RESUMEN
The availability of pathogen sequence data and use of genomic surveillance is rapidly increasing. Genomic tools and classification systems need updating to reflect this. Here, rabies virus is used as an example to showcase the potential value of updated genomic tools to enhance surveillance to better understand epidemiological dynamics and improve disease control. Previous studies have described the evolutionary history of rabies virus, however the resulting taxonomy lacks the definition necessary to identify incursions, lineage turnover and transmission routes at high resolution. Here we propose a lineage classification system based on the dynamic nomenclature used for SARS-CoV-2, defining a lineage by phylogenetic methods for tracking virus spread and comparing sequences across geographic areas. We demonstrate this system through application to the globally distributed Cosmopolitan clade of rabies virus, defining 96 total lineages within the clade, beyond the 22 previously reported. We further show how integration of this tool with a new rabies virus sequence data resource (RABV-GLUE) enables rapid application, for example, highlighting lineage dynamics relevant to control and elimination programmes, such as identifying importations and their sources, as well as areas of persistence and routes of virus movement, including transboundary incursions. This system and the tools developed should be useful for coordinating and targeting control programmes and monitoring progress as countries work towards eliminating dog-mediated rabies, as well as having potential for broader application to the surveillance of other viruses.
Asunto(s)
Filogenia , Virus de la Rabia , Rabia , Animales , Perros , Genómica , Rabia/virología , Virus de la Rabia/genéticaRESUMEN
Whether a pathogen entering a new host species results in a single infection or in onward transmission, and potentially an outbreak, depends upon the progression of infection in the index case. Although index infections are rarely observable in nature, experimental inoculations of pathogens into novel host species provide a rich and largely unexploited data source for meta-analyses to identify the host and pathogen determinants of variability in infection outcomes. We analyzed the progressions of 514 experimental cross-species inoculations of rabies virus, a widespread zoonosis which in nature exhibits both dead-end infections and varying levels of sustained transmission in novel hosts. Inoculations originating from bats rather than carnivores, and from warmer- to cooler-bodied species caused infections with shorter incubation periods that were associated with diminished virus excretion. Inoculations between distantly related hosts tended to result in shorter clinical disease periods, which are also expected to impede onward transmission. All effects were modulated by infection dose. Taken together, these results suggest that as host species become more dissimilar, increased virulence might act as a limiting factor preventing onward transmission. These results can explain observed constraints on rabies virus host shifts, describe a previously unrecognized role of host body temperature, and provide a potential explanation for host shifts being less likely between genetically distant species. More generally, our study highlights meta-analyses of experimental infections as a tractable approach to quantify the complex interactions between virus, reservoir, and novel host that shape the outcome of cross-species transmission.
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Interacciones Microbiota-Huesped/genética , Especificidad del Huésped/fisiología , Rabia/transmisión , Animales , Carnívoros , Quirópteros , Reservorios de Enfermedades/microbiología , Interacciones Microbiota-Huesped/fisiología , Humanos , Filogenia , Rabia/epidemiología , Virus de la Rabia/patogenicidad , VirulenciaRESUMEN
The "Zero by 30" strategic plan aims to eliminate human deaths from dog-mediated rabies by 2030 and domestic dog vaccination is a vital component of this strategic plan. In areas where domestic dog vaccination has been implemented, it is important to assess the impact of this intervention. Additionally, understanding temporal and seasonal trends in the incidence of animal rabies cases may assist in optimizing such interventions. Data on the incidence of probable rabies cases in domestic and wild animals were collected between January 2011 and December 2018 in thirteen districts of south-east Tanzania where jackals comprise over 40% of reported rabies cases. Vaccination coverage was estimated over this period, as five domestic dog vaccination campaigns took place in all thirteen districts between 2011 and 2016. Negative binomial generalized linear models were used to explore the impact of domestic dog vaccination on the annual incidence of animal rabies cases, whilst generalized additive models were used to investigate the presence of temporal and/or seasonal trends. Increases in domestic dog vaccination coverage were significantly associated with a decreased incidence of rabies cases in both domestic dogs and jackals. A 35% increase in vaccination coverage was associated with a reduction in the incidence of probable dog rabies cases of between 78.0 and 85.5% (95% confidence intervals ranged from 61.2 to 92.2%) and a reduction in the incidence of probable jackal rabies cases of between 75.3 and 91.2% (95% confidence intervals ranged from 53.0 to 96.1%). A statistically significant common seasonality was identified in the monthly incidence of probable rabies cases in both domestic dogs and jackals with the highest incidence from February to August and lowest incidence from September to January. These results align with evidence supporting the use of domestic dog vaccination as part of control strategies aimed at reducing animal rabies cases in both domestic dogs and jackals in this region. The presence of a common seasonal trend requires further investigation but may have implications for the timing of future vaccination campaigns.
