Determining the post-elimination level of vaccination needed to prevent re-establishment of dog rabies

Current evidence of the economic value of One Health initiatives: A systematic literature review

Funding and financing for One Health initiatives at country level remain challenging as investments commonly require demonstrated evidence of economic value or returns. The objectives of this review were to i) identify, critically analyse and summarise quantitative evidence of the net economic value of One Health initiatives; ii) document methodologies commonly used in the scientific literature; and iii) describe common challenges and any evidence gaps. Scientific databases were searched for published literature following the PRISMA guidelines and an online survey and workshop with subject matter experts were used to identify relevant grey literature. Studies were included if they reported on quantitative costs and benefits (monetary and non-monetary) and were measured across at least two sectors. Relevant publications were analysed and plotted against the six action tracks of the Quadripartite One Health Joint Plan of Action to help classify the initiatives. Ninety-seven studies were included. Eighty studies involved only two sectors and 78 reported a positive economic value or return. Of those studies that reported a positive return, 49 did not compare with a sectoral counterfactual, 28 studies demonstrated an added value of using a cross-sectoral approach, and 6 studies demonstrated an added value of One Health communication, collaboration, coordination, and capacity building. Included studies most frequently related to endemic zoonotic, neglected tropical and vector-borne diseases, followed by health of the environment and food safety. However, diversity in economic analysis methodology between studies included resulted in difficulty to compare or combine findings. While there is a growing body of evidence of the value of One Health initiatives, a substantial part of the evidence still focuses on "traditional" One Health topics, particularly zoonoses. Developing a standardised and practical approach for One Health economic evaluation will facilitate assessment of the added value and gather evidence for One Health to be invested in and endorsed by multiple sectors.

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.

Dogs on the move: Estimating the risk of rabies in imported dogs in the United States, 2015-2022

BACKGROUND

Dog-mediated rabies virus variant (DMRVV), a zoonotic pathogen that causes a deadly disease in animals and humans, is present in more than 100 countries worldwide but has been eliminated from the United States since 2007. In the United States, the U.S. Centers for Disease Control and Prevention has recorded four instances of rabies in dogs imported from DMRVV-enzootic countries since 2015. However, it remains uncertain whether the incidence of DMRVV among imported dogs from these countries significantly surpasses that of domestically acquired variants among domestic U.S. dogs.

AIM

This evaluation aimed to estimate the number of dogs imported from DMRVV-enzootic countries and compare the risk of rabies between imported dogs and the U.S. domestic dog population.

MATERIALS AND METHODS

Data from the CDC's dog import permit system (implemented during 2021 under a temporary suspension of dog importation from DMRVV-enzootic countries) and U.S. Customs and Border Protection's Automated Commercial Environment system, each of which records a segment of dogs entering the U.S. from DMRVV-enzootic countries, was analysed. Additionally, we estimated the incidence rate of rabies in dogs imported from DMRVV-enzootic countries and compared it to the incidence rate within the general U.S. dog population, due to domestically acquired rabies variants, over the eight-year period (2015-2022).

RESULTS

An estimated 72,589 (range, 62,660-86,258) dogs were imported into the United States annually between 2015 and 2022 from DMRVV-enzootic countries. The estimated incidence rate of rabies was 16 times higher (range, 13.2-19.4) in dogs imported from DMRVV-enzootic countries than that estimated for domestically acquired rabies in the general U.S. dog population.

CONCLUSIONS

Preventing human exposure to dogs with DMRVV is a public health priority. The higher risk of rabies in dogs imported from DMRVV-enzootic countries supports the need for importation requirements aimed at preventing the reintroduction of DMRVV into the United States.

Evaluation of the immune response of dogs after a mass vaccination campaign against rabies in Tunisia

BACKGROUND

Rabies (RABV) is an enzootic disease in Tunisia, with dogs being the primary reservoir. Vaccinating dogs is the key to eradicate rabies. Regional Veterinary Services conduct nationwide immunisation campaigns on an annual basis. Evaluation of the immune response is still important to make sure that the vaccination is effective in the conditions of the Tunisian field. In this paper, the FAVN technique was used to test rabies antibody dynamics in dogs from three distinct Tunisian areas observed for one year following a mass vaccination campaign.

RESULTS

On day 30 after vaccination, 75% of all dogs vaccinated during the campaign were sero-positive (titres greater than or equal to 0.5 transformed IU/ml). On day 180, 48% of all dogs were sero-positive. Only 25.6% of primary-vaccinated dogs remained sero-positive on day 180 and 7% on day 365, whereas 91% of previously sero-positive dogs remained sero-positive on day 365.

CONCLUSIONS

Although a single rabies vaccine is successful at stimulating an immunological response, it is recommended that primary-vaccinated dogs have a second booster between one and three months after the initial vaccination to maintain seropositivity. To achieve the rabies eradication objective, all dogs should receive an annual booster to maintain effective immunological protection.

