Measuring, monitoring and improving mass dog vaccination programmes to control and eliminate rabies

Rabies is an acute viral infection which causes horrifying neurological symptoms that inevitably result in death. 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 90% of human rabies deaths occur in Asia and Africa following bites from domestic dogs. Although human rabies deaths are 100% preventable through the delivery of prompt PEP to bite victims following a bite, PEP is not accessible to many poor rural victims, most of whom subsist on less than US$1.25/day. Empirical and theoretical evidence shows that mass dog vaccination that reaches 70% of susceptible dog population can interrupt the transmission cycle. Rabies has been eliminated from industrialized countries through mass dog vaccination, and the continent-wide elimination of canine rabies from the Americas is now within reach. In contrast, no effective large-scale control of dog rabies has been achieved in Africa and information is still needed to optimise and sustain dog vaccination programmes. The aim of this thesis was to evaluate the rabies control programme in Tanzania. This thesis is presented as a series of three standalone chapters (Chapters 2-4) that are introduced and then summarised by a general introduction (Chapter 1) and a general discussion (Chapter 5) respectively. Achieving high coverage is the most important aim of any vaccination programme; however, assessing the vaccination coverage achieved is often neglected in rabies endemic countries. In Chapter 2, I compare three methods of measuring vaccination coverage (post-vaccination transects, school-based surveys, and household surveys) across 28 districts in different settings in southeast Tanzania and Pemba island in order to determine which is most precise method. These approaches were explored in detail in a single district in northwest Tanzania (Serengeti), where their performance in producing precise estimates of coverage was compared with a complete dog population census that also recorded dog vaccination status. Our analysis found that transect studies (counting vaccinated and unvaccinated dogs) immediately after the campaign is cheap, quick, and provides precise estimates. Therefore, transects were considered more appropriate for routine monitoring of mass vaccination campaigns than household or school-based surveys. In Chapter 3, I used data from Chapter 2 together with human population census data from Tanzanian Bureau of Statistics to develop a model for estimation of the size of dog populations in Tanzania. Knowledge of the size of the dog population is necessary to adequately plan and achieve the target of vaccinating 70% of susceptible dogs. I demonstrate that estimating dog population size using transect data gave more precise results than either household or school-based surveys. Therefore, transect data were used to develop a predictive model for estimating dog populations in districts lacking transect data. Using this model, I predict a dog population of 2.32 (95% CI 1.57,3.12) million in Tanzania and an average human to dog ratio of 20.7:1. In Chapter 4, I evaluate the implementation and performance of large-scale dog vaccination campaigns against rabies in Tanzania. For an effective rabies control and elimination, it is necessary to conduct vaccination campaigns in every village/street (completeness), achieve coverage of 70% (coverage) and return for dog vaccination within one year (timeliness). Therefore, in this Chapter 4, I assessed vaccination campaigns in terms of completeness, coverage and timeliness; I also investigated factors associated with and potentially causing success or failure of mass dog vaccinations, in terms of completeness and coverage. Overall, this study shows that Tanzania experienced notable challenges in the delivery of mass dog vaccinations. For example, although vaccination completeness improved over time, until the last two rounds of vaccinations, only 25% of districts had 100% campaigns completeness. Additionally, very few districts (27-36% of the study districts) achieved the recommended vaccination coverage of 70% between third and fifth round of vaccinations. Vaccination interval was planned to be annually but vaccinations delayed to more than two years, as a result, vaccinations were conducted in pulsed approach (not annually)

Epidemiological dynamics of rabies in Tanzania and its impacts on local communities.