Asunto(s)
Enfermedades de los Perros , Vacunas Antirrábicas , Rabia , Animales , Perros , Humanos , Animales Domésticos , Enfermedades de los Perros/epidemiología , Enfermedades de los Perros/prevención & control , Rabia/epidemiología , Rabia/prevención & control , Rabia/veterinaria , Animales Salvajes , Incidencia , Vacunación/veterinariaRESUMEN
BACKGROUND: International organizations advocate for the elimination of dog-mediated rabies, but there is only limited guidance on interpreting surveillance data for managing elimination programmes. With the regional programme in Latin America approaching elimination of dog-mediated rabies, we aimed to develop a tool to evaluate the programme's performance and generate locally-tailored rabies control programme management guidance to overcome remaining obstacles. METHODS: We developed and validated a robust algorithm to classify progress towards rabies elimination within sub-national administrative units, which we applied to surveillance data from Brazil and Mexico. The method combines criteria that are easy to understand, including logistic regression analysis of case detection time series, assessment of rabies virus variants, and of incursion risk. Subjecting the algorithm to robustness testing, we further employed simulated data sub-sampled at differing levels of case detection to assess the algorithm's performance and sensitivity to surveillance quality. RESULTS: Our tool demonstrated clear epidemiological transitions in Mexico and Brazil: most states progressed rapidly towards elimination, but a few regressed due to incursions and control lapses. In 2015, dog-mediated rabies continued to circulate in the poorest states, with foci remaining in only 1 of 32 states in Mexico, and 2 of 27 in Brazil, posing incursion risks to the wider region. The classification tool was robust in determining epidemiological status irrespective of most levels of surveillance quality. In endemic settings, surveillance would need to detect less than 2.5% of all circulating cases to result in misclassification, whereas in settings where incursions become the main source of cases the threshold detection level for correct classification should not be less than 5%. CONCLUSION: Our tool provides guidance on how to progress effectively towards elimination targets and tailor strategies to local epidemiological situations, while revealing insights into rabies dynamics. Post-campaign assessments of dog vaccination coverage in endemic states, and enhanced surveillance to verify and maintain freedom in states threatened by incursions were identified as priorities to catalyze progress towards elimination. Our finding suggests genomic surveillance should become increasingly valuable during the endgame for discriminating circulating variants and pinpointing sources of incursions.
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Erradicación de la Enfermedad/métodos , Enfermedades de los Perros/epidemiología , Enfermedades de los Perros/prevención & control , Control de Infecciones/métodos , Virus de la Rabia/genética , Rabia/epidemiología , Rabia/prevención & control , Algoritmos , Animales , Brasil/epidemiología , Perros , Genómica/métodos , Humanos , América Latina/epidemiología , Vacunación Masiva , México/epidemiología , Rabia/transmisión , Rabia/virología , Estudios Retrospectivos , Cobertura de VacunaciónRESUMEN
Understanding multi-host pathogen maintenance and transmission dynamics is critical for disease control. However, transmission dynamics remain enigmatic largely because they are difficult to observe directly, particularly in wildlife. Here, we investigate the transmission dynamics of canine parvovirus (CPV) using state-space modelling of 20 years of CPV serology data from domestic dogs and African lions in the Serengeti ecosystem. We show that, although vaccination reduces the probability of infection in dogs, and despite indirect enhancement of population seropositivity as a result of vaccine shedding, the vaccination coverage achieved has been insufficient to prevent CPV from becoming widespread. CPV is maintained by the dog population and has become endemic with approximately 3.5-year cycles and prevalence reaching approximately 80%. While the estimated prevalence in lions is lower, peaks of infection consistently follow those in dogs. Dogs exposed to CPV are also more likely to become infected with a second multi-host pathogen, canine distemper virus. However, vaccination can weaken this coupling, raising questions about the value of monovalent versus polyvalent vaccines against these two pathogens. Our findings highlight the need to consider both pathogen- and host-level community interactions when seeking to understand the dynamics of multi-host pathogens and their implications for conservation, disease surveillance and control programmes.
