Mathematical Modelling of Transmission Dynamics of Anthrax in Human and Animal Population.

Anthrax is an infectious disease that can be categorised under zoonotic diseases. It is caused by the bacteria known as Bacillus anthraces. Anthrax is one of the most leading causes of deaths in domestic and wild animals. In this paper, we develop and investigated a mathematical model for the transmission dynamics of the disease. Ordinary differential equations were formulated from the mathematical model. We performed the quantitative and qualitative analysis of the model to explain the transmission dynamics of the anthrax disease. We analysed and determined the model’s steady states solutions. The disease-free equilibrium of the anthrax model is analysed for locally asymptotic stability and the associated epidemic basic reproduction number. The model’s disease free equilibrium has shown to be locally asymptotically stable when the basic reproductive number is less than unity. The model is found to exhibit the existence of multiple endemic equilibria. Sensitivity analysis was performed on the model’s parameters to investigate the most sensitive parameters in the dynamics of the diseases. Keywords: Anthrax model, Basic reproductive number, Asymptotic stability, Endemic equilibrium, Sensitivity analysis

One health research in Northern Tanzania – challenges and progress

East Africa has one of the world’s fastest growing human populations—many of whom are dependent on livestock—as well as some of the world’s largest wildlife populations. Humans, livestock, and wildlife often interact closely, intimately linking human, animal, and environmental health. The concept of One Health captures this interconnectedness, including the social structures and beliefs driving interactions between species and their environments. East African policymakers and researchers are recognising and encouraging One Health research, with both groups increasingly playing a leading role in this subject area. One Health research requires interaction between scientists from different disciplines, such as the biological and social sciences and human and veterinary medicine. Different disciplines draw on norms, methodologies, and terminologies that have evolved within their respective institutions and that may be distinct from or in conflict with one another. These differences impact interdisciplinary research, both around theoretical and methodological approaches and during project operationalisation. We present experiential knowledge gained from numerous ongoing projects in northern Tanzania, including those dealing with bacterial zoonoses associated with febrile illness, foodborne disease, and anthrax. We use the examples to illustrate differences between and within social and biological sciences and between industrialised and traditional societies, for example, with regard to consenting procedures or the ethical treatment of animals. We describe challenges encountered in ethical approval processes, consenting procedures, and field and laboratory logistics and offer suggestions for improvement. While considerable investment of time in sensitisation, communication, and collaboration is needed to overcome interdisciplinary challenges inherent in One Health research, this can yield great rewards in paving the way for successful implementation of One Health projects. Furthermore, continued investment in African institutions and scientists will strengthen the role of East Africa as a world leader in One Health research

Permafrost dynamics and the risk of anthrax transmission: a modelling study

A recent outbreak of anthrax disease, severely affecting reindeer herds in Siberia, has been reportedly associated to the presence of infected carcasses or spores released from the active layer over permafrost, which is thawing and thickening at increasing rates, thus underlying the re-emerging nature of this pathogen in the Arctic region because of warming temperatures. Anthrax is a global zoonotic and epizootic disease, with a high case-fatality ratio in infected animals. Its transmission is mediated by environmental contamination through highly resistant spores which can persist in the soil for several decades. Here we develop and analyze a new epidemiological model for anthrax transmission that is specifically tailored to the Arctic environmental conditions. The model describes transmission dynamics including also herding practices (e.g. seasonal grazing) and the role of the active layer over permafrost acting as a long-term storage of spores that could be viable for disease transmission during thawing periods. Model dynamics are investigated through linear stability analysis, Floquet theory for periodically forced systems, and a series of simulations with realistic forcings. Results show how the temporal variability of grazing and active layer thawing may influence the dynamics of anthrax disease and, specifically, favor sustained pathogen transmission. Particularly warm years, favoring deep active layers, are shown to be associated with an increase risk of anthrax outbreaks, and may also foster infections in the following years. Our results enable preliminary insights into measures (e.g. changes in herding practice) that may be adopted to decrease the risk of infection and lay the basis to possibly establish optimal procedures for preventing transmission; furthermore, they elicit the need of further investigations and observation campaigns focused on anthrax dynamics in the Arctic environment

