both specimens. In seven cases, a differing HCV genotype was found in serum compared to the paired saliva specimen. The distributions of genotypes in serum and saliva were very different, with genotype 2a more common in saliva than serum (P < 0.005). These data suggest that in some cases the source of salivary HCV may not be serum transudation along the periodontal membrane or across damaged mucosa, and that an alternative local source, possibly the salivary glands themselves, should be considered.

Hepatitis C surveillance has been restricted owing to the lack of a sensitive antibody assay for saliva. The aim of our study was to develop and evaluate a screening assay for hepatitis C antibody in saliva specimens. Serum/saliva pairs were collected from 115 hepatitis C-positive patients. A modified hepatitis C antibody assay for saliva was developed and linked to testing carried out in the diagnostic laboratory. Correlation between the presence of antibody in serum and in saliva was poor (100% vs 85%). However, of 98 patients who were saliva antibody positive, 96 (98%) were also serum hepatitis C RNA positive and two (2%) were serum hepatitis C RNA negative. Hence, the correlation between a positive salivary antibody test and the serum hepatitis C RNA status of intravenous drug users suggests that this test could be used as a surrogate marker for hepatitis C viraemia in epidemiological studies.

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