A bioeconomic model for the optimization of local canine rabies control

Cost-effectiveness of One Health interventions for rabies elimination: a systematic review

The 'One Health' (OH) approach is the most promising idea in realising the global goal of eliminating canine-mediated human rabies by 2030. However, taking an OH approach to rabies elimination can mean many different things to different people. We conducted a systematic review scrutinizing economic evaluations (EEs) retrieved from MEDLINE OVID, Embase OVID, Global Health OVID, CINAHL EBSCO and ECONLIT EBSCO that used the OH approach with the intent of identifying cost-effective sets of interventions that can be combined to implement an optimal OH-based rabies elimination program and highlight key gaps in the knowledge base. Our review suggests that an optimal OH program to tackle rabies should incorporate mass dog vaccination and integrated bite case management in combination with efficient use of post-exposure prophylaxis along with a shift to a 1-week abbreviated intradermal rabies vaccine regimen in humans. We recommend that future EEs of OH interventions for rabies elimination should be performed alongside implementation research to ensure proposed interventions are feasible and adopt a wider societal perspective taking into account costs and outcomes across both the human health and animal welfare sectors. The systematic review has been registered with PROSPERO.

Evaluation of contingency actions to control the spread of raccoon rabies in Ohio and Virginia

The raccoon (Procyon lotor) variant of the rabies virus (RRV) is enzootic in the eastern United States and oral rabies vaccination (ORV) is the primary strategy to prevent and control landscape spread. Breaches of ORV management zones occasionally occur, and emergency "contingency" actions may be implemented to enhance local control. Contingency actions are an integral part of landscape-scale wildlife rabies management but can be very costly and routinely involve enhanced rabies surveillance (ERS) around the index case. We investigated two contingency actions in Ohio (2017-2019 and 2018-2021) and one in Virginia (2017-2019) using a dynamic, multi-method occupancy approach to examine relationships between specific management actions and RRV occurrence, including whether ERS was sufficient around the index case. The RRV occupancy was assessed seasonally at 100-km2 grids and we examined relationships across three spatial scales (regional management zone, RRV free regions, and local contingency areas). The location of a grid relative to the ORV management zone was the strongest predictor of RRV occupancy at the regional scale. In RRV free regions, the neighbor effect and temporal variability were most important in influencing RRV occupancy. Parenteral (hand) vaccination of raccoons was important across all three contingency action areas, but more influential in the Ohio contingency action areas where more raccoons were hand vaccinated. In the Virginia contingency action area, ORV strategies were as important in reducing RRV occupancy as a hand vaccination strategy. The management action to trap, euthanize, and test (TET) raccoons was an important method to increase ERS, yet the impacts of TET on RRV occupancy are not clear. The probability of detecting additional cases of RRV was exceptionally high (>0.95) during the season the index case occurred. The probability of detecting RRV through ERS declined in the seasons following initial TET efforts but remained higher after the contingency action compared to the ERS detection probabilities prior to index case incidence. Local RRV cases were contained within one year and eliminated within 2-3 years of each contingency action.

Assessing the Efficiency of Local Rabies Vaccination Strategies for Raccoons (Procyon lotor) in an Urban Setting

