Occupational lyssavirus risks and post-vaccination monitoring

In the UK, rabies pre-exposure vaccination involves a 3-dose course (DO, 7 & 28) and reinforcing doses at a 2-3 year intervals. This booster schedule had been implemented following scientific evidence indicating that a reduction in the previous regime interval of 3-5 years was warranted. The regime changes were particularly relevant to high risk groups that may encounter rabies virus. Those at known high risk of exposure to rabies and other Lyssaviruses include laboratory staff and a diverse group of animal handlers. Since the detection of EBLV-2 in the UK in four Daubenton's bats between 1996-2004 and a human case in 2002, those who now come into contact with bats are also considered at risk. Prior to 2002, data indicated that less than 50 % (n = 193) of all bat handlers had been vaccinated against rabies and 25 % of this group had exceeded the recommended booster interval. Following the human fatality, the vaccine became free to all UK bat handlers and all licensed and the majority of unlicensed bat handlers were vaccinated. Vaccinated laboratory workers are serologically monitored and boosted following a blood test of < 1.0 IU/ml of neutralising antibodies (FAVN-CVS). An analysis of laboratory staff (n = 25) indicated that 28 % (n = 7) maintained a suitable antibody level for greater than 5 years after their final boost, but 16 % (n = 4) had a titre of 1.0 IU/ml for < 12 months. Of the 25 individuals, 70 % required a booster in 2.5 years. In 2002, internal VLA policy was amended to increase antibody monitoring from 2 to 4 times per annum and to insist that all laboratory workers maintained a RABV titre of > 5.0 IU/ml for those in contact with non-RABV lyssaviruses in order to ensure that all individuals had antibody levels capable of neutralising the phylogroup I lyssaviruses.