Elimination of human rabies in Goa, India through an integrated One Health approach

Dog-mediated rabies kills tens of thousands of people each year in India, representing one third of the estimated global rabies burden. Whilst the World Health Organization (WHO), World Organization for Animal Health (OIE) and the Food and Agriculture Organization of the United Nations (FAO) have set a target for global dog-mediated human rabies elimination by 2030, examples of large-scale dog vaccination programs demonstrating elimination remain limited in Africa and Asia. We describe the development of a data-driven rabies elimination program from 2013 to 2019 in Goa State, India, culminating in human rabies elimination and a 92% reduction in monthly canine rabies cases. Smartphone technology enabled systematic spatial direction of remote teams to vaccinate over 95,000 dogs at 70% vaccination coverage, and rabies education teams to reach 150,000 children annually. An estimated 2249 disability-adjusted life years (DALYs) were averted over the program period at 526 USD per DALY, making the intervention 'very cost-effective' by WHO definitions. This One Health program demonstrates that human rabies elimination is achievable at the state level in India.

Public health implication towards rabies elimination in Sri Lanka: A systematic review

BACKGROUND/OBJECTIVES

Sri Lanka has been targeted zero rabies by the end of 2025. Towards the elimination, the country needs more effective, evidence-based strategies and efforts to achieve its ultimate goal. Therefore, we conducted a systematic review of scientific literatures and data to assess current human and animal rabies control and prevention strategies in Sri Lanka.

METHODS

We compiled documents regarding current and previous rabies control and prevention activities implemented in the entire country of Sri Lanka. The documents included published literatures issued between 1946 and 2020 from both online databases and university library in Sri Lanka. All the collected documents were screened based on the PRISMA statement and categorized into several types of rabies control and prevention strategies. Official reports including epidemiological data in Sri Lanka were also filed in order to analyze the current trend of rabies control and prevention in the nation.

RESULTS

As of end December 2020, we found 119 scientific literatures regarding rabies control and prevention in Sri Lanka. Human rabies deaths in Sri Lanka have been reduced for the last half century by successful implementation of mass dog vaccination, animal birth control and awareness raising activities. However, the country is still facing on sporadic rabies cases, limited dog vaccination coverage and insufficient dog population management in the district level. Despite the nationwide standard of dog to human ratio of 1:8, there are huge disparities or unknown of dog ecology in regions. Awareness raising including has been enhancing for both general public and school children. Surveillance system is poorly operated so that simultaneous data analysis for decision-making is impractical.

CONCLUSIONS

In order to achieve nationwide rabies elimination, it is highly recommended to implement more effective rabies control and prevention activities and build adequate scientific evidences.

The urgency of resuming disrupted dog rabies vaccination campaigns: a modeling and cost-effectiveness analysis

Dog vaccination is a cost-effective approach to preventing human rabies deaths. In Haiti, the last nation-wide dog vaccination campaign occurred in 2018. We estimated the number of human lives that could be saved by resuming dog vaccination in 2021 compared to 2022 and compared the cost-effectiveness of these two scenarios. We modified a previously published rabies transmission and economic model to estimate trends in dog and human rabies cases in Haiti from 2005 to 2025, with varying assumptions about when dog vaccinations resume. We compared model outputs to surveillance data on human rabies deaths from 2005 to 2020 and animal rabies cases from 2018 to 2020. Model predictions and surveillance data both suggest a 5- to 8-fold increase in animal rabies cases occurred in Haiti's capital city between Fall 2019 and Fall 2020. Restarting dog vaccination in Haiti in 2021 compared to 2022 could save 285 human lives and prevent 6541 human rabies exposures over a five-year period. It may also decrease program costs due to reduced need for human post-exposure prophylaxis. These results show that interruptions in dog vaccination campaigns before elimination is achieved can lead to significant human rabies epidemics if not promptly resumed.

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.

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.

Cost-effectiveness of the national dog rabies prevention and control program in Mexico, 1990-2015

BACKGROUND

Rabies is a viral zoonosis that imposes a substantial disease and economic burden in many developing countries. Dogs are the primary source of rabies transmission; eliminating dog rabies reduces the risk of exposure in humans significantly. Through mass annual dog rabies vaccination campaigns, the national program of rabies control in Mexico progressively reduced rabies cases in dogs and humans since 1990. In 2019, the World Health Organization validated Mexico for eliminating rabies as a public health problem. Using a governmental perspective, we retrospectively assessed the economic costs, effectiveness, and cost-effectiveness of the national program of rabies control in Mexico, 1990-2015.

METHODOLOGY

Combining various data sources, including administrative records, national statistics, and scientific literature, we retrospectively compared the current scenario of annual dog vaccination campaigns and post-exposure prophylaxis (PEP) with a counterfactual scenario without an annual dog vaccination campaign but including PEP. The counterfactual scenario was estimated using a mathematical model of dog rabies transmission (RabiesEcon). We performed a thorough sensitivity analysis of the main results.

