A metapopulation model of dog rabies transmission in N'Djamena, Chad

Benefit-cost analysis of coordinated strategies for control of rabies in Africa

Previous research suggests that dog mass vaccination campaigns can eliminate rabies locally, resulting in large human and animal life gains. Despite these demonstrated benefits, dog vaccination programs remain scarce on the African continent. We conducted a benefit-cost analysis to demonstrate that engaging into vaccination campaigns is the dominant strategy for most countries even in the absence of coordinated action between them. And quantify how coordinated policy measures across countries in Africa could impact rabies incidence and associated costs. We show that coordinated dog mass vaccination between countries and PEP would lead to the elimination of dog rabies in Africa with total welfare gains of USD 9.5 billion (95% CI: 8.1 - 11.4 billion) between 2024 and 2054 (30 years). Coordinated disease control between African countries can lead to more socially and ecologically equitable outcomes by reducing the number of lost human lives to almost zero and possibly eliminating rabies.

Electronic application for rabies management improves surveillance, data quality, and investigator experience in Haiti

Background

Integrated bite case management (IBCM) is a multi-sectoral response to animal-bites which reduces human and canine rabies mortality through animal quarantine, bite-victim counseling, and vaccination tracking. Haiti's national rabies surveillance program was established in 2013 using paper-based IBCM (pIBCM) with adoption of an electronic smartphone application (eIBCM) in 2018.

Methods

We evaluated the feasibility of implementing the electronic app in Haiti and compared pIBCM and eIBCM data quality collected January 2013–August 2019. Deaths prevented, cost-per-death averted, and cost-per-investigation during use of pIBCM and eIBCM were estimated using a previously validated rabies cost-effectiveness tool that accounted for bite-victim demographics; probability of acquiring rabies; post-exposure prophylaxis; and costs including training, supplies, and salaries. We compared pIBCM and eIBCM based on data comprehensiveness, completeness, and reporting efficiency. Surveys were administered to IBCM staff to evaluate the usefulness, simplicity, flexibility, and acceptability of eIBCM.

Results

Of 15,526 investigations, 79% were paper-based and 21% electronic. IBCM prevented 241 (estimated) human rabies deaths. Using pIBCM, cost-per-death averted was $2,692 and the cost-per-investigation was $21.02; up to 55 data variables were collected per investigation; data transmission took 26 days to reach national staff, and 180 days until analysis. Using eIBCM, the cost-per-death averted was $1,247 and the cost-per-investigation was $22.70; up to 174 data variables were collected per investigation; data transmission took 3 days to reach national staff, and 30 days until analysis. Among 12,194 pIBCM investigations, 55% were mappable by commune, compared to 100% of eIBCM investigations mappable by GPS. Animal case definitions were incorrectly ascribed by investigators in 5.5% of pIBCM investigations and zero for eIBCM; typically, errors were in determining probable vs. suspect case assignments. Overall, eIBCM was well-accepted by staff, who reported the app is easy-to-use, facilitates investigations, and compared to pIBCM hastens data reporting.

Discussion

In Haiti, eIBCM showed improved data completeness, data quality, and shorter notification times with minimal increase in operational cost. The electronic app is simple-to-use and facilitates IBCM investigations. Rabies endemic countries could refer to eIBCM in Haiti as a cost-effective means to reduce human rabies mortality and improve surveillance capacity.

Advancing One human-animal-environment Health for global health security: what does the evidence say?

In this Series paper, we review the contributions of One Health approaches (ie, at the human-animal-environment interface) to improve global health security across a range of health hazards and we summarise contemporary evidence of incremental benefits of a One Health approach. We assessed how One Health approaches were reported to the Food and Agricultural Organization of the UN, the World Organisation for Animal Health (WOAH, formerly OIE), and WHO, within the monitoring and assessment frameworks, including WHO International Health Regulations (2005) and WOAH Performance of Veterinary Services. We reviewed One Health theoretical foundations, methods, and case studies. Examples from joint health services and infrastructure, surveillance-response systems, surveillance of antimicrobial resistance, food safety and security, environmental hazards, water and sanitation, and zoonoses control clearly show incremental benefits of One Health approaches. One Health approaches appear to be most effective and sustainable in the prevention, preparedness, and early detection and investigation of evolving risks and hazards; the evidence base for their application is strongest in the control of endemic and neglected tropical diseases. For benefits to be maximised and extended, improved One Health operationalisation is needed by strengthening multisectoral coordination mechanisms at national, regional, and global levels.