Raccoon rabies virus (RRV) has been managed using multiple vaccination strategies, including oral rabies vaccination and trap-vaccinate-release (TVR). Identifying a rabies vaccination strategy for an area is a nontrivial task. Vaccination strategies differ in the amount of effort and monetary costs required to achieve a particular level of vaccine seroprevalence (efficiency). Simulating host movement relative to different vaccination strategies in silico can provide a useful tool for exploring the efficiency of different vaccination strategies. We refined a previously developed individual-based model of raccoon movement to evaluate vaccination strategies for urban Hamilton, Ontario, Canada. We combined different oral rabies vaccination baiting (hand baiting, helicopter, and bait stations) with TVR strategies and used GPS data to parameterize and simulate raccoon movement in Hamilton. We developed a total of 560 vaccination strategies, in consultation with the Ontario Ministry of Natural Resources and Forestry, for RRV control in Hamilton. We documented the monetary costs of each vaccination strategy and estimated the population seroprevalence. Intervention costs and seroprevalence estimates were used to calculate the efficiency of each strategy to meet targets set for the purpose of RRV control. Estimated seroprevalence across different strategies varied widely, ranging from less than 5% to more than 70%. Increasing bait densities (distributed using by hand or helicopter) led to negligible increase in seroprevalence. Helicopter baiting was the most efficient and TVR was the least efficient, but helicopter-based strategies led to lower levels of seroprevalence (6-12%) than did TVR-based strategies (17-70%). Our simulations indicated that a mixed strategy including at least some TVR may be the most efficient strategy for a local urban RRV control program when seroprevalence levels >30% may be required. Our simulations provide information regarding the efficiency of different vaccination strategies for raccoon populations, to guide local RRV control in urban settings.

Capturing free-roaming dogs for sterilisation: A multi-site study in Goa, India

Sterilisation and rabies vaccination programs seek to manage free-roaming domestic dog (Canis familiaris) populations with the aim to reduce inter-species disease transmission and conflicts. As effective, permanent, remotely-administered options are not yet available for sterilisation, and oral vaccination is not yet commonly used; free-roaming dogs are typically captured for these interventions. There is a paucity of information describing how dog capture rates change over time within defined areas following repeated capture efforts. This data is needed to allow efficient dog capture programmes to be developed. Using spatial co-ordinates of dog capture, we characterise where dogs are more likely to be captured in six catch-sterilise-release campaigns, in Goa state, India. Combining capture numbers with population survey data collected in five sites, we document the increasing difficulty of catching entire (non-sterilised) dogs as sterilisation coverage increases and demonstrate how this leads to increased unit costs. Accounting for the extra resources required to capture dogs when sterilisation coverage is high will improve estimation of the resources required to manage free-roaming dog populations and assist in planning the most efficient intervention strategies.

Research trends in rabies vaccine in the last three decades: a bibliometric analysis of global perspective

INTRODUCTION

Rabies is an infectious zoonotic viral disease which mainly occurs in Africa and Asia. Dogs are predominantly responsible for rabies transmission contributing up to 99% of all human rabies cases. Rabies is a vaccine preventable disease in both animals and humans.

OBJECTIVE

This study aimed to quantify and characterize the scientific literature and identify the top most cited studies in rabies vaccine research (RVR) from 1991 to 2020.

METHODS

The data used in this study were downloaded from Web of Science Core Collection (WoSCC), Science Citation Index-Expanded (SCI-E) database. Network visualization analysis was performed using VOSviewer software.

RESULTS

A total of 1,042 papers (article: n = 986, 94.6%, review: n = 56, 5.4%) were included in this study. These have been cited 17,390 times with an average citation per paper was 16.69 times. The most frequent publication year was 2019 (n = 75, 7.2%). More than 55% studies were published from the United State of America (USA) (n = 380, 36.5%), France (n = 128, 12.3%), and China (n = 97, 9.3%). The most studied Web of Science (WoS) category was immunology (n = 344, 33%). The most prolific author in RVR was Rupprecht CE (n = 55, 5.3%). 'Vaccine' was the leading journal (n = 218, 20.9%). Rabies was the most widely used keyword.

CONCLUSION

Abundant literature has been published on RVR in developed countries. This study might provide a reference to understand the current and future research trends in RVR. In developing countries research collaboration and co-operation among institutes and researchers needs to be strengthened with developed countries.

Domestic dog demographics and estimates of canine vaccination coverage in a rural area of Zambia for the elimination of rabies

Background

An estimated 75% or more of the human rabies cases in Africa occur in rural settings, which underscores the importance of rabies control in these areas. Understanding dog demographics can help design strategies for rabies control and plan and conduct canine mass vaccination campaigns effectively in African countries.

