Predictors of rabies exposure in travelers

Rabies is a fatal disease caused by contact with rabid animals. Worldwide, the WHO estimates that the total number of human rabies deaths in 2010 is as high as 61,000, with the fast majority occurring in Asia and Africa. For travelers from Western countries, the risk of contracting rabies is very low. The consequence of contracting rabies is, however, very serious: the fatality rate is (close to) 100%. Therefore, after an incident, timely provided post exposure prophylaxis (PEP) is needed. PEP consists of 5 vaccinations and anti rabies immunoglobulin (RIG) or, if the patient received PrEP (pre-exposure prophylaxis), 2 post exposure vaccinations. Yearly hundreds of Dutch travelers, potentially exposed to rabies abroad, consult a doctor for post-exposure prophylaxis (PEP) in the Netherlands. Consultations for possible rabies exposure need a careful and often time consuming assessment. Apart from financial costs, these assessments often take place in stressful circumstances, outside office-hours, as post-exposure prophylaxis (PEP) needs urgent administration. Furthermore, anti-rabies immunoglobulin (RIG) is an expensive and globally scarce product that should be used for those most at risk, i.e., the local population in endemic countries. Reduction of rabies exposure and reduction of the need for PEP –and especially RIG- contributes to a more efficient healthcare, in The Netherlands as well as in rabies endemic countries. The need for rabies PEP can be reduced in two ways. Firstly, many of the animal exposure accidents, especially with cats and monkeys, are easily preventable. Secondly, a pre-travel vaccination series (PrEP) of 3 vaccinations excludes the need for RIG after potential rabies exposure, and limits the PEP vaccination course to 2 injections. However, the vaccination costs of administering PrEP should be taken into account as well. This project aims to reduce potential rabies exposure and subsequent need for PEP, especially RIG, in Dutch travelers. Evidence-based guidelines including an interactive tool for individual advice on rabies prevention and PrEP will be developed through: 1) Identification of determinants of rabies exposure in travelers to rabies endemic areas, with focus on determinants (knowledge, risk perception and risk behavior) that may be influenced by pre-travel advice and determination of risk-groups. 2) Construction of a decision-tree based model for comparing per risk-group costs of different prevention scenarios, including PrEP and PEP, and define per risk-group the most cost-effective strategy. The project will consist of two parts. The first part consists of a retrospective case-control study and a prospective cohort study to identify determinants of possible rabies exposure in Dutch travelers. These two epidemiological studies are complementary towards each other and will result in traveler risk profiles. The second part consists of constructing a decision-tree based model to assess for each of the defined risk-groups the costs of several intervention strategies to prevent rabies in travelers and to define per risk-group the most cost-effective strategy using different perspectives. The model will be flexible, allowing for each defined risk group, the comparison of different rabies prevention and vaccination strategies within a particular risk group. Sensitivity analysis will be conducted on uncertain parameters, such as the assumed risk. Based on travelers determinants for possible rabies exposure (results part 1), combined with the costs of different scenarios for rabies prevention and the estimated incremental cost-effectiveness ratios (results part 2), a guideline –including an interactive tool- for individual advice on rabies prevention and exposure will be developed. In contrast to existing guidelines –that are based on single determinants of possible rabies exposure- in the new guidelines more determinants will be considered in connection with each other in order to define risk-groups and cost-effectiveness of PrEP for the various risk-groups. Ultimately, the study aims to reduce the number of potential rabies exposure and PEP indications, resulting in more effective travel advice, a lower burden of medical costs for PEP including consultations of public health specialists, better informed travelers, and less usage of scarce RIG in the Netherlands and abroad. The project group includes three types of organizations, including research, practice, and policy. The involvement of research organizations guarantees a thorough study design and analysis, and the involvement of travel clinics and public health services guarantees the participation of travelers. Finally, the involvement of the National Coordination Centre for Communicable Disease Control and the National Coordination Center for Travelers Health Advice guarantee the implementation of the results of the study in the national guidelines on rabies and travel advice.