ANTHRAX MODELS INVOLVING IMMUNOLOGY, EPIDEMIOLOGY AND CONTROLS

This dissertation is divided in two parts. Chapters 2 and 3 consider the use of optimal control theory in an anthrax epidemiological model. Models consisting system of ordinary differential equations (ODEs) and partial differential differential equations (PDEs) are considered to describe the dynamics of infection spread. Two controls, vaccination and disposal of infected carcasses, are considered and their optimal management strategies are investigated. Chapter 4 consists modeling early host pathogen interaction in an inhalational anthrax infection which consists a system of ODEs that describes early dynamics of bacteria-phagocytic cell interaction associated to an inhalational anthrax infection. First we consider a model with system of four ODEs describing dynamics between animal population and the anthrax spores. Stability analysis is performed for our system and basis reproduction number is calculated for the system. A system of ODEs modeling an anthrax epizootic is formulated. Two controls representing vaccination animals and disposal of infected carcasses are investigated in order to minimize the number of infected animals, number of infected carcasses and the cost of vaccination and carcass disposal. Model parameters are estimated using outbreak data, and some numerical results for the optimal control problem are presented. We extend the model into the system of PDEs coupled with ODEs to include animal movement within a region. both time and space dependent controls are applied into this hybrid system. Existence and uniqueness results are established for weak solutions of the System. The existence of an optimal control pair and the characterization of the controls are derived from corresponding adjoint systems. Numerical results are completed to illustrate various scenarios. The immunological model in Chapter 4 consists of a system of ODEs to describes early host pathogen interaction. The modeling assumptions are close to an experimental setting and the model parameters are estimated using these experimental data. Our goal is to understand the early process such as the spore phagocytosis, spore germination, killing of the germinated spores and their replication. Different functional forms for germination and killing are considered and two different models based on bacterial stage are considered to better fit the experimental data

Transmission modelling of environmentally persistent zoonotic diseases: a systematic review.

Transmission of many infectious diseases depends on interactions between humans, animals, and the environment. Incorporating these complex processes in transmission dynamic models can help inform policy and disease control interventions. We identified 20 diseases involving environmentally persistent pathogens (ie, pathogens that survive for more than 48 h in the environment and can cause subsequent human infections), of which indirect transmission can occur from animals to humans via the environment. Using a systematic approach, we critically appraised dynamic transmission models for environmentally persistent zoonotic diseases to quantify traits of models across diseases. 210 transmission modelling studies were identified and most studies considered diseases of domestic animals or high-income settings, or both. We found that less than half of studies validated their models to real-world data, and environmental data on pathogen persistence was rarely incorporated. Model structures varied, with few studies considering the animal-human-environment interface of transmission in the context of a One Health framework. This Review highlights the need for more data-driven modelling of these diseases and a holistic One Health approach to model these pathogens to inform disease prevention and control strategies

Zoonoses (Project 1): Wildlife/domestic livestock interactions

The objective of this study was to synthesise the best available scientific knowledge about zoonotic disease transmission through livestock and wildlife interaction (direct or indirect), with emphasis on risk factors, drivers and trajectories of transmission, as well as promising interventions for controlling important zoonoses, based on managing the interaction between domestic livestock and wildlife. A multi-disciplinary team from the International Livestock Research Institute, Kenya, and the Royal Veterinary College, United Kingdom, with expertise in zoonoses, epidemiology, socio-economics, and wildlife, undertook the review. A database of important zoonoses was compiled and used to develop a list of priority zoonoses with a livestock-wildlife interface for developing countries. Spatial relationships between important zoonoses and land use and human population density were explored. A systematic review was carried out focussing on: disease transmission routes, risk factors for disease transmission, drivers of wildlife-livestock interactions, pathogens of wildlife capable of recombining with organisms in livestock, wildlife species that are potential sources of zoonotic pathogens, production and socio-economic factors influencing the risk of transmission, and risk management and control interventions