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Enfermedades de los Perros/transmisión , Leones , Infecciones por Parvoviridae/veterinaria , Parvovirus Canino/fisiología , Animales , Teorema de Bayes , Enfermedades de los Perros/epidemiología , Perros , Ecosistema , Modelos Biológicos , Infecciones por Parvoviridae/epidemiología , Infecciones por Parvoviridae/transmisión , Prevalencia , Estudios Seroepidemiológicos , Tanzanía/epidemiologíaRESUMEN
Landscape heterogeneity plays an important role in disease spread and persistence, but quantifying landscape influences and their scale dependence is challenging. Studies have focused on how environmental features or global transport networks influence pathogen invasion and spread, but their influence on local transmission dynamics that underpin the persistence of endemic diseases remains unexplored. Bayesian phylogeographic frameworks that incorporate spatial heterogeneities are promising tools for analysing linked epidemiological, environmental and genetic data. Here, we extend these methodological approaches to decipher the relative contribution and scale-dependent effects of landscape influences on the transmission of endemic rabies virus in Serengeti district, Tanzania (area ~4,900 km2 ). Utilizing detailed epidemiological data and 152 complete viral genomes collected between 2004 and 2013, we show that the localized presence of dogs but not their density is the most important determinant of diffusion, implying that culling will be ineffective for rabies control. Rivers and roads acted as barriers and facilitators to viral spread, respectively, and vaccination impeded diffusion despite variable annual coverage. Notably, we found that landscape effects were scale-dependent: rivers were barriers and roads facilitators on larger scales, whereas the distribution of dogs was important for rabies dispersal across multiple scales. This nuanced understanding of the spatial processes that underpin rabies transmission can be exploited for targeted control at the scale where it will have the greatest impact. Moreover, this research demonstrates how current phylogeographic frameworks can be adapted to improve our understanding of endemic disease dynamics at different spatial scales.
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Perros/virología , Virus de la Rabia/fisiología , Zoonosis/transmisión , Zoonosis/virología , Animales , Movimiento , Filogeografía , TanzaníaRESUMEN
Morbilliviruses cause many diseases of medical and veterinary importance, and although some (e.g., measles and rinderpest) have been controlled successfully, others, such as canine distemper virus (CDV), are a growing concern. A propensity for host-switching has resulted in CDV emergence in new species, including endangered wildlife, posing challenges for controlling disease in multispecies communities. CDV is typically associated with domestic dogs, but little is known about its maintenance and transmission in species-rich areas or about the potential role of domestic dog vaccination as a means of reducing disease threats to wildlife. We address these questions by analyzing a long-term serological dataset of CDV in lions and domestic dogs from Tanzania's Serengeti ecosystem. Using a Bayesian state-space model, we show that dynamics of CDV have changed considerably over the past three decades. Initially, peaks of CDV infection in dogs preceded those in lions, suggesting that spill-over from dogs was the main driver of infection in wildlife. However, despite dog-to-lion transmission dominating cross-species transmission models, infection peaks in lions became more frequent and asynchronous from those in dogs, suggesting that other wildlife species may play a role in a potentially complex maintenance community. Widespread mass vaccination of domestic dogs reduced the probability of infection in dogs and the size of outbreaks but did not prevent transmission to or peaks of infection in lions. This study demonstrates the complexity of CDV dynamics in natural ecosystems and the value of long-term, large-scale datasets for investigating transmission patterns and evaluating disease control strategies.