Rabies is a fatal viral zoonotic infection caused by a Lyssavirus. Rabies exerts a major public health and economic burden; it is responsible for at least 55,000 deaths worldwide, predominantly in Africa and Asia. More than 90% of rabies deaths are caused by domestic dogs. Global expenditure on rabies prevention and control exceeds US$500 million per annum. Although human rabies is 100 Effective implementation of sustainable rabies control and prevention programs, involves full participation of individuals, veterinary and medical services. Veterinary services must control rabies transmission through mass dog vaccination campaigns because human deaths are caused by epidemics in domestic dogs, medical services must provide PEP to prevent disease in exposed individuals and exposed individuals must seek PEP and dog owners must take their dogs to be vaccinated. This thesis focuses on factors affecting individuals and medical services. This thesis examines challenges in the control and prevention of rabies in sub-Saharan Africa. Firstly, to address these challenges, we developed an analytical framework to portray the influence of individual and institutional factors within both the veterinary and medical services, in controlling and preventing rabies. The research carried out in chapters two and three investigate different aspects of this framework. Specifically in Chapter 2, we conducted a knowledge, attitude and practice (KAP) survey in seven districts covering southern, central and northern Tanzania. We used the collected data to investigate factors that influence knowledge of rabies and how knowledge of rabies influences attitudes and practice in control and prevention of rabies. Our findings show that knowledge about rabies in Tanzania is limited. However, we found an indication that those who were more knowledgeable of rabies claimed to practise better rabies control and prevention. In Chapter 3, we collected information using contact tracing and questionnaires to evaluate the burden of rabies and its impacts on local communities. The study demonstrated that rabies is a substantial economic concern to bite victims. A bite victim in Tanzania would be required to spend over US$70 to complete WHO recommended PEP schedules. The costs of PEP disproportionately affect bite victims from rural areas where PEP doses are often not available. Families reported spending family allowances, borrowing money and or selling crops or livestock to pay for PEP. Fewer than 10% of families paid for PEP from their salary compared to 15% of patients from urban areas. Otherwise, patients depended on external financial sources such as contributions from relatives or friends or decided not to seek PEP because of the high costs involved. High PEP costs also affected compliance with PEP schedules. The probability of obtaining the first dose of PEP was about 70%, declined slightly for the second and third doses but declined dramatically for the fourth and fifth doses. We also found that 15% of bite victims who did not receive any PEP went on to develop rabies. The costs of PEP were 2 times higher than costs previously reported from Africa. In Chapter 4 we discuss our overall results and conclude that interventions to control and prevent rabies require multi-sector commitment of all key stakeholders

The Burden of Rabies in Tanzania and Its Impact on Local\ud Communities

Rabies remains a major public health threat in many parts of the world and is responsible for an estimated 55,000 human deaths annually. The burden of rabies is estimated to be around US$20 million in Africa, with the highest financial expenditure being the cost of post-exposure prophylaxis (PEP). However, these calculations may be substantial underestimates because the costs to households of coping with endemic rabies have not been investigated. We therefore aimed to estimate the household costs, health-seeking behaviour, coping strategies, and outcomes of exposure to rabies in rural and urban communities in Tanzania. Extensive investigative interviews were used to estimate the incidence of human deaths and bite exposures. Questionnaires with bite victims and their families were used to investigate health-seeking behaviour and costs (medical and non-medical costs) associated with exposure to rabies. We calculated that an average patient in rural Tanzania, where most people live on less than US$1 per day, would need to spend over US$100 to complete WHO recommended PEP schedules. High costs and frequent shortages of PEP led to poor compliance with PEP regimens, delays in presentation to health facilities, and increased risk of death. The true costs of obtaining PEP were twice as high as those previously reported from Africa and should be considered in re-evaluations of the burden of rabies

Knowledge, Attitudes and Practices (KAP) about rabies prevention and control: a community survey in Tanzania

BACKGROUND: Despite being entirely preventable,canine rabies still kills 55,000 people/year in developing countries. Information about local beliefs and practices can identify knowledge gaps that may affect prevention practices and lead to unnecessary deaths. METHODOLOGY/PRINCIPAL FINDINGS: We investigated knowledge, attitudes and practices related to rabies and its prevention and control amongst a cross-section of households (n = 5,141)in urban and rural areas of central, southern and northern Tanzania. Over 17% of respondents owned domestic dogs (average of 2.3 dogs/household), >95% had heard about rabies, and >80% knew that rabies is transmitted through dog bites. People who (1)had greater education,(2)originated from areas with a history of rabies interventions,(3)had experienced exposure by a suspect rabid animal,(4)were male and(5)owned dogs were more likely to have greater knowledge about the disease. Around 80% of respondents would seek hospital treatment after a suspect bite, but only 5% were aware of the need for prompt wound cleansing after a bite. Although >65% of respondents knew of dog vaccination as a means to control rabies, only 51% vaccinated their dogs. Determinants of dog vaccination included(1)being a male-headed household,(2)presence of children,(3)low economic status,(4)residing in urban areas,(5)owning livestock,(6)originating from areas with rabies interventions and(7)having purchased a dog. The majority of dog-owning respondents were willing to contribute no more than US$0.31 towards veterinary services. CONCLUSIONS/SIGNIFICANCE: We identified important knowledge gaps related to, and factors influencing the prevention and control of rabies in Tanzania. Increasing knowledge regarding wound washing, seeking post-exposure prophylaxis and the need to vaccinate dogs are likely to result in more effective prevention of rabies; however, greater engagement of the veterinary and medical sectors is also needed to ensure the availability of preventative services

