Researchers in the United States have identified the first patient-to-patient transmission of hepatitis B virus (HBV) as a result of dental surgery, despite standard infection control procedures having been followed.
The case report has been published in the Journal of Infectious Diseases and the authors of both the paper and an accompanying editorial say the case reinforces the case for universal HBV childhood vaccination - carried out in the US since 1991.
The United Kingdom is one of the few developed countries that has not started vaccinating all children against HBV - although a government advisory group is currently reviewing the current policy of restricting vaccination to high risk groups only.
The US case involves a 60 year-old woman in New Mexico who went to her dentist for routine tooth extraction in October 2001. In February the following year she developed symptoms of acute HBV infection.
The woman was not sexually active, did not use intravenous drugs and had no known contacts with HBV-infected people. No problems with the surgery's infection control measures could be found. The dentist and all the staff tested negative for HBV.
This prompted the state health department to start an exhaustive investigation of the case.
Eventually the newly infected woman's virus was found to be identical to that of a 36 year-old woman who was infected in 1999 and had visited the same dentist on the same day to have three teeth extracted two and a half hours previously.
The researchers also tested 25 patients who had surgery at the dentist in the week after the 36 year-old HBV-infected woman. No other cases were found - possibly because 64% of them had been vaccinated against HBV.
The epidemiologists conclude that the transmission happened in the dental surgery, and that such cases seem to be rare (Redd 2007). The case reinforces the argument for universal HBV vaccination in the US and meticulous maintenance of infection control for all patients in dental settings, they conclude.
But in the accompanying editorial two infectious diseases specialists question whether such transmission can really be said to be rare (Allos and Schaffner).
They say: "We suggest the current burden of healthcare acquired [HBV] is largely unknown because only modest efforts have been made to identify such cases and quantity the risk."
They stress the huge efforts made by the New Mexico State Department of Health to identify that the route of transmission was unusual and say: "If no traditional risk factors are found the investigation usually stops."
The UK government's Joint Committee on Vaccination and Immunisation is currently reviewing the evidence for vaccinating all children against HBV.
But the most recent minutes - from a meeting in October last year - suggest the committee might recommend vaccinating only children of families in which one or both parents come from countries where HBV is common (JCVI 2006).