Asunto(s)
Animales Domésticos , Animales Salvajes , Virus del Moquillo Canino/patogenicidad , Morbillivirus/patogenicidad , Animales , Teorema de Bayes , Moquillo/transmisión , Moquillo/virología , Virus del Moquillo Canino/fisiología , Perros , Leones , Morbillivirus/fisiologíaRESUMEN
More than 100 years of research has now been conducted into the prevention, control and elimination of rabies with safe and highly efficacious vaccines developed for use in human and animal populations. Domestic dogs are a major reservoir for rabies, and although considerable advances have been made towards the elimination and control of canine rabies in many parts of the world, the disease continues to kill tens of thousands of people every year in Africa and Asia. Policy efforts are now being directed towards a global target of zero human deaths from dog-mediated rabies by 2030 and the global elimination of canine rabies. Here we demonstrate how research provides a cause for optimism as to the feasibility of these goals through strategies based around mass dog vaccination. We summarize some of the pragmatic insights generated from rabies epidemiology and dog ecology research that can improve the design of dog vaccination strategies in low- and middle-income countries and which should encourage implementation without further delay. We also highlight the need for realism in reaching the feasible, although technically more difficult and longer-term goal of global elimination of canine rabies. Finally, we discuss how research on rabies has broader relevance to the control and elimination of a suite of diseases of current concern to human and animal health, providing an exemplar of the value of a 'One Health' approach.
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Países en Desarrollo , Erradicación de la Enfermedad , Enfermedades de los Perros/prevención & control , Vacunas Antirrábicas/uso terapéutico , Rabia/prevención & control , África , Animales , Asia , Enfermedades de los Perros/transmisión , Perros , Humanos , Rabia/mortalidad , Rabia/transmisión , Vacunas Antirrábicas/provisión & distribuciónRESUMEN
BACKGROUND: Dogs are ubiquitous in human society and attempts to manage their populations are common to most countries. Managing dog populations is achieved through a range of interventions to suit the dog population dynamics and dog ownership characteristics of the location, with a number of potential impacts or goals in mind. Impact assessment provides the opportunity for interventions to identify areas of inefficiencies for improvement and build evidence of positive change. METHODS: This scoping review collates 26 studies that have assessed the impacts of dog population management interventions. RESULTS: It reports the use of 29 indicators of change under 8 categories of impact and describes variation in the methods used to measure these indicators. CONCLUSION: The relatively few published examples of impact assessment in dog population management suggest this field is in its infancy; however this review highlights those notable exceptions. By describing those indicators and methods of measurement that have been reported thus far, and apparent barriers to efficient assessment, this review aims to support and direct future impact assessment.
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Perros , Bienestar del Animal , Animales , Animales Salvajes , Conservación de los Recursos Naturales , Control de Plagas , Regulación de la Población , Dinámica PoblacionalRESUMEN
Katie Hampson and colleagues describe their experience of developing and deploying a large-scale rabies surveillance system based on mobile phones in southern Tanzania.
