Boyd Orr Centre for Population and Ecosystem Health; Institute of Biodiversity, Animal Health and Comparative Medicine; College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
Rabies is a fatal zoonosis that can infect and be transmitted from all mammal species, but the vast majority of human deaths worldwide result from the bite of rabid dogs. Although rabies has been successfully controlled in many parts of the world, it is estimated that at least 55,000 people still die every year from canine-mediated rabies, mostly children in Asia and Africa, where canine rabies remains endemic (Knobel et al. 2005; WHO 2013). Rabies is a disease of poverty, affecting people who live in marginalized communities with little access to health or veterinary services. In these communities, rabies has a major psychological impact, traumatising those who witness a case, and causing profound anxiety for those needing the costly post-exposure prophylaxis after the bite of a suspected rabid dog. The disease also causes substantial livestock losses, which are only recently quantified (WHO 2013), and has severe impacts on animal welfare. These arise not only because of the direct impacts of the rabies on affected animals, but also because inhumane measures are sometimes introduced to control dog populations as a response to the rabies problem.
Although human rabies remains a serious public health problem in Africa and Asia, the disease is entirely preventable through prompt post-exposure prophylaxis (PEP) of people who have been bitten by rabid animals, as well as control of rabies in animal reservoir populations. Over the past decade, there has been growing awareness of the epidemiological and logistic feasibility of global canine rabies elimination through mass vaccination of domestic dog reservoirs (Rupprecht et al. 2009; Lembo et al. 2010), even in areas that have abundant and diverse wildlife populations (Lembo et al. 2009). Approaches that focus on mass dog vaccination are also likely to be more cost-effective at preventing human rabies deaths than reliance on human PEP alone because of the high costs of PEP (involving administration of immunoglobulin and a multidose course of intramuscular or intradermal vaccination) (Zinsstag et al. 2009; Fitzpatrick et al. 2014). In addition, an emphasis on mass dog vaccination protects people in the most vulnerable communities who, when bitten by rabid dogs, face difficulties accessing health facilities and are often unable to receive PEP in sufficient time (within 24 hours of the bite) to ensure protection against rabies.
In recognition of the human and animal health burden of rabies and the feasibility of rabies control, there have been growing calls for the global elimination of canine rabies, with the development of several initiatives involving international human and animal health agencies (PAHO, WHO, OIE and FAO), international rabies partnerships (Partners for Rabies Prevention, Global Alliance for Rabies Control, GARC), professional bodies (e.g., WSAVA) and donor organizations. These include: (a) a series of joint resolutions demonstrating commitment towards the global elimination of canine rabies by WHO, OIE and FAO, together with partner organizations (such as WSAVA); (b) advocacy campaigns initiated by the Global Alliance for Rabies Control, including World Rabies Day (Hanlon et al. 2008); (c) an online 'blueprint' for control and elimination of canine rabies developed by GARC (Lembo et al. 2012) and guidelines for humane control of rabies through mass dog vaccination developed by the World Society for the Protection of Animals (WSPA); (d) development of a 'step-wise' approach for guiding national and regional rabies control and elimination strategies initiated by FAO-GARC (FAO 2013); (e) rabies elimination demonstration projects implemented in Asia (e.g., Philippines, Bali, India), Africa (e.g., South Africa, Chad, Tanzania), and Eurasia (e.g., Turkey); (f) establishment of dog rabies vaccine banks by OIE.
The most notable successes in rabies control in recent decades have come from Latin America, where the strong political and technical commitment of countries to rabies control and elimination started with a regional program coordinated by the Pan American Health Organization (PAHO) in the 1980s, including implementation of mass dog vaccination campaigns and integrated surveillance across human health and veterinary sectors (Vigilato et al. 2013). In these regions, it has been recognized that mass canine vaccination campaigns are one of the most important actions for rabies control and require wide inter-sectoral involvement from veterinary services, communities, and education sectors in the planning, promotion, implementation and evaluation of campaigns (Vigilato et al. 2013). As a result, human deaths from canine rabies in Latin America are now vanishingly rare, with elimination targeted for 2015 (WHO 2012). However, the elimination program is now at a critical end-stage, and intensive surveillance and vaccination efforts need to be sustained to prevent resurgence of rabies from the remaining foci of infection.
In Asia, national strategies for human rabies prevention have generally focused on improved access to PEP or reducing the number of free-roaming dogs, with less attention given to mass dog vaccination. While increasing access to PEP has successfully reduced the number of human rabies deaths, this has come at a very high economic cost (WHO 2013), and costs will continue to escalate unless attention is given to control in the domestic dog reservoir. While dog population control has an intuitive appeal for canine rabies control, a large body of empirical and theoretical evidence suggests that this approach is unlikely to be effective. Critically, the value of the basic reproduction number, R0 , of canine rabies (which determines how the disease spreads through a population) lies between 1–2 in all dog populations, irrespective of density and demographic characteristics (Hampson et al. 2009; Townsend et al. 2013). Hence, reducing the density of dogs is unlikely to affect rabies transmission. Furthermore, indiscriminate killing or removal of dogs can potentially exacerbate disease spread as people bring in replacement dogs. In contrast, mass vaccination of dogs provides a feasible, acceptable and effective approach. The consistently low value of R0 indicates that canine rabies elimination can be achieved through vaccination campaigns that reach 70% of the dog population (Hampson et al. 2009), and this target is feasible in most areas of Africa, Asia and Latin America, despite misperceptions of large ownerless or 'stray' dog populations (Lembo et al. 2010; Davlin, Vonville 2012).
As with Latin America, examples of effective dog rabies control programs in Asia demonstrate that political support and community engagement are critical components of successful rabies control. For example, in the Philippines (Bohol), successful rabies control programs have involved mobilisation of thousands of community volunteers in mass dog vaccination campaigns, dissemination of rabies educational materials, and introduction of community-level rabies surveillance measures (Lapiz et al. 2012).
Although few national programs have yet to be implemented in Africa, momentum is building towards a strategy for canine rabies elimination in Africa, underpinned by the growing evidence base from research studies and rabies campaigns in Kwa Zulu Natal (South Africa), N'Djamena (Chad), and Serengeti (Tanzania). This strategy aims to build on the principle of a step-wise approach (FAO 2013), with achievable objectives proposed at each stage to build the infrastructure, expertise and confidence in the operational feasibility of dog rabies control. The aim is to focus activities first in selected areas, where expertise and rabies 'champions' are currently active, and to link these hubs of activity within regional networks to achieve large-scale, contiguous vaccination coverage. As is the case in other regions, community engagement in Africa is also critical, and new approaches being explored for community-directed implementation of dog vaccination campaigns, for example, involving community-based health workers already engaged in national programs for control of neglected tropical diseases (NTDs), such as schistosomiasis, lymphatic filariasis and soil-transmitted helminths.
Inevitably, the question will arise as to the cost of achieving global canine rabies elimination. In principle, mass dog vaccination can result in substantial savings to the public health sector (through reduced use of costly PEP), and these savings could be used to sustain dog vaccination campaigns to achieve canine rabies elimination - an exemplar of the benefits of a One Health approach. However, integrated management of budgets across human health and veterinary sectors remains a challenge and new approaches continue to be explored, including development of public-private partnerships and more integrated models of vaccine delivery.
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