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.

The effects of geographical distributions of buildings and roads on the spatiotemporal spread of canine rabies: An individual-based modeling study

Rabies is a fatal disease that has been a serious health concern, especially in developing countries. Although rabies is preventable by vaccination, the spread still occurs sporadically in many countries, including Thailand. Geographical structures, habitats, and behaviors of host populations are essential factors that may result in an enormous impact on the mechanism of propagation and persistence of the disease. To investigate the role of geographical structures on the transmission dynamics of canine rabies, we developed a stochastic individual-based model that integrates the exact configuration of buildings and roads. In our model, the spatial distribution of dogs was estimated based on the distribution of buildings, with roads considered to facilitate dog movement. Two contrasting areas with high- and low-risk of rabies transmission in Thailand, namely, Hatyai and Tepha districts, were chosen as study sites. Our modeling results indicated that the distinct geographical structures of buildings and roads in Hatyai and Tepha could contribute to the difference in the rabies transmission dynamics in these two areas. The high density of buildings and roads in Hatyai could facilitate more rabies transmission. We also investigated the impacts of rabies intervention, including reducing the dog population, restricting owned dog movement, and dog vaccination on the spread of canine rabies in these two areas. We found that reducing the dog population alone might not be sufficient for preventing rabies transmission in the high-risk area. Owned dog confinement could reduce more the likelihood of rabies transmission. Finally, a higher vaccination coverage may be required for controlling rabies transmission in the high-risk area compared to the low-risk area.

Preparing liberia for rabies control: Human-dog relationship and practices, and vaccination scenarios

To reach zero dog-related human rabies deaths by 2030, Liberia must prioritize rabies as a public health threat. Understanding dog demography parameters are imperative and sets the basis for planning cost-effective and sustainable mass dog vaccination programs nationwide. We conducted a cross-sectional household survey in eleven rural districts of Bong and one urban district of Montserrado County to gather baseline information on the canine population, human-mediated dog movements, people's relationships and practices towards dogs, and further information to estimate costs for a nationwide campaign. In total, 1282 respondents were interviewed (612 rural and 670 urban). About 34% of the rural and 37% of the urban households owned at least one dog. The canine: human ratios were 1:6.1 in the rural and1:5.6 in the urban area and did not differ notably among both counties. The estimated canine population for Liberia is 594,640. The majority of respondents (55%) reported poor waste disposal. Muslims were less likely to own a dog than Christians (39% vs 19% OR: 0.4 95% CI: 0.2-0.6) (p< 0.001). Six percent of respondents mentioned that a family member was exposed to a dog bite in the past year, and most victims were adult males. Four of the victims reportedly died after showing rabies compatible symptoms. Twenty-seven percent of dog-owning households in rural areas reported that at least one dog originated from urban areas, and 2% of urban households brought in dogs from another country. In addition, 43% of respondents consumed dog meat at least once. Fifty percent of the respondents claimed knowledge of rabies but only 5.7% and 1.9% mentioned rabies transmission through rabies-infected saliva and rabies-infected mucus on broken skin. Forty percent of the respondents did not know whether rabies was incurable in humans once clinical signs appear. Assuming 30 vaccinators could vaccinate 50 dogs per day for eighteen months (371 working days), the total cost for the vaccination of the national Liberian canine population is estimated at 1.6 million (USD) for one vaccination round. Our study reveals an overall poor disease knowledge and the potential for spread of rabies in the study areas. A nationwide rabies awareness is crucial to enhance rabies prevention and control through mass dog vaccination.

Modelling the influence of naturally acquired immunity from subclinical infection on outbreak dynamics and persistence of rabies in domestic dogs

A number of mathematical models have been developed for canine rabies to explore dynamics and inform control strategies. A common assumption of these models is that naturally acquired immunity plays no role in rabies dynamics. However, empirical studies have detected rabies-specific antibodies in healthy, unvaccinated domestic dogs, potentially due to immunizing, non-lethal exposure. We developed a stochastic model for canine rabies, parameterised for Laikipia County, Kenya, to explore the implications of different scenarios for naturally acquired immunity to rabies in domestic dogs. Simulating these scenarios using a non-spatial model indicated that low levels of immunity can act to limit rabies incidence and prevent depletion of the domestic dog population, increasing the probability of disease persistence. However, incorporating spatial structure and human response to high rabies incidence allowed the virus to persist in the absence of immunity. While low levels of immunity therefore had limited influence under a more realistic approximation of rabies dynamics, high rates of exposure leading to immunizing non-lethal exposure were required to produce population-level seroprevalences comparable with those reported in empirical studies. False positives and/or spatial variation may contribute to high empirical seroprevalences. However, if high seroprevalences are related to high exposure rates, these findings support the need for high vaccination coverage to effectively control this disease.