Methodology/Principal findings

A cross-sectional survey was conducted to investigate domestic dog demographics in Kalambabakali, in the rural Mazabuka District of Zambia. The population of ownerless dogs and the total achievable vaccination coverage among the total dog population was estimated using the capture-recapture-based Bayesian model by conducting a canine mass vaccination campaign. This study revealed that 29% of the domestic dog population was under one year old, and 57.7% of those were under three months old and thus were not eligible for the canine rabies vaccination in Zambia. The population growth was estimated at 15% per annum based on the cross-sectional household survey. The population of ownerless dogs was estimated to be small, with an ownerless-to-owned-dog ratio of 0.01–0.06 in the target zones. The achieved overall vaccination coverage from the first mass vaccination was estimated 19.8–51.6%. This low coverage was principally attributed to the owners’ lack of information, unavailability, and dog-handling difficulties. The follow-up mass vaccination campaign achieved an overall coverage of 54.8–76.2%.

Conclusions/Significance

This paper indicates the potential for controlling canine rabies through mass vaccination in rural Zambia. Rabies education and responsible dog ownership are required to achieve high and sustainable vaccination coverage. Our findings also propose including puppies below three months old in the target population for rabies vaccination and emphasize that securing an annual enforcement of canine mass vaccination that reaches 70% coverage in the dog population is necessary to maintain protective herd immunity.

Because dogs are the main transmitter of rabies to humans, controlling rabies in dogs is essential for preventing rabies in humans. Canine vaccination is well-known as the most effective measure for controlling rabies in dogs. Understanding the demographics and dynamics of dog populations is important when designing efficient canine vaccination strategies. Furthermore, protective herd immunity in the total dog population should be attained through the vaccination of owned dogs since ownerless dogs are not usually covered in such campaigns. This study investigated domestic dog demographics and estimated the number of ownerless dogs to finally estimate the vaccination coverage among the overall dog population achievable through a mass vaccination campaign in a rural setting in Mazabuka District, Zambia. The target domestic dog population was young, and population growth was estimated at 15% annually based on the cross-sectional survey. The vaccination coverage attained by providing free canine mass vaccination campaigns was eventually estimated as 54.8–76.2% in the overall dog population, coupled with the estimate that the ownerless dog population was quite small. Our findings emphasize the necessity of conducting annual canine mass vaccinations, including puppies, that target 70% coverage in the dog population to maintain protective herd immunity.

Current issues and gaps in the implementation of rabies prevention in Ukraine in recent decades

Ukraine remains the only country in Europe where rabies is widespread among animals and humans. Annually there are about 1,600 rabies cases in animals in Ukraine and sporadic cases in humans have been registered despite the conducting of preventive measures. Therefore, the aim of the study was to inspect the failures in rabies prevention, indicate the top reasons for human cases and highlights the risk of animal attacks in view of their species and geographical distribution in Ukraine during 1996–2020. The following archival state materials were used for analysis: from the Ministry of Health of Ukraine and from the annual reports of oblast departments of the State Service of Ukraine for Food Safety and Consumer Protection. In general, more than 84,000 people (187.4 per 100,000 of the population) were affected by bites or harmful contact with animals every year, among them, 2,155 people were victims of rabid animals. Post-exposure prophylaxis (PEP) was prescribed annually, on average, for 21,434 patients (25.5% of all victims). Most people were attacked by cats and dogs that had owners (71.5%). The frequency of the proportion of the risk of attacks by rabid dogs on humans was (1:124), from cats (1:25), wild animals (1:7), and farm animals (1:2), but the largest general proportion of animal attacks on people was from dogs – 838,635 attacks (77.7%). Thus, due to the permanently higher level of contact with people, attacks by dogs remains more dangerous. Geographically attacks on humans by domestic carnivores were observed most commonly in the east part of Ukraine due to the high urbanization of the region and the high density of the human population. A large number of attacks by foxes was observed in the west part of Ukraine due to the larger area of forests and fields. During the last 25 years, there have been 63 human rabies cases. The main sources of rabies were dogs (24 cases) and cats (22 cases). The main causes of development of rabies were: failure to receive the PEP due to the absence of a visit to a hospital after an attack of an animal (n = 38), failures in prescribing PEP (n = 15), failure of PEP (n = 10). In conclusion, the gaps in the control measures against rabies are the lack of agreed coordination of inter-sectoral links, the lack of significant efforts to raise public awareness and the lack of funding for prophylaxis programmes for humans and animals. Our future research will be aimed at modelling the transmission of rabies from the pet population to humans.