PRINCIPAL FINDINGS

Results suggest that in 1990 through 2015, the national dog rabies vaccination program in Mexico prevented about 13,000 human rabies deaths, at an incremental cost (MXN 2015) of $4,700 million (USD 300 million). We estimated an average cost of $360,000 (USD 23,000) per human rabies death averted, $6,500 (USD 410) per additional year-of-life, and $3,000 (USD 190) per dog rabies death averted. Results were robust to several counterfactual scenarios, including high and low rabies transmission scenarios and various assumptions about potential costs without mass dog rabies vaccination campaigns.

CONCLUSIONS

Annual dog rabies vaccination campaigns have eliminated the transmission of dog-to-dog rabies and dog-mediated human rabies deaths in Mexico. According to World Health Organization standards, our results show that the national program of rabies control in Mexico has been highly cost-effective.

Update on lyssaviruses and rabies: will past progress play as prologue in the near term towards future elimination?

Rabies is an ancient, much-feared, and neglected infectious disease. Caused by pathogens in the family Rhabdoviridae, genus Lyssavirus, and distributed globally, this viral zoonosis results in tens of thousands of human fatalities and millions of exposures annually. All mammals are believed susceptible, but only certain taxa act as reservoirs. Dependence upon direct routing to, replication within, and passage from the central nervous system serves as a basic viral strategy for perpetuation. By a combination of stealth and subversion, lyssaviruses are quintessential neurotropic agents and cause an acute, progressive encephalitis. No treatment exists, so prevention is the key. Although not a disease considered for eradication, something of a modern rebirth has been occurring within the field as of late with regard to detection, prevention, and management as well as applied research. For example, within the past decade, new lyssaviruses have been characterized; sensitive and specific diagnostics have been optimized; pure, potent, safe, and efficacious human biologics have improved human prophylaxis; regional efforts have controlled canine rabies by mass immunization; wildlife rabies has been controlled by oral rabies vaccination over large geographic areas in Europe and North America; and debate has resumed over the controversial topic of therapy. Based upon such progress to date, there are certain expectations for the next 10 years. These include pathogen discovery, to uncover additional lyssaviruses in the Old World; laboratory-based surveillance enhancement by simplified, rapid testing; anti-viral drug appearance, based upon an improved appreciation of viral pathobiology and host response; and improvements to canine rabies elimination regionally throughout Africa, Asia, and the Americas by application of the best technical, organizational, economic, and socio-political practices. Significantly, anticipated Gavi support will enable improved access of human rabies vaccines in lesser developed countries at a national level, with integrated bite management, dose-sparing regimens, and a 1 week vaccination schedule.

Portable Rabies Virus Sequencing in Canine Rabies Endemic Countries Using the Oxford Nanopore MinION

As countries with endemic canine rabies progress towards elimination by 2030, it will become necessary to employ techniques to help plan, monitor, and confirm canine rabies elimination. Sequencing can provide critical information to inform control and vaccination strategies by identifying genetically distinct virus variants that may have different host reservoir species or geographic distributions. However, many rabies testing laboratories lack the resources or expertise for sequencing, especially in remote or rural areas where human rabies deaths are highest. We developed a low-cost, high throughput rabies virus sequencing method using the Oxford Nanopore MinION portable sequencer. A total of 259 sequences were generated from diverse rabies virus isolates in public health laboratories lacking rabies virus sequencing capacity in Guatemala, India, Kenya, and Vietnam. Phylogenetic analysis provided valuable insight into rabies virus diversity and distribution in these countries and identified a new rabies virus lineage in Kenya, the first published canine rabies virus sequence from Guatemala, evidence of rabies spread across an international border in Vietnam, and importation of a rabid dog into a state working to become rabies-free in India. Taken together, our evaluation highlights the MinION's potential for low-cost, high volume sequencing of pathogens in locations with limited resources.

The impact of the COVID-19 pandemic on rabies reemergence in Latin America: the case of Arequipa, Peru

Over the past decades, there has been tremendous progress towards eliminating canine rabies in Latin America. Major components of rabies prevention programs in Latin America leading to these successes have been constant and intense surveillance for rabid dogs and uninterrupted yearly mass dog vaccination campaigns. However, vital measures to control COVID-19 in Latin America have had the negative trade-off of jeopardizing these rabies elimination and prevention activities. In this paper, we aimed to assess the effect of interrupting canine rabies surveillance and mass dog vaccination campaigns on rabies trends. We built a deterministic compartment model of dog rabies dynamics parameterized for conditions found in Arequipa, Peru, where there is an ongoing dog rabies epidemic. Our model suggests that a decrease in canine vaccination coverage as well as decreased surveillance leading to an increased length of survival of infected dogs could lead to a sharp rise in canine rabies and, subsequently, human rabies risk. We examined our results over the best estimate of the basic reproductive number in Arequipa (R0 = 1.44) and a range of plausible values for R0 (1.36 - 2). The rising trend was consistent. It is very possible that COVID-19 will continue to challenge our public health departments in the short- and medium-term. Innovative strategies to conduct dog vaccination and rabies surveillance during these trying times should be considered to safeguard the achievements made in Latin America towards the elimination of dog-mediated human rabies.