ABSTRACT
Background Dog-mediated rabies is endemic across Africa causing thousands of human deaths annually. A One Health approach to rabies is advocated, comprising emergency post-exposure vaccination of bite victims and mass dog vaccination to break the transmission cycle. However, the impacts and cost-effectiveness of these components are difficult to disentangle. Methods We combined contact tracing with whole-genome sequencing to track rabies transmission in the animal reservoir and spillover risk to humans from 2010-2020, investigating how the components of a One Health approach reduced the disease burden and eliminated rabies from Pemba island, Tanzania. With the resulting high-resolution spatiotemporal and genomic data we inferred transmission chains, estimated case detection and quantified the public health burden to evaluate these interventions. Results We resolved five transmission chains co-circulating on Pemba from 2010 that were all eliminated by May 2014. During this period, rabid dogs, human rabies exposures and deaths all progressively declined following initiation and improved implementation of annual islandwide dog vaccination. We identified two introductions to Pemba in late 2016 that seeded re-emergence after dog vaccination had lapsed. The ensuing outbreak was eliminated in October 2018 through reinstated islandwide dog vaccination. While post-exposure vaccines were highly cost-effective ($405 per death averted), their accessibility was limited and only dog vaccination interrupted transmission. A combined One Health approach rapidly eliminated rabies, was highly cost-effective ($1865 per death averted) and saved 20-120 families from rabid dog bites annually. Conclusions A One Health approach underpinned by dog vaccination is an efficient, cost-effective, equitable and feasible approach to rabies elimination, but needs scaling up across connected populations to sustain the benefits of elimination, as seen on Pemba, and for similar progress to be achieved elsewhere. Funding Wellcome [207569/Z/17/Z, 095787/Z/11/Z, 103270/Z/13/Z], the UBS Optimus Foundation, and the DELTAS Africa Initiative [Afrique One-ASPIRE/DEL-15-008] comprising a donor consortium of the African Academy of Sciences (AAS), Alliance for Accelerating Excellence in Science in Africa (AESA), the New Partnership for Africa’s Development Planning and Coordinating (NEPAD) Agency, Wellcome [107753/A/15/Z] and the UK government. The rabies elimination demonstration project from 2010-2015 was supported by the Bill & Melinda Gates Foundation (OPP49679) and whole-genome sequencing was partially supported at APHA by Defra grant SE0421.
ABSTRACT
Background: : Every year at least 59,000 people are estimated to die from rabies and more than 10 million are treated with post-exposure prophylaxis (PEP). Over 99% of human rabies deaths occur in developing countries due to bites from domestic dogs. Large-scale mass dog vaccination programs can control dog rabies and, if sustained, can eliminate dog-mediated rabies. However, there has been very little investment in mass dog vaccination against rabies in sub-Saharan Africa, largely due to limited human and financial resources. To overcome this limitation, we piloted the delivery of synchronized dog vaccinations using a temporary workforce of university students. Fifty university students from Sokoine University of Agriculture and Muhimbili University of Health and Allied Sciences were selected to deliver dog vaccinations throughout the Kisarawe district in Tanzania in May 2021. We analysed the vaccination coverage achieved and the cost per dog vaccinated in delivering dog vaccinations using the university students compared to the traditional delivery. Results: : A total of 1,457 dogs and 242 cats were vaccinated across 48 villages in the Kisarawe district of Tanzania over the course of five days. The overall cost in delivering mass dog vaccinations was estimated at US$ 28,990 equating to approximately US$19.90 per vaccinated dog. Post-vaccination transects were conducted in all 48 villages where dog vaccinations were implemented, counting 387 dogs. Of these, 54% dogs (N=210) were vaccinated against rabies, 67% (N=258) were free-roaming dogs and 72% of dogs encountered were adult (N=277). The overall district-level mean vaccination coverage was estimated to be 54.3% (CI 49.3% - 59.6). Conclusions: : We demonstrated that using university students as a One Health workforce is effective in accelerating the countries’ efforts to meet the global target of eliminating dog-mediated human rabies by 2030.