Modelling the factors affecting the probability for local rabies elimination by strategic control

Dog rabies has been recognized from ancient times and remains widespread across the developing world with an estimated 59,000 people dying annually from the disease. In 2011 a tri-partite alliance consisting of the OIE, the WHO and the FAO committed to globally eliminating dog-mediated human rabies by 2030. Regardless of global support, the responsibility remains with local program managers to implement successful elimination programs. It is well known that vaccination programs have a high probability of successful elimination if they achieve a population-coverage of 70%. It is often quoted that reducing population turnover (typically through sterilizations) raises the probability for local elimination by maintaining herd immunity for longer. Besides this, other factors that affect rabies elimination are rarely mentioned. This paper investigates the probability for local elimination as it relates to immunity, fecundity, dog population size, infectivity (bite rates), in-migration of immune-naïve dogs, and the initial incidence. To achieve this, an individual-based, stochastic, transmission model was manipulated to create a dataset covering combinations of factors that may affect elimination. The results thereof were analysed using a logistic regression model with elimination as the dependent variable. Our results suggest that smaller dog populations, lower infectivity and lower incidence (such as when epidemics start with single introductions) strongly increased the probability for elimination at wide ranges of vaccination levels. Lower fecundity and lower in-migration had weak effects. We discuss the importance of these findings in terms of their impact and their practical application in the design of dog-mediated rabies control programs.

Most guidelines for rabies control call for at least 70% vaccination coverage of dogs. This level of immunity has a very high probability for the local elimination of rabies, but it is often not an achievable ideal due to resource constraints. Campaign managers can be strategic on how they allocate their resources. Lower infectivity rates are present in areas with more restricted dog movements and have higher probabilities for elimination at lower vaccination rates. Smaller sub-populations have higher probabilities for elimination at the same vaccination coverage levels compared to larger sub-populations. Vaccinating immune corridors can divide meta-populations into smaller sub-populations that are likely to result in elimination either due to their small size or due to the local low infectivity. Areas already free of rabies require lower vaccination levels to maintain freedom compared to endemic areas. Where donors do not specifically require sterilization campaigns, funds meant for rabies control should not be diverted to sterilizations.

Role of Oral Rabies Vaccines in the Elimination of Dog-Mediated Human Rabies Deaths

Domestic dogs are responsible for nearly all the »59,000 global human rabies deaths that occur annually. Numerous control measures have been successful at eliminating dog-mediated human rabies deaths in upper-income countries, including dog population management, parenteral dog vaccination programs, access to human rabies vaccines, and education programs for bite prevention and wound treatment. Implementing these techniques in resource-poor settings can be challenging; perhaps the greatest challenge is maintaining adequate herd immunity in free-roaming dog populations. Oral rabies vaccines have been a cornerstone in rabies virus elimination from wildlife populations; however, oral vaccines have never been effectively used to control dog-mediated rabies. Here, we convey the perspectives of the World Organisation for Animal Health Rabies Reference Laboratory Directors, the World Organisation for Animal Health expert committee on dog rabies control, and World Health Organization regarding the role of oral vaccines for dogs. We also issue recommendations for overcoming hesitations to expedited field use of appropriate oral vaccines.