Asunto(s)
Mordeduras y Picaduras/virología , Teléfono Celular , Control de Enfermedades Transmisibles/instrumentación , Brotes de Enfermedades/prevención & control , Vacunas Antirrábicas/administración & dosificación , Rabia/prevención & control , Telemedicina/instrumentación , Atención a la Salud , Humanos , Esquemas de Inmunización , Vigilancia de la Población , Desarrollo de Programa , Evaluación de Programas y Proyectos de Salud , Rabia/diagnóstico , Rabia/epidemiología , Rabia/transmisión , Rabia/virología , Tanzanía/epidemiología , Factores de Tiempo , Resultado del Tratamiento , VacunaciónRESUMEN
BACKGROUND: The annual mortality rate of human rabies in rural Africa is 3.6 deaths per 100 000 persons. Rabies can be prevented with prompt postexposure prophylaxis, but this is costly and often inaccessible in rural Africa. Because 99% of human exposures occur through rabid dogs, canine vaccination also prevents transmission of rabies to humans. OBJECTIVE: To evaluate the cost-effectiveness of rabies control through annual canine vaccination campaigns in rural sub-Saharan Africa. DESIGN: We model transmission dynamics in dogs and wildlife and assess empirical uncertainty in the biological variables to make probability-based evaluations of cost-effectiveness. DATA SOURCES: Epidemiologic variables from a contact-tracing study and literature and cost data from ongoing vaccination campaigns. TARGET POPULATION: Two districts of rural Tanzania: Ngorongoro and Serengeti. TIME HORIZON: 10 years. PERSPECTIVE: Health policymaker. INTERVENTION: Vaccination coverage ranging from 0% to 95% in increments of 5%. OUTCOME MEASURES: Life-years for health outcomes and 2010 U.S. dollars for economic outcomes. RESULTS OF BASE-CASE ANALYSIS: Annual canine vaccination campaigns were very cost-effective in both districts compared with no canine vaccination. In Serengeti, annual campaigns with as much as 70% coverage were cost-saving. RESULTS OF SENSITIVITY ANALYSIS: Across a wide range of variable assumptions and levels of societal willingness to pay for life-years, the optimal vaccination coverage for Serengeti was 70%. In Ngorongoro, although optimal coverage depended on willingness to pay, vaccination campaigns were always cost-effective and lifesaving and therefore preferred. LIMITATION: Canine vaccination was very cost-effective in both districts, but there was greater uncertainty about the optimal coverage in Ngorongoro. CONCLUSION: Annual canine rabies vaccination campaigns conferred extraordinary value and dramatically reduced the health burden of rabies. PRIMARY FUNDING SOURCE: National Institutes of Health.
Asunto(s)
Enfermedades de los Perros/prevención & control , Enfermedades de los Perros/transmisión , Vacunas Antirrábicas/economía , Rabia/prevención & control , Vacunación/economía , Animales , Mordeduras y Picaduras/complicaciones , Análisis Costo-Beneficio , Perros , Humanos , Modelos Estadísticos , Rabia/epidemiología , Rabia/transmisión , Rabia/veterinaria , Población Rural , Tanzanía/epidemiologíaRESUMEN
We describe a statistical framework for reconstructing the sequence of transmission events between observed cases of an endemic infectious disease using genetic, temporal and spatial information. Previous approaches to reconstructing transmission trees have assumed all infections in the study area originated from a single introduction and that a large fraction of cases were observed. There are as yet no approaches appropriate for endemic situations in which a disease is already well established in a host population and in which there may be multiple origins of infection, or that can enumerate unobserved infections missing from the sample. Our proposed framework addresses these shortcomings, enabling reconstruction of partially observed transmission trees and estimating the number of cases missing from the sample. Analyses of simulated datasets show the method to be accurate in identifying direct transmissions, while introductions and transmissions via one or more unsampled intermediate cases could be identified at high to moderate levels of case detection. When applied to partial genome sequences of rabies virus sampled from an endemic region of South Africa, our method reveals several distinct transmission cycles with little contact between them, and direct transmission over long distances suggesting significant anthropogenic influence in the movement of infected dogs.
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Enfermedades Transmisibles/epidemiología , Transmisión de Enfermedad Infecciosa/estadística & datos numéricos , Métodos Epidemiológicos , Rabia/epidemiología , Animales , Secuencia de Bases , Teorema de Bayes , Enfermedades Transmisibles/transmisión , Enfermedades Transmisibles/veterinaria , Perros , Modelos Biológicos , Datos de Secuencia Molecular , Rabia/transmisión , Rabia/veterinaria , Virus de la Rabia/genética , Sudáfrica , TiempoRESUMEN
The ability of influenza A viruses (IAVs) to cross species barriers and evade host immunity is a major public health concern. Studies on the phylodynamics of IAVs across different scales - from the individual to the population - are essential for devising effective measures to predict, prevent or contain influenza emergence. Understanding how IAVs spread and evolve during outbreaks is critical for the management of epidemics. Reconstructing the transmission network during a single outbreak by sampling viral genetic data in time and space can generate insights about these processes. Here, we obtained intra-host viral sequence data from horses infected with equine influenza virus (EIV) to reconstruct the spread of EIV during a large outbreak. To this end, we analyzed within-host viral populations from sequences covering 90% of the infected yards. By combining gene sequence analyses with epidemiological data, we inferred a plausible transmission network, in turn enabling the comparison of transmission patterns during the course of the outbreak and revealing important epidemiological features that were not apparent using either approach alone. The EIV populations displayed high levels of genetic diversity, and in many cases we observed distinct viral populations containing a dominant variant and a number of related minor variants that were transmitted between infectious horses. In addition, we found evidence of frequent mixed infections and loose transmission bottlenecks in these naturally occurring populations. These frequent mixed infections likely influence the size of epidemics.
