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

Q Science (General);SF600 Veterinary Medicine

Sambo, Maganga ; Hampson, Katie

University:University of Glasgow

关键词: Rabies, vaccination, rabies control, accuracy, dog vaccination, rabies elimination, dog rabies, mass dog vaccinations, transects, dog,dog population growth, vaccination schedule, Vaccination of dogs.;   

Others  :  http://theses.gla.ac.uk/3662/25/2019SamboMagangaPhDc.pdf

来源: University of Glasgow

【 摘 要 】

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).