Serological investigation of vector-borne disease in dogs from rural areas of China

Objective:To evaluate the Anaplasma phagocytophilum(A.phagocytophilum),Ehrlichia canis(E.canis,Dirofilaria immitis(D.immitis)(canine heartworm),Borrelia burgdorferi(B.burgdorferi)infections in countryside dogs from Yunnan,Hainan and Anhui provinces.Methods:Serum samples were collected from 26 dogs in Yunnan.Hainan and Anhui provinces.The samples were tested using a commercial ELISA rapid diagnostic assay kit(SNAP^(?)4Dx^(?);IDEXX Laboratories,Inc.U.S.A.).Meaiiwliile,indirect immunofluorescence assay(IFA)recommended by WHO was conducted to delect IgG to A.phagocytophilum.Two methods were analyzed and compared.Results:The number of serologically positive dogs for IgG to A.phagocytophilum was only 2which was from Hainan province and none of the 26 dogs responded positive for E.canu.D.immitis(canine heartworm,and B.burgdorferi by ELISA rapid diagnostic method.The number of serologically positive dogs for IgG to A.phagocytophilum was 13(50%)by IFA method.Data of the two methods were analyzed by statistical software and the difference was statistically significant(P=0.002).Conclusions:It can be concluded that IFA method was more sensitive than ELISA rapid diagnostic method.However,we need conduct further and intensive epidemiology survey on tick-born diseases pathogens including.4.phagocytophilum,E.canis,D.immitis(canine heartworm),and B.burgdorferi which have public health significance.

Global Dynamic Analysis of a Vector-Borne Plant Disease Model with Discontinuous Treatment

This paper proposes a vector-borne plant disease model with discontinuous treatment strategies. Constructing Lyapunov function and applying non-smooth theory to analyze discontinuous differential equations, the basic reproductive number R0 is proved, which determines whether the plant disease will be extinct or not. If R0 R0 > 1 , there exists a unique endemic equilibrium which is globally stable. The numerical simulations are provided to verify our theoretical results, which indicate that after infective individuals reach some level, strengthening treatment measures is proved to be beneficial in controlling disease transmission.

Vector-borne diseases: Mosquito holobiont and novel methods for vector control

Female mosquitoes of several species require blood from warmblooded animals,including humans for the purpose of reproduction.In this process,several microbes residing in the salivary gland and midgut of mosquitoes also get transferred from one human individual to the other–a traditional model by which many vector-borne diseases(VBDs)get transmitted in the population through mosquitoes belonging to Anopheles,Aedes,Culex and other genera.

Effective Control Strategies on the Transmission Dynamics of a Vector-Borne Disease

In this paper, we have rigorously analyzed a model to find the effective control strategies on the transmission dynamics of a vector-borne disease. It is proved that the global dynamics of the disease are completely determined by the basic reproduction number. The numerical simulations (using MatLab and Maple) of the model reveal that the precautionary measures at the aquatic and adult stage decrease the number of new cases of dengue virus. Numerical simulation indicates that if we take the precautionary measures seriously then it would be more effective than even giving the treatment to the infected individuals.

An Agent-Based Model for Studying the Impact of Herd Mobility on the Spread of Vector-Borne Diseases: The Case of Rift Valley Fever (Ferlo Senegal)

Vector-borne diseases are highly sensitive to environment and to environmental changes. Rift Valley Fever (RFV) is a mosquito-borne zootic virus associated with severe diseases in human beings and economic consequences to livestock sector. Animal and human movements have a fundamental impact on RVF transmission. In recent years, there has been a growing interest in the use of mathematics and agent based models to represent and analyze the dynamic of RFV transmission. However, no previous study has taken into consideration animal herds’ mobility and precipitation factors to understand the disease spread. This limitation underlines the necessity to use computational model approach based on multi-agent system in the study of vector-borne diseases transmission and diffusion. In this paper, a multi-agent system combining conceptual model expressiveness is used to study animal herds’ mobility and the precipitation parameter impact on the Rift Valley Fever outbreak in Ferlo Barkedji in Northern Senegal. Simulation scenarios with various parameters, including rain quality, hosts, vectors, camp dispersal around ponds, etc., are unrolled. The different results we have obtained show that the evolution of the number of infected hosts and infected vectors depend on the degree of animal herds’ mobility and on precipitations. Our model provides a framework that permits predicting the spread of the disease associated with the mobility of animal herds.

Control of malaria and other vector-borne protozoan diseases in the tropics: enduring challenges despite considerable progress and achievements

Vector-borne protozoan diseases represent a serious public health challenge,especially in the tropics where poverty together with vector-favorable climates are the aggravating factors.Each of the various strategies currently employed to face these scourges is seriously inadequate.Despite enormous efforts,vaccines-which represent the ideal weapon against these parasitic diseases—are yet to be sufficiently developed and implemented.Chemotherapy and vector control are therefore the sole effective attempts to minimize the disease burden.Nowadays,both strategies are also highly challenged by the phenomenon of drug and insecticide resistance,which affects virtually all interventions currently used.The recently growing support from international organizations and governments of some endemic countries is warmly welcome,and should be optimally exploited in the various approaches to drug and insecticide research and development to overcome the burden of these prevalent diseases,especially malaria,leishmaniasis,Human African Trypanosomiasis(HAT),and Chagas disease.