Asunto(s)
Coinfección/transmisión , Brotes de Enfermedades , Enfermedades de los Caballos/transmisión , Subtipo H3N8 del Virus de la Influenza A/genética , Infecciones por Orthomyxoviridae/transmisión , Animales , Coinfección/epidemiología , Coinfección/genética , Variación Genética , Enfermedades de los Caballos/epidemiología , Enfermedades de los Caballos/genética , Caballos , Subtipo H3N8 del Virus de la Influenza A/inmunología , Mucosa Nasal/virología , Infecciones por Orthomyxoviridae/epidemiología , Infecciones por Orthomyxoviridae/genética , ARN Viral/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Emergency vaccinations and culling failed to contain an outbreak of rabies in Bali, Indonesia, during 2008-2009. Subsequent island-wide mass vaccination (reaching 70% coverage, >200,000 dogs) led to substantial declines in rabies incidence and spread. However, the incidence of dog bites remains high, and repeat campaigns are necessary to eliminate rabies in Bali.
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Mordeduras y Picaduras/epidemiología , Brotes de Enfermedades , Enfermedades de los Perros/epidemiología , Vacunación Masiva/estadística & datos numéricos , Virus de la Rabia/fisiología , Rabia/veterinaria , Animales , Mordeduras y Picaduras/virología , Enfermedades de los Perros/prevención & control , Enfermedades de los Perros/transmisión , Enfermedades de los Perros/virología , Perros , Humanos , Incidencia , Indonesia/epidemiología , Rabia/epidemiología , Rabia/prevención & control , Rabia/virología , Vacunas Antirrábicas/administración & dosificación , Vacunas Antirrábicas/inmunología , Virus de la Rabia/aislamiento & purificación , Estudios RetrospectivosRESUMEN
Understanding how entire ecosystems maintain stability in the face of climatic and human disturbance is one of the most fundamental challenges in ecology. Theory suggests that a crucial factor determining the degree of ecosystem stability is simply the degree of synchrony with which different species in ecological food webs respond to environmental stochasticity. Ecosystems in which all food-web pathways are affected similarly by external disturbance should amplify variability in top carnivore abundance over time due to population interactions, whereas ecosystems in which a large fraction of pathways are nonresponsive or even inversely responsive to external disturbance will have more constant levels of abundance at upper trophic levels. To test the mechanism underlying this hypothesis, we used over half a century of demographic data for multiple species in the Serengeti (Tanzania) ecosystem to measure the degree of synchrony to variation imposed by an external environmental driver, the El Niño Southern Oscillation (ENSO). ENSO effects were mediated largely via changes in dry-season vs. wet-season rainfall and consequent changes in vegetation availability, propagating via bottom-up effects to higher levels of the Serengeti food web to influence herbivores, predators and parasites. Some species in the Serengeti food web responded to the influence of ENSO in opposite ways, whereas other species were insensitive to variation in ENSO. Although far from conclusive, our results suggest that a diffuse mixture of herbivore responses could help buffer top carnivores, such as Serengeti lions, from variability in climate. Future global climate changes that favor some pathways over others, however, could alter the effectiveness of such processes in the future.