Mathematical modelling and phylodynamics for the study of dog rabies dynamics and control: A scoping review

BACKGROUND

Rabies is a fatal yet vaccine-preventable disease. In the last two decades, domestic dog populations have been shown to constitute the predominant reservoir of rabies in developing countries, causing 99% of human rabies cases. Despite substantial control efforts, dog rabies is still widely endemic and is spreading across previously rabies-free areas. Developing a detailed understanding of dog rabies dynamics and the impact of vaccination is essential to optimize existing control strategies and developing new ones. In this scoping review, we aimed at disentangling the respective contributions of mathematical models and phylodynamic approaches to advancing the understanding of rabies dynamics and control in domestic dog populations. We also addressed the methodological limitations of both approaches and the remaining issues related to studying rabies spread and how this could be applied to rabies control.

METHODOLOGY/PRINCIPAL FINDINGS

We reviewed how mathematical modelling of disease dynamics and phylodynamics have been developed and used to characterize dog rabies dynamics and control. Through a detailed search of the PubMed, Web of Science, and Scopus databases, we identified a total of n = 59 relevant studies using mathematical models (n = 30), phylodynamic inference (n = 22) and interdisciplinary approaches (n = 7). We found that despite often relying on scarce rabies epidemiological data, mathematical models investigated multiple aspects of rabies dynamics and control. These models confirmed the overwhelming efficacy of massive dog vaccination campaigns in all settings and unraveled the role of dog population structure and frequent introductions in dog rabies maintenance. Phylodynamic approaches successfully disentangled the evolutionary and environmental determinants of rabies dispersal and consistently reported support for the role of reintroduction events and human-mediated transportation over long distances in the maintenance of rabies in endemic areas. Potential biases in data collection still need to be properly accounted for in most of these analyses. Finally, interdisciplinary studies were determined to provide the most comprehensive assessments through hypothesis generation and testing. They also represent new avenues, especially concerning the reconstruction of local transmission chains or clusters through data integration.

CONCLUSIONS/SIGNIFICANCE

Despite advances in rabies knowledge, substantial uncertainty remains regarding the mechanisms of local spread, the role of wildlife in dog rabies maintenance, and the impact of community behavior on the efficacy of control strategies including vaccination of dogs. Future integrative approaches that use phylodynamic analyses and mechanistic models within a single framework could take full advantage of not only viral sequences but also additional epidemiological information as well as dog ecology data to refine our understanding of rabies spread and control. This would represent a significant improvement on past studies and a promising opportunity for canine rabies research in the frame of the One Health concept that aims to achieve better public health outcomes through cross-sector collaboration.

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

In Latin America, there has been tremendous progress towards eliminating canine rabies. Major components of rabies elimination programs leading to these successes have been constant and regular surveillance for rabid dogs and uninterrupted yearly mass dog vaccination campaigns. Unfortunately, vital measures to control COVID-19 have had the negative trade-off of jeopardizing these rabies elimination and prevention activities. 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 to create a conceptual framework for how different disruptions may affect rabies virus transmission. We parameterized the model for conditions found in Arequipa, Peru, a city with active rabies virus transmission. We examined our results over a range of plausible values for R0 (1.36-2.0). Also, we prospectively evaluated surveillance data during the pandemic to detect temporal changes. Our model suggests that a decrease in canine vaccination coverage as well as decreased surveillance could lead to a sharp rise in canine rabies within months. These results were consistent over all plausible values of R0. Surveillance data from late 2020 and early 2021 confirms that in Arequipa, Peru, rabies cases are on an increasing trajectory. The rising rabies trends in Arequipa, if indicative to the region as whole, suggest that the achievements made in Latin America towards the elimination of dog-mediated human rabies may be in jeopardy.

