Abstract
Despite perceived challenges to controlling an infectious disease in wildlife, oral rabies vaccination (ORV) of foxes has proved a remarkably successful tool and a prime example of a sophisticated strategy to eliminate disease from wildlife reservoirs. During the past three decades, the implementation of ORV programmes in 24 countries has led to the elimination of fox-mediated rabies from vast areas of Western and Central Europe. In this study, we evaluated the efficiency of 22 European ORV programmes between 1978 and 2010. During this period an area of almost 1.9 million km² was targeted at least once with vaccine baits, with control taking between 5 and 26 years depending upon the country. We examined factors influencing effort required both to control and eliminate fox rabies as well as cost-related issues of these programmes. The proportion of land area ever affected by rabies and an index capturing the size and overlap of successive ORV campaigns were identified as factors having statistically significant effects on the number of campaigns required to both control and eliminate rabies. Repeat comprehensive campaigns that are wholly overlapping much more rapidly eliminate infection and are less costly in the long term. Disproportionally greater effort is required in the final phase of an ORV programme, with a median of 11 additional campaigns required to eliminate disease once incidence has been reduced by 90 per cent. If successive ORV campaigns span the entire affected area, rabies will be eliminated more rapidly than if campaigns are implemented in a less comprehensive manner, therefore reducing ORV expenditure in the longer term. These findings should help improve the planning and implementation of ORV programmes, and facilitate future decision-making by veterinary authorities and policy-makers.
Highlights
Vaccination programmes are one of the most effective means of controlling infectious diseases [1]
We considered the following variables as potential factors influencing the baseline hazard of effort required to control and eliminate fox rabies from a country: the size of the country; the area and proportion of the territory that was ever vaccinated; the length of borders to neighbouring rabies-infected areas; initial rabies incidence in the year prior to the implementation of oral rabies vaccination (ORV), expressed both as the number of detected cases and the number of detected cases per square kilometre; years of ORV experience prior to each country starting an ORV programme; and an index that captures the contiguity and overlap of consecutive ORV campaigns carried out in a country ([41]; table 2)
Since 1978 the overall size of the area under vaccination in Europe steadily increased to 614 773 km2 in 1996 as countries in Western and Central Europe began to implement ORV programmes
Summary
Vaccination programmes are one of the most effective means of controlling infectious diseases [1]. Wildlife diseases that pose a threat to public health, livestock production or conservation are less likely to be considered as candidates for vaccination programmes owing to the difficulty and expense in the mass delivery of vaccines to wild animal populations. License http://creativecommons.org/licenses/by/3.0/, which permits unrestricted use, provided the original author and source are credited. With the development of oral vaccines and bait delivery systems, the elimination of diseases circulating in wildlife populations has become a tantalizing possibility. The pre-eminent example of vaccination of wildlife populations is the large-scale oral vaccination programmes that have eliminated fox rabies from Western Europe and greatly reduced incidence in Central Europe [5]. We focus on the effectiveness of these programmes, and the factors underlying the critical transition from disease control to the ultimate goal of disease elimination
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