Estimating the size of dog populations in Tanzania to inform rabies control

Estimates of dog population sizes are a prerequisite for delivering effective canine rabies control. However, dog population sizes are generally unknown in most rabies-endemic areas. Several approaches have been used to estimate dog populations but without rigorous evaluation. We compare post-vaccination transects, household surveys, and school-based surveys to determine which most precisely estimates dog population sizes. These methods were implemented across 28 districts in southeast Tanzania, in conjunction with mass dog vaccinations, covering a range of settings, livelihoods, and religious backgrounds. Transects were the most precise method, revealing highly variable patterns of dog ownership, with human/dog ratios ranging from 12.4:1 to 181.3:1 across districts. Both household and school-based surveys generated imprecise and, sometimes, inaccurate estimates, due to small sample sizes in relation to the heterogeneity in patterns of dog ownership. Transect data were subsequently used to develop a predictive model for estimating dog populations in districts lacking transect data. We predicted a dog population of 2,316,000 (95% CI 1,573,000–3,122,000) in Tanzania and an average human/dog ratio of 20.7:1. Our modelling approach has the potential to be applied to predicting dog population sizes in other areas where mass dog vaccinations are planned, given census and livelihood data. Furthermore, we recommend post-vaccination transects as a rapid and effective method to refine dog population estimates across large geographic areas and to guide dog vaccination programmes in settings with mostly free roaming dog populations

Public health at the margins: local realities and the control of neglected tropical diseases in Eastern Africa

Neglected Tropical Diseases (NTDs) are both causes and manifestations of poverty in developing countries. Recent advocacy efforts have increased the profile of NTDs, and led to bold new control and elimination targets set for 2020 by the World Health Organisation. However there are multifaceted challenges in effectively implementing NTD interventions in resource-poor contexts that need to be understood and engaged. While there is a growing call by researchers and international agencies for a science of global health delivery to understand these complexities, the exact nature of this science remains contested. This thesis contributes to these debates by advancing a critical social science perspective on the factors that mediate intervention effectiveness for NTD control. Grounded in a social constructivist approach using mixed methods, it critiques prevailing orthodoxies by unpacking the nature, processes and outcomes of three large-scale NTD prevention programmes in Eastern Africa. Focused on different diseases, these case studies represent different types of intervention approaches: top-down, participatory and public-private partnership. The thesis traces the social, technical and environmental processes that mediate the delivery, adoption and use of particular health technologies, such as pit latrines, insecticides and vaccination. Together, these case studies reveal surprisingly similar reasons for why many interventions do not perform according to expectations. Despite new approaches that claim to overcome stereotypical challenges of top-down planning, narrow technocratic perspectives continue to play a defining role in maintaining disjunctions between global aspirations, local realities and intervention outcomes. New perspectives and changes in orientation are needed that emphasise flexibility, learning and adaptability to local contexts. Towards this end, the thesis outlines a conceptual framework based on a comparative analysis of the case studies that highlights five interrelated domains where effectiveness is determined: geographical/livelihood variation, local agency, incentives, the socio-materiality of technology and planning/governance. I argue that addressing the shortcomings of contemporary interventions requires that programme planners actively engage these domains by seeking to “order complexity.” Greater integration of social science perspectives into the management of NTD programmes would provide significant benefit. In these ways, the thesis contributes to wider debates about the nature of global health interventions and the influence of local contexts in mediating efforts to improve the health and wellbeing of the world’s poor and marginalised

Elucidating the phylodynamics of endemic rabies virus in eastern Africa using whole-genome sequencing

Many of the pathogens perceived to pose the greatest risk to humans are viral zoonoses, responsible for a range of emerging and endemic infectious diseases. Phylogeography is a useful tool to understand the processes that give rise to spatial patterns and drive dynamics in virus populations. Increasingly, whole-genome information is being used to uncover these patterns, but the limits of phylogenetic resolution that can be achieved with this are unclear. Here, whole-genome variation was used to uncover fine-scale population structure in endemic canine rabies virus circulating in Tanzania. This is the first whole-genome population study of rabies virus and the first comprehensive phylogenetic analysis of rabies virus in East Africa, providing important insights into rabies transmission in an endemic system. In addition, sub-continental scale patterns of population structure were identified using partial gene data and used to determine population structure at larger spatial scales in Africa. While rabies virus has a defined spatial structure at large scales, increasingly frequent levels of admixture were observed at regional and local levels. Discrete phylogeographic analysis revealed long-distance dispersal within Tanzania, which could be attributed to human-mediated movement, and we found evidence of multiple persistent, co-circulating lineages at a very local scale in a single district, despite on-going mass dog vaccination campaigns. This may reflect the wider endemic circulation of these lineages over several decades alongside increased admixture due to human-mediated introductions. These data indicate that successful rabies control in Tanzania could be established at a national level, since most dispersal appears to be restricted within the confines of country borders but some coordination with neighbouring countries may be required to limit transboundary movements. Evidence of complex patterns of rabies circulation within Tanzania necessitates the use of whole-genome sequencing to delineate finer scale population structure that can that can guide interventions, such as the spatial scale and design of dog vaccination campaigns and dog movement controls to achieve and maintain freedom from disease

Tackling barriers to collective action for effective vaccination campaigns: rabies in rural Africa as an example