An economic case study of the control of dog-mediated rabies by an animal welfare organisation in Jaipur, India

A global strategic plan for the elimination of dog-mediated human rabies deaths by 2030 was announced in 2018. The cost-effectiveness of annual mass dog vaccination programmes, as a control and elimination method, has been advocated on many occasions. Complementary methods, such as animal birth control (ABC) activities, have received less attention. This paper provides a case-study of a programme operated by Help in Suffering (HIS) in Jaipur, India from 1994/95 until 2016/17 comprising both ABC and additional vaccination-only activities. The availability of cost data alongside information on dog numbers, dog bites and human rabies cases provided an exceptionally detailed and unique retrospective dataset recording actual events and expenditures. Updated to 2016/17 prices, the total cost of the programme was 658,744 USD. Since 2007/2008, activity costs have been separated and returned costs of 10.78 USD per dog, both sterilised and vaccinated, and 1.86 USD per dog, vaccinated only. Over the course of the programme, the number of disability-adjusted life years (DALYs) due to premature death and the distress associated with dog bites was estimated to be 36,246 fewer than would have been expected if HIS had not been operating, based on a counterfactual scenario using pre-intervention values. Linking the DALY figure to the cost of the activities undertaken by HIS yields a cost of 26 USD per DALY averted. Discounted at 3%, the DALYs averted equate to 16,587 at a cost of 40 USD per DALY averted. Both cases make it a very cost-effective intervention, in relation to the threshold of investing one year's gross domestic product (GDP) per DALY averted (1981 USD in 2016/17). The monetary benefit from fewer dog bites and clinical human rabies cases requiring treatment amounted to 5.62 million USD after discounting, which, if attributed to Help in Suffering, yields a monetary benefit-cost ratio of 8.5. Thus, the potential monetary benefits greatly outweigh the programme costs, even without considering the DALYs averted. If a modest notional monetary value of one year's GDP is assigned to represent the human capital or production value of DALYs averted, the discounted societal economic benefit reaches 38.48 million USD and implies a benefit-cost ratio of 58.4. These economic analyses demonstrate that ABC activities in combination with additional vaccination efforts can be a cost-effective control measure for dog-mediated human rabies.

Rabies Vaccination of 6-Week-Old Puppies Born to Immunized Mothers: A Randomized Controlled Trial in a High-Mortality Population of Owned, Free-Roaming Dogs

To achieve global elimination of human rabies from dogs by 2030, evidence-based strategies for effective dog vaccination are needed. Current guidelines recommend inclusion of dogs younger than 3 months in mass rabies vaccination campaigns, although available vaccines are only recommended for use by manufacturers in older dogs, ostensibly due to concerns over interference of maternally-acquired immunity with immune response to the vaccine. Adverse effects of vaccination in this age group of dogs have also not been adequately assessed under field conditions. In a single-site, owner-blinded, randomized, placebo-controlled trial in puppies born to mothers vaccinated within the previous 18 months in a high-mortality population of owned, free-roaming dogs in South Africa, we assessed immunogenicity and effect on survival to all causes of mortality of a single dose of rabies vaccine administered at 6 weeks of age. We found that puppies did not have appreciable levels of maternally-derived antibodies at 6 weeks of age (geometric mean titer 0.065 IU/mL, 95% CI 0.061–0.069; n = 346), and that 88% (95% CI 80.7–93.3) of puppies vaccinated at 6 weeks had titers ≥0.5 IU/mL 21 days later (n = 117). Although the average effect of vaccination on survival was not statistically significant (hazard ratio [HR] 1.35, 95% CI 0.83–2.18), this effect was modified by sex (p = 0.02), with the HR in females 3.09 (95% CI 1.24–7.69) and the HR in males 0.79 (95% CI 0.41–1.53). We speculate that this effect is related to the observed survival advantage that females had over males in the unvaccinated group (HR 0.27; 95% CI 0.11–0.70), with vaccination eroding this advantage through as-yet-unknown mechanisms.