Saliva can contain potentially infectious quantities of hepatitis C virus (HCV), particularly if an individual has a high HCV viral load and poor oral hygiene, according to research conducted amongst HCV-monoinfected individuals and presented to the 43^rd Interscience Conference on Antimicrobial Agents and Chemotherapy in Chicago on September 14 ^th.

On 21 consecutive days saliva samples were collected from twelve patients with HCV. Of the 248 samples collected, 52 (21%) tested positive for HCV RNA using ultra-sensitive testing equipment, which can detect the presence of HCV RNA as low as 43,000 copies/mL.

Five patients did not have detectable HCV in their saliva on any day during the study period, and none of the seven patients who shed HCV in their saliva did so every day (mean 7.30 days, range 1 – 13 days).

The strongest predictor of shedding was HCV serum viral load. No patient shed HCV in their saliva if they had a serum HCV viral load below 1 million copies/mL. Having an HCV viral load 1-log higher increased 40-fold the likelihood of the virus being shed in the saliva (p<.0001).

In the presence of a high serum viral load, the other major risk factors for having detectable HCV in saliva was gum disease. Patients were asked how many times a day they brushed their teeth and if bleeding occurred after brushing. Those individuals who brushed their teeth twice-daily were half as likely as those reporting once-daily brushing or less to have HCV present in saliva (p=0.2). In addition, gum bleeding was also found to be predictive of HCV being found in saliva (p=0.2). The investigators admit that these findings regarding oral hygiene are not statistically significant but are “provocative” and will be investigated further in a larger study.

“This study suggests that the saliva of individuals infected with hepatitis C may be infectious,” conclude the investigators, adding that “microscopic amounts of blood in the saliva due to gum disease may be responsible. People with HCV are cautioned not to share toothbrushes with other people in their household."

Reference

Wang C et al. Salivary shedding of HCV is associated with serum HCV RNA level and the presence of periodontal disease. 43^rd ICAAC, abstract V-773, Chicago, September 14 – 17^th, 2003.