Linkages between animal and human health sentinel data

INTRODUCTION: In order to identify priorities for building integrated surveillance systems that effectively model and predict human risk of zoonotic diseases, there is a need for improved understanding of the practical options for linking surveillance data of animals and humans. We conducted an analysis of the literature and characterized the linkage between animal and human health data. We discuss the findings in relation to zoonotic surveillance and the linkage of human and animal data. METHODS: The Canary Database, an online bibliographic database of animal-sentinel studies was searched and articles were classified according to four linkage categories. RESULTS: 465 studies were identified and assigned to linkage categories involving: descriptive, analytic, molecular, or no human outcomes of human and animal health. Descriptive linkage was the most common, whereby both animal and human health outcomes were presented, but without quantitative linkage between the two. Rarely, analytic linkage was utilized in which animal data was used to quantitatively predict human risk. The other two categories included molecular linkage, and no human outcomes, which present health outcomes in animals but not humans. DISCUSSION: We found limited use of animal data to quantitatively predict human risk and listed the methods from the literature that performed analytic linkage. The lack of analytic linkage in the literature might not be solely related to technological barriers including access to electronic database, statistical software packages, and Geographical Information System (GIS). Rather, the problem might be from a lack of understanding by researchers of the importance of animal data as a 'sentinel' for human health. Researchers performing zoonotic surveillance should be aware of the value of animal-sentinel approaches for predicting human risk and consider analytic methods for linking animal and human data. Qualitative work needs to be done in order to examine researchers' decisions in linkage strategies between animal and human data

The Epidemiological Framework for Biological Invasions (EFBI): An interdisciplinary foundation for the assessment of biosecurity threats

Emerging microparasite (e.g. viruses, bacteria, protozoa and fungi) epidemics and the introduction of non-native pests and weeds are major biosecurity threats worldwide. The likelihood of these threats is often estimated from probabilities of their entry, establishment, spread and ease of prevention. If ecosystems are considered equivalent to hosts, then compartment disease models should provide a useful framework for understanding the processes that underpin non-native species invasions. To enable greater cross-fertilisation between these two disciplines, the Epidemiological Framework for Biological Invasions (EFBI) is developed that classifies ecosystems in relation to their invasion status: Susceptible, Exposed, Infectious and Resistant. These states are linked by transitions relating to transmission, latency and recovery. This viewpoint differs markedly from the species-centric approaches often applied to non-native species. It allows generalisations from epidemiology, such as the force of infection, the basic reproductive ratio R0, super-spreaders, herd immunity, cordon sanitaire and ring vaccination, to be discussed in the novel context of non-native species and helps identify important gaps in the study of biological invasions. The EFBI approach highlights several limitations inherent in current approaches to the study of biological invasions including: (i) the variance in non-native abundance across ecosystems is rarely reported; (ii) field data rarely (if ever) distinguish source from sink ecosystems; (iii) estimates of the susceptibility of ecosystems to invasion seldom account for differences in exposure to non-native species; and (iv) assessments of ecosystem susceptibility often confuse the processes that underpin patterns of spread within -and between- ecosystems. Using the invasion of lakes as a model, the EFBI approach is shown to present a new biosecurity perspective that takes account of ecosystem status and complements demographic models to deliver clearer insights into the dynamics of biological invasions at the landscape scale. It will help to identify whether management of the susceptibility of ecosystems, of the number of vectors, or of the diversity of pathways (for movement between ecosystems) is the best way of limiting or reversing the population growth of a non-native species. The framework can be adapted to incorporate increasing levels of complexity and realism and to provide insights into how to monitor, map and manage biological invasions more effectively