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El Niño Oscilación del Sur , Cadena Alimentaria , Conducta Predatoria , África , Animales , Antílopes , Aves , Mamíferos , Plantas , Dinámica Poblacional , Lluvia , Estaciones del Año , Factores de TiempoRESUMEN
Control measures for canine rabies include vaccination and reducing population density through culling or sterilization. Despite the evidence that culling fails to control canine rabies, efforts to reduce canine population density continue in many parts of the world. The rationale for reducing population density is that rabies transmission is density-dependent, with disease incidence increasing directly with host density. This may be based, in part, on an incomplete interpretation of historical field data for wildlife, with important implications for disease control in dog populations. Here, we examine historical and more recent field data, in the context of host ecology and epidemic theory, to understand better the role of density in rabies transmission and the reasons why culling fails to control rabies. We conclude that the relationship between host density, disease incidence and other factors is complex and may differ between species. This highlights the difficulties of interpreting field data and the constraints of extrapolations between species, particularly in terms of control policies. We also propose that the complex interactions between dogs and people may render culling of free-roaming dogs ineffective irrespective of the relationship between host density and disease incidence. We conclude that vaccination is the most effective means to control rabies in all species.
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Enfermedades de los Perros/prevención & control , Rabia/veterinaria , Animales , Enfermedades de los Perros/epidemiología , Perros , Salud Global , Humanos , Densidad de Población , Rabia/epidemiología , Rabia/prevención & controlRESUMEN
Rabies is a lethal zoonotic disease mainly transmitted to humans by dog bites. The purpose of this study was to assess the efficacy of rabies control policies in Japan, which resulted in the elimination of the disease from the country in 1957. Using historical records from the Kanto region (Chiba, Kanagawa, Saitama and Tokyo Prefectures) between 1947 and 1956 where the final canine cases were recorded, we undertook a descriptive epidemiological study, applying spatio-temporal scan statistics using SaTScan and estimating the effective reproduction number (Rt ) for the clusters and each prefecture using the growth rates. There were 1,567 dog rabies and 161 human rabies cases recorded during this period. Vaccination coverage in registered dogs was over 70% after 1951, with much lower coverage in free-roaming and unregistered dogs. Eight clusters of dog rabies cases were identified: the first appeared in 1947 in Tokyo and was linked to three further clusters in peripheral prefectures between 1947 and 1951. Three more clusters occurred in Tokyo again between 1952 and 1954, and the last cluster was in Tokyo and Kanagawa between 1955 and 1956. Rt in the first cluster was 1.68, and Rt values in the others ranged between 1.18 and 1.86, with an exception of 4.05 in the smallest cluster in Tokyo in 1952 (10 cases). The moving average of Rt coincided with the clusters. As dog vaccination and dog management progressed, and the number of dog rabies cases declined, the moving average of Rt declined to below 1. Delays in the implementation of dog management policies in Kanagawa may have prolonged this last outbreak. These results demonstrate the effectiveness of coordinated control policy involving dog vaccination and management of free-roaming dog populations for rabies elimination.
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Enfermedades de los Perros , Vacunas Antirrábicas , Rabia , Perros , Humanos , Animales , Japón/epidemiología , Rabia/epidemiología , Rabia/prevención & control , Rabia/veterinaria , Enfermedades de los Perros/epidemiología , Enfermedades de los Perros/prevención & control , Vacunación/veterinaria , Brotes de EnfermedadesRESUMEN
Many rabies endemic-countries have recognized rabies as a public health problem that can be eliminated. As a result, some countries have started implementing small-scale vaccination programs with the aim of scaling them up. Post-vaccination serological monitoring is crucial to assess the efficacy of these programs. The recommended serological tests, the rapid fluorescent focus inhibition test, and the fluorescent antibody virus neutralization (FAVN) are accurate; however, the procedures require considerable expertise and must be carried out in high containment facilities, which are often not available in rabies endemic countries. Given these constraints, enzyme linked immunosorbent assays (ELISAs) have been considered as alternative methods to neutralization tests. This is the first study to evaluate, under field conditions, the performance of the commercial rabies indirect-ELISA (iELISA), the PlateliaTM Rabies II kit ad usum Veterinarium kit, using sera from domestic dogs. Serum samples were collected from two groups of community dogs in northern Tanzania: i) dogs with no history of vaccination against rabies (n = 100) and ii) dogs vaccinated with the Nobivac Canine Rabies® vaccine (n = 101) four weeks previously. When compared to the gold standard FAVN test, the iELISA was found to be 99% specific and 98% sensitive and there was a significant correlation between the two tests (p < 0.001, r = 0.92). Given these findings, we conclude that the PlateliaTM Rabies II kit ad usum Veterinarium can be considered a valuable tool for the rapid assessment of vaccination status of animals in vaccination programs.