Vaccine-based protection in populations that are vulnerable to infectious diseases represents a public good, whose successful attainment requires collective action. We investigated participation in mass domestic dog vaccination against dog-mediated human rabies endemic in Tanzania as a prototypical example of these issues. We employed advertising interventions, text messaging and/or engagement through community leaders, as well as operational adjustments to increase the saliency of rabies risks and reduce barriers to participation in vaccination campaigns. Neither advertising strategies were effective on their own, however, when taken together, the two advertising strategies substantially improved vaccination coverage. Operational interventions, such as increasing vaccination stations and extending time windows of delivery, greatly enhanced participation. Our experimental and theoretical findings highlight the importance of both salience and context: sparking successful collective action requires decision-making bodies to understand and respond to the challenges encountered by intended beneficiaries in their local contexts

Comparing methods of assessing dog rabies vaccination coverage in rural and urban communities in Tanzania

Rabies can be eliminated by achieving comprehensive coverage of 70% of domestic dogs during annual mass vaccination campaigns. Estimates of vaccination coverage are, therefore, required to evaluate and manage mass dog vaccination programs; however, there is no specific guidance for the most accurate and efficient methods for estimating coverage in different settings. Here, we compare post-vaccination transects, school-based surveys, and household surveys across 28 districts in southeast Tanzania and Pemba island covering rural, urban, coastal and inland settings, and a range of different livelihoods and religious backgrounds. These approaches were explored in detail in a single district in northwest Tanzania (Serengeti), where their performance was compared with a complete dog population census that also recorded dog vaccination status. Post-vaccination transects involved counting marked (vaccinated) and unmarked (unvaccinated) dogs immediately after campaigns in 2,155 villages (24,721 dogs counted). School-based surveys were administered to 8,587 primary school pupils each representing a unique household, in 119 randomly selected schools approximately 2 months after campaigns. Household surveys were conducted in 160 randomly selected villages (4,488 households) in July/August 2011. Costs to implement these coverage assessments were $12.01,$66.12, and $155.70 per village for post-vaccination transects, school-based, and household surveys, respectively. Simulations were performed to assess the effect of sampling on the precision of coverage estimation. The sampling effort required to obtain reasonably precise estimates of coverage from household surveys is generally very high and probably prohibitively expensive for routine monitoring across large areas, particularly in communities with high human to dog ratios. School-based surveys partially overcame sampling constraints, however, were also costly to obtain reasonably precise estimates of coverage. Post-vaccination transects provided precise and timely estimates of community-level coverage that could be used to troubleshoot the performance of campaigns across large areas. However, transects typically overestimated coverage by around 10%, which therefore needs consideration when evaluating the impacts of campaigns. We discuss the advantages and disadvantages of these different methods and make recommendations for how vaccination campaigns can be better monitored and managed at different stages of rabies control and elimination programs

Use of lay vaccinators in animal vaccination programmes: a scoping review

Background: The human resource gap in veterinary sectors, particularly in low-income countries, imposes limitations on the delivery of animal healthcare in hard-to-reach populations. Lay animal health workers have been deployed in these settings to fill the gap though there are mixed views about the benefits of doing this and whether they can deliver services safely. We mapped evidence on the nature and extent of roles assigned to lay animal vaccinators, and identified lessons useful for their future deployment. Methodology/Principal findings: Following the PRISMA Extension for Scoping Reviews guidelines, we searched seven bibliographic databases for articles published between 1980 and 2021, with the search terms lay OR community-based OR volunteer AND "animal health worker" OR vaccinator*, and applied an a priori exclusion criteria to select studies. From 30 identified studies, lay vaccinators were used by non-government developmental (n = 12, 40%), research (n = 10, 33%) and government (n = 5, 17%) programmes to vaccinate domestic animals. The main reason for using lay vaccinators was to provide access to animal vaccination in the absence of professional veterinarians (n = 12, 40%). Reported positive outcomes of programmes included increased flock and herd sizes and farmer knowledge of best practice (n = 13, 43%); decreased disease transmission, outbreaks and mortality (n = 11, 37%); higher vaccination coverage (10, 33%); non-inferior seroconversion and birth rates among vaccinated herds (n = 3, 10%). The most frequently reported facilitating factor of lay vaccinator programmes was community participation (n = 14, 47%), whilst opposition from professional veterinarians (n = 8, 27%), stakeholders seeking financial gains to detriment of programmes goals (n = 8, 27%) and programming issues (n = 8, 27%) were the most frequently reported barriers. No study reported on cost-effectiveness and we found no record from a low and middle-income country of lay vaccinator programmes being integrated into national veterinary services. Conclusion: Although the majority of included studies reported more benefits and positive perceptions of lay vaccinator programmes than problems and challenges, regularization will ensure the programmes can be designed and implemented to meet the needs of all stakeholders