One Arctic - One Health

One Health takes a multidisciplinary approach to health risks and risk mitigation for humans, animals, plants and the environment, with the understanding that human health welfare is dependent on ecosystem health. The U.S. and Canada started the One Health project under the Sustainable Development Working Group (SDWG) of the Arctic Council in 2015, Finland joined the project as a colead in 2017. This report is a summary of the Finnish activities and achievements in the One Arctic - One Health project during the Finnish Chairmanship of the Arctic Council. The main actions included the One Arctic - One Health conference in Oulu, establishment of the TremArctic network, and two published Systematic Review papers and two manuscripts. There were also joint sessions and presentations in scientific conferences, seminars and workshops, and joint meetings and collaboration with the other Arctic Council Working Groups, the University of the Arctic, other organisations, and scientific projects. The report concludes with some updated proposals for further work, based on previous works and reflecting progress over the past two years. The Finnish One Arctic - One Health team consisted of scientists from the University of Oulu, National Institute for Health and Welfare (THL), University of Helsinki and the Finnish Food Authority. This work was supported by the grant of the Ministry for Foreign Affairs of Finland.Yhteisen terveyden (One Health) perusajatus on, että ihmisten, eläinten, kasvien ja ympäristön terveys on toisistaan riippuvaista, ainakin niin, että sairaassa ympäristössä ei ihminenkään voi olla hyvinvoiva. Yhdysvaltain johtaessa puhetta Arktisessa neuvostossa, USA ja Kanada aloittivat kestävän kehityksen työryhmän (SDWG) alaisuudessa One Health -hankkeen, jonka johtoon Suomi liittyi toimiessaan Arktisen neuvoston puheenjohtajana 2017-2019. Tämä raportti on yhteenveto Suomen toimista ja saavutuksista puheenjohtajakaudellaan. Tärkeimmät toimet olivat One Arctic - One Health -konferenssi Oulussa, TremArctic-verkoston toiminnan aloittaminen, kaksi julkaistua laajaa systemaattista katsausta ja kaksi käsikirjoitusta. Lisäksi Suomen työryhmä osallistui tieteellisiin konferensseihin, seminaareihin ja työpajoihin, sekä yhteisiin kokouksiin ja muuhun yhteistyöhön Arktisen neuvoston muiden työryhmien kanssa. Raportti sisältää myös päivitettyjä jatkotoimenpide-ehdotuksia, jotka perustuvat aikaisempaan työhön ja viimeisten kahden vuoden aikana tapahtuneeseen kehitykseen. Suomen Yksi Arktis – yhteinen terveys -työryhmä koostui asiantuntijoista Oulun yliopistosta, Terveyden ja hyvinvoinnin laitoksesta, Helsingin yliopistosta ja Ruokavirastosta. Hanketta rahoitti Suomen ulkoministeriö.Grundprincipen till One Health -tänkandet är att människohälsa, djurhälsa, planthälsa och ekosystemhälsa är nära besläktade. I alla fall så att människans välfärd kräver frisk natur. Under det amerikanska ordförandeskapet i Arktiska rådet inledde USA och Kanada One Health -projektet i regi av arbetsgruppen för hållbar utveckling (Sustainable Development Working Group, SDWG). Finland gick med i ledningen av projektet under Finland ordförandeskap 2017-2019. Denna rapport är en sammanfattning av finska åtgärder och resultat under Finlands ordförandeskap. De mest viktiga handlingarna var arrangerandet av One Arctic - One Health – konferensen i Uleåborg, startandet av TremArctic-nätverket, publiceringen av två systematiska litteraturöversikter och produceringen av två vetenskapliga manuskript. I tillägg deltog den finska arbetsgruppen i vetenskapliga konferenser, seminar och verkstäder med gemensamma sessioner och presentationer. Vidare hade man gemensamma möter samt annat samarbete med andra arbetsgrupper under Arktiska rådet. Rapporten innehåller också uppdaterade förslag till för ytterligare åtgärder baserade på tidigare arbeten och utvecklingen under Finland ordförandeskap. Finlands One Arctic – One Health - arbetsgrupp bestod av forskare från Uleåborgs universitet, Institutet för hälsa och välfärd, Helsingfors universitet, samt Livsmedelsverket. Projektet fick finansiering från det finska utrikesministeriet

One Health and zoonoses activities at 17 select international locations : Nay 2013-April 2014

Compiled by the One Health Office, Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention.Welcome to the third annual report of One Health and Zoonoses projects that the Centers for Disease Control and Prevention (CDC) is conducting at 17 international sites, including 15 countries, the World Organisation for Animal Health (OIE), and the United Nations Food and Agriculture Organization (FAO). The purpose of this Report is to facilitate communication, collaboration, and coordination of animal-human interface activities in order to maximize the impact of CDC's global presence. The Report is prepared by the One Health Office (OHO), National Center for Emerging and Infectious Diseases (NCEZID), CDC.Foreword -- Table of international One Health and zoonoses activities -- Country and International Organization Profiles: Bangladesh; China; Democratic Republic of the Congo; Egypt; Guatemala; India; Indonesia; Kazakhstan; Kenya; Nigeria; Republic of Georgia; South Africa; Thailand; Uganda; Vietnam; Food and Agriculture Organization of the United Nations; World Organisation for Animal Health -- Acronyms -- Table definitions -- AHI officer contact information