The Spread of Rabies Among Dogs in Pranburi District, Thailand: A Metapopulation Modeling Approach

Rabies, a deadly zoonotic disease, is causing serious public health problems worldwide. Dogs are considered the main reservoir for rabies infection in humans. A better understanding of the dissemination of rabies in the dog population is crucial. The present study, therefore, aimed to explore the subpopulation of dogs roaming around rabies-outbreak areas and the model of its possible spread. We used a Cross-K function to investigate the spatial clustering between the locations of dog rabies cases and the feeding points of a stray dog feeder. We then observed the social interaction of dogs in a community using a metapopulation analysis and further simulated the possible spread of rabies within this population. We found that the reported rabies cases were spatially clustered with the routes of the dog feeder. Therefore, more sustainable stray dog management is required. Based on our community dog observations, we found 20 groups comprising 222 dogs with an average of 11 dogs per group. In our infectious model, we suggested that 47.7% of dogs are likely to be infected in a year if no interventions are implemented. Therefore, the veterinary authorities should rigorously strengthen their rabies prevention and control strategies to protect both animal and human health.

Evaluating the role of surgical sterilisation in canine rabies control: A systematic review of impact and outcomes

Current recommendations for the elimination of canine-mediated human rabies focus on mass dog vaccination as the most feasible and cost-effective strategy. However, attempts to control rabies are often combined with canine surgical sterilisation programmes. The added value of sterilisation is widely debated. A systematic review was undertaken to compare the outcomes and impact of vaccination and sterilisation programmes with vaccination only programmes. A systematic search of three electronic databases (CAB Abstracts, Medline and Global Health) and grey literature was performed. From 8696 abstracts found, 5554 unique studies were identified, and 16 studies met the inclusion criteria. Eight described vaccination only programmes and eight described vaccination and sterilisation programmes. Indicators of impact measured were dog bites and/or doses of post-exposure prophylaxis administered; numbers of dog and/or human rabies cases; dog population demographic changes; changes in health and welfare of dogs, and indicators related to human behaviour change. The studies were contextually very diverse, programmes being implemented were complex, and there was variation in measurement and reporting of key indicators. Therefore, it was difficult to compare the two types of intervention, and impossible to make an evaluation of the role of sterilisation, using this evidence. Given the large number of vaccination and sterilisation programmes conducted globally, the lack of studies available for review highlights a gap in data collection or reporting, essential for impact assessment. There are several knowledge gaps concerning the impact of the sterilisation component alone, as well as subsequent effects on rabies transmission and control. Prospective studies comparing the outcomes and impact of the two interventions would be required in order to establish any additional contribution of sterilisation, as well as the underlying mechanisms driving any changes. In the absence of such evidence, the priority for rabies control objectives should be implementation of mass vaccination, as currently recommended by the World Health Organisation.

Long-range movements coupled with heterogeneous incubation period sustain dog rabies at the national scale in Africa

Dog-transmitted rabies is responsible for more than 98% of human cases worldwide, remaining a persistent problem in developing countries. Mass vaccination targets predominantly major cities, often compromising disease control due to re-introductions. Previous work suggested that areas neighboring cities may behave as the source of these re-introductions. To evaluate this hypothesis, we introduce a spatially explicit metapopulation model for rabies diffusion in Central African Republic. Calibrated on epidemiological data for the capital city, Bangui, the model predicts that long-range movements are essential for continuous re-introductions of rabies-exposed dogs across settlements, eased by the large fluctuations of the incubation period. Bangui's neighborhood, instead, would not be enough to self-sustain the epidemic, contrary to previous expectations. Our findings suggest that restricting long-range travels may be very efficient in limiting rabies persistence in a large and fragmented dog population. Our framework can be applied to other geographical contexts where dog rabies is endemic.

Intervention threshold for epidemic control in susceptible-infected-recovered metapopulation models

Metapopulation epidemic models describe epidemic dynamics in networks of spatially distant patches connected via pathways for migration of individuals. In the present study, we deal with a susceptible-infected-recovered (SIR) metapopulation model where the epidemic process in each patch is represented by an SIR model and the mobility of individuals is assumed to be a homogeneous diffusion. We consider two types of patches including high-risk and low-risk ones under the assumption that a local patch is changed from a high-risk one to a low-risk one by an intervention. We theoretically analyze the intervention threshold which indicates the critical fraction of low-risk patches for preventing a global epidemic outbreak. We show that an intervention targeted to high-degree patches is more effective for epidemic control than a random intervention. The theoretical results are validated by Monte Carlo simulations for synthetic and realistic scale-free patch networks. The theoretical results also reveal that the intervention threshold depends on the human mobility network and the mobility rate. Our approach is useful for exploring better local interventions aimed at containment of epidemics.