Scientific Opinion Of The Scientific Panel On Animal Health And Welfare On A Request From The Commission Regarding An "Assessment Of The Risk Of Rabies Introduction Into The Uk, Ireland, Sweden, Malta, As A Consequence Of Abandoning The Serological Test Measuring Protective Antibodies To Rabies." Efsa-Q-2006-014 Adopted By The Ahaw Panel On 11th Of December 2006

Although the rabies situation in Europe improved greatly during the last Century, the disease is still prevalent in wildlife in some EU member states and adjacent third countries. In areas where rabies occurs in wildlife a certain spill-over to domestic animals, including pets, may occur. It is therefore well justified that appropriate measures aimed at preventing pets from further spreading the disease are maintained as long as the disease persists in wildlife.Within EU the control of rabies in animals is based on a combination of national rules and Community legislation. The non-commercial movement of pets (dog, cat, ferrets) is governed by Regulation (EU) No 998/20031, establishing provisions for pet movement within the Community and from third countries into the EU. Article 6 of this Regulation provides that Ireland, UK, Sweden and Malta may maintain their national provisions for a transitional period of 5 years from the entry into force of this Regulation, i.e. until July 2008. These derogations consist of the requirement of an individual serological test for detection of neutralising rabies-antibodies and a waiting period before entry of pet animals into their territory.The Regulation further states that the derogations will be reviewed at the end of this transitory period of 5 years. To this end, the Commission has to submit to the European Parliament and to the Council, before the 1st of February 2007, a report on the need to maintain the serological test, and with appropriate proposals for determining the regime to be applied after this period. The report shall be based on the experience gained so far and on a risk analysis, following receipt of a scientific opinion of the European Food Safety Authority (EFSA).As a consequence, the Commission requested EFSA to issue a scientific opinion in order to assist in proposing appropriate amendments to the above Regulation. Specifically, the opinion should address to what extent abandoning the serological test could be envisaged without increasing the risk of introducing rabies and, if the need to maintain the serological test in certain circumstances is scientifically justified, what would be the appropriate regime/protocol giving equivalent assurances for the protection of these Member States against introduction of rabies.A number of countries have carried out independent rabies risk assessments in relation to pet movement. These assessments vary considerably in assumed control strategies and risk pathways and are therefore not directly comparable. They do, however, share most of the underlying parameter estimates used for modelling. To meet the terms of reference of the present assessment, it was judged necessary to develop risk pathways designed specifically to answer the questions raised, i.e. segregating the effect of testing from all other measures, using either established parameter estimates or modified according to available evidence.The risk of transmission of rabies by pet movement is related to moving an animal incubating disease. Pre-exposure vaccination of pets confers quick and almost complete protection to subsequent exposure by contact, e.g. bites. On the other hand, infection prior to vaccination cannot be controlled by immunisation but will require a quarantine and observation period covering the incubation period to be revealed. Previously, quarantine was implemented by physical isolation but with the advent of efficient vaccines, an "immunological quarantine" can be implemented with much less consequence for animal welfare.The unrestricted risk that a pet is incubating rabies at the time of primo-vaccination is equal to the prevalence of rabies-incubating pets in the population of origin. The prevalence can be estimated from the observed incidence of rabies in the population combined with an estimate of population size and the distribution of incubation times after natural infection. Following induction of protective immunity by vaccinating animal already incubating rabies will still develop clinical disease as a function of time after vaccination. Observing a vaccinated animal over a certain period will thus gradually reduce the risk ( termed type A in this opinion) that this animal incubates rabies, given that it has not developed clinical signs.Rabies vaccines are currently authorised on the basis of challenge tests in a target species and the measurement of protective levels of antibody. For monitoring the response to vaccination, the best available correlate with protection is to demonstrate that animals have achieved a serological titre of 0.5 IU/ml.As for any population of animals, a proportion may fail to mount an adequate serological response to vaccines and this may indicate that the individual animal may not be adequately protected against infection with the virus. If undetected, such animals may become infected after vaccination (termed type B risk in this opinion). The risk of the primo-vaccination with a single dose failing to induce an adequate serological response depends on the species, the age, the type of vaccine and the route and method of administration. Studies in published literature suggest that this risk can be effectively eliminated by administering a second vaccination at 4 to 6 weeks after the first, single vaccination thereby enhancing the chance that the desired antibody titre is achieved.However, such recommendations are not part of the currently approved immunisation schemes for most authorised products on the EU market where efficacy is ensured by rigorous challenge studies established by the European Pharmacopoeia.The overall risk reducing effect of applying a protocol including vaccination with or without testing and a specified waiting time has been modelled in a quantitative risk model. The major conclusions drawn from the study are:The primary means of protecting a pet from rabies in the population at risk is by vaccination. Inactivated rabies vaccines are highly efficient and induce rapid protective immunity that prevents infection and subsequent transmission of the disease.In quantitative terms, the type A risk constitutes by far the major risk. Therefore, a waiting time (defined as the time spent between vaccination and pet movement to the destined country), is the major effective measure to mitigate the risk of rabies introduction due to an animal being infected before primo-vaccination.The risk of infection following exposure during the waiting time (type B risk) depends on the protection induced by the vaccination in field conditions and becomes relatively more important as type A risk is reduced with extended waiting times (over 100 days). Serological testing can be used to identify seronegative pets and will therefore reduce this risk accordingly.Depending on the risk assessment model applied, a total risk reduction of 1.5 and 3.8, respectively, could be attributed to serological testing when the waiting time was 120 days. The same or an even better risk reduction can be obtained by replacing serological testing with a second vaccination 4 to 6 weeks after the first vaccination.For animals coming from countries with a negligible incidence of rabies, the best way to prevent rabies infection is simply by assuring adequate immunity after primo-vaccination before moving. In these countries, there is no rationale for including a waiting time beyond the time where protective immunity has been reached.The risk of transmitting rabies from populations where the annual incidence is below 1 in a million is considered negligible, even without applying a specific risk-mitigating protocol.Vaccination against rabies, using an authorised vaccine administered according to the approved vaccination schedule should remain the key requirement for pet movement between Member States. If further risk reduction is required, the protocol should include a waiting time following primo-vaccination and the length of waiting time should reflect the objective for risk reduction. The risk of having a certain proportion of pets vaccinated under field conditions that may not be fully protected can be reduced either by carrying out a serological test to measure antibodies or by administering a second injection of vaccine, provided that approved vaccination schedules are amended to include the option of administering a second injection where necessary.