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Enfermedades de los Perros , Vacunas Antirrábicas , Virus de la Rabia , Rabia , Animales , Perros , Rabia/diagnóstico , Rabia/prevención & control , Rabia/veterinaria , Anticuerpos Antivirales , Sensibilidad y Especificidad , Ensayo de Inmunoadsorción Enzimática/métodos , Factores Inmunológicos , Vacunación , Enfermedades de los Perros/diagnóstico , Enfermedades de los Perros/prevención & controlRESUMEN
Abstract: Sustained vaccination coverage of domestic dog populations can interrupt rabies transmission. However, challenges remain including low dog owner participation, high operational costs associated with current (centralized and annually delivered (pulse)) approaches and high dog population turnover. To address these challenges an alternative (community-based continuous mass dog vaccination (CBC-MDV)) approach was designed. We investigated the potential for successful normalization of CBC-MDV into routine practice within the context of local communities and the veterinary system of Tanzania. Methods: In a process evaluation of a pilot implementation of CBC-MDV, we conducted in-depth interviews with implementers and community leaders (n = 24), focus group discussion with implementers and community members (n = 12), and non-participant observation (n = 157 h) of delivery of the intervention components. We analyzed these data thematically drawing on the normalization process theory, to assess factors affecting implementation and integration. Main findings: Implementers and community members clearly understood the values and benefits of the CBC-MDV, regarding it as an improvement over the pulse strategy. They had a clear understanding of what was required to enact CBC-MDV and considered their own involvement to be legitimate. The approach fitted well into routine schedules of implementers and the context (infrastructure, skill sets and policy). Implementers and community members positively appraised CBC-MDV in terms of its perceived impact on rabies and recommended its use across the country. Implementers and community members further believed that vaccinating dogs free of charge was critical and made community mobilization easier. However, providing feedback to communities and involving them in evaluating outcomes of vaccination campaigns were reported to have not been done. Local politics was cited as a barrier to collaboration between implementers and community leaders. Conclusion: This work suggests that CBC-MDV has the potential to be integrated and sustained in the context of Tanzania. Involving communities in design, delivery and monitoring of CBC-MDV activities could contribute to improving and sustaining its outcomes.
RESUMEN
Genomic data can be used to track the transmission and geographic spread of infectious diseases. However, the sequencing capacity required for genomic surveillance remains limited in many low- and middle-income countries (LMICs), where dog-mediated rabies and/or rabies transmitted by wildlife such as vampire bats pose major public health and economic concerns. We present here a rapid and affordable sample-to-sequence-to-interpretation workflow using nanopore technology. Protocols for sample collection and the diagnosis of rabies are briefly described, followed by details of the optimized whole genome sequencing workflow, including primer design and optimization for multiplex polymerase chain reaction (PCR), a modified, low-cost sequencing library preparation, sequencing with live and offline base calling, genetic lineage designation, and phylogenetic analysis. Implementation of the workflow is demonstrated, and critical steps are highlighted for local deployment, such as pipeline validation, primer optimization, inclusion of negative controls, and the use of publicly available data and genomic tools (GLUE, MADDOG) for classification and placement within regional and global phylogenies. The turnaround time for the workflow is 2-3 days, and the cost ranges from $25 per sample for a 96 sample run to $80 per sample for a 12 sample run. We conclude that setting up rabies virus genomic surveillance in LMICs is feasible and can support progress toward the global goal of zero dog-mediated human rabies deaths by 2030, as well as enhanced monitoring of wildlife rabies spread. Moreover, the platform can be adapted for other pathogens, helping to build a versatile genomic capacity that contributes to epidemic and pandemic preparedness.