Supporting and strengthening research on urban health interventions for the prevention and control of vector-borne and other infectious diseases of poverty:scoping reviews and research gap analysis

Background:More than half of the world’s population currently lives in urban settlements that grow both in size and number.By 2050,approximately 70%of the global population will be living in urban conglomerations,mainly in low-and middle-income countries.Mobility,poverty,different layers of inequalities as well as climate variability and change are some of the social and environmental factors that influence the exposure of human populations in urban settings to vector-borne diseases,which pose eminent public health threats.Accurate,consistent,and evidencebased interventions for prevention and control of vector-borne and other infectious diseases of poverty in urban settings are needed to implement innovative and cost-effective public policy and to promote inclusive and equitable urban health services.Main body:While there is growing awareness of vector-borne diseases epidemiology at the urban level,there is still a paucity of research and action being undertaken in this area,hindering evidence-based public health policy decisions and practice and strategies for active community engagement.This paper describes the collaboration and partnership of the Special Programme for Research and Training in Tropical Diseases(TDR)hosted by the World Health Organization(WHO)and the“VEctor boRne DiseAses Scoping reviews”(VERDAS)Research Consortium as they joined efforts in response to filling this gap in knowledge and evidence by supporting the development of a series of scoping reviews that highlight priority research gaps and policy implications to address vector-borne and other infectious diseases at the urban level.Conclusions:The set of scoping reviews proposed in this special issue presents a critical analysis of the state-of-the-art of research on urban health interventions for the prevention and control of vector-borne and other infectious diseases of poverty.The authors of the 6 reviews highlighted severe gaps in knowledge and identified organizational and theoretical limitations that need to be urgently tackled to improve cities preparedness and vector control response.The more pressing need at present is to ensure that more implementation research on vector-borne diseases in urban settings is conducted,addressing policy and practice implications and calling for more political commitment and social mobilization through adequate citizen engagement strategies.

Priorities and needs for research on urban interventions targeting vector-borne diseases: rapid review of scoping and systematic reviews

This paper highlights the critical importance of evidence on vector-borne diseases(VBD)prevention and control interventions in urban settings when assessing current and future needs,with a view to setting policy priorities that promote inclusive and equitable urban health services.Research should produce knowledge about policies and interventions that are intended to control and prevent VBDs at the population level and to reduce inequities.Such interventions include policy,program,and resource distribution approaches that address the social determinants of health and exert influence at organizational and system levels.

Support for research towards understanding the population health vulnerabilities to vector-borne diseases:increasing resilience under climate change conditions in Africa

Background:Diseases transmitted to humans by vectors account for 17%of all infectious diseases and remain significant public health problems.Through the years,great strides have been taken towards combatting vectorborne diseases(VBDs),most notably through large scale and coordinated control programmes,which have contributed to the decline of the global mortality attributed to VBDs.However,with environmental changes,including climate change,the impact on VBDs is anticipated to be significant,in terms of VBD-related hazards,vulnerabilities and exposure.While there is growing awareness on the vulnerability of the African continent to VBDs in the context of climate change,there is still a paucity of research being undertaken in this area,and impeding the formulation of evidence-based health policy change.Main body:One way in which the gap in knowledge and evidence can be filled is for donor institutions to support research in this area.The collaboration between the WHO Special Programme for Research and Training in Tropical Diseases(TDR)and the International Centre for Research and Development(IDRC)builds on more than 10 years of partnership in research capacity-building in the field of tropical diseases.From this partnership was born yet another research initiative on VBDs and the impact of climate change in the Sahel and sub-Saharan Africa.This paper lists the projects supported under this research initiative and provides a brief on some of the policy and good practice recommendations emerging from the ongoing implementation of the research projects.Conclusion:Data generated from the research initiative are expected to be uptaken by stakeholders(including communities,policy makers,public health practitioners and other relevant partners)to contribute to a better understanding of the impacts of social,environmental and climate change on VBDs(i.e.the nature of the hazard,vulnerabilities,exposure),and improve the ability of African countries to adapt to and reduce the effects of these changes in ways that benefit their most vulnerable populations.

Vector-borne disease and climate change adaptation in African dryland socialecological systems

Background:Drylands,which are among the biosphere's most naturally limiting and environmentally variable ecosystems,constitute three-quarters of the African continent.As a result,environmental sustainability and human development along with vector-borne disease(VBD)control historically have been especially challenging in Africa,particularly in the sub-Saharan and Sahelian drylands.Here,the VBD burden,food insecurity,environmental degradation,and social vulnerability are particularly severe.Changing climate can exacerbate the legion of environmental health threats in Africa,the social dimensions of which are now part of the international development agenda.Accordingly,the need to better understand the dynamics and complex coupling of populations and environments as exemplified by drylands is increasingly recognized as critical to the design of more sustainable interventions.Main body:This scoping review examines the challenge of vector-borne disease control in drylands with a focus on Africa,and the dramatic,ongoing environmental and social changes taking place.Dryland societies persisted and even flourished in the past despite changing climates,extreme and unpredictable weather,and marginal conditions for agriculture.Yet intrusive forces largely out of the control of traditional dryland societies,along with the negative impacts of globalization,have contributed to the erosion of dryland's cultural and natural resources.This has led to the loss of resilience underlying the adaptive capacity formerly widely exhibited among dryland societies.A growing body of evidence from studies of environmental and natural resource management demonstrates how,in light of dryland system's inherent complexity,these factors and top-down interventions can impede sustainable development and vector-borne disease control.Strengthening adaptive capacity through community-based,participatory methods that build on local knowledge and are tailored to local ecological conditions,hold the best promise of reversing current trends.Conclusions:A significant opportunity exists to simultaneously address the increasing threat of vector-borne diseases and climate change through methods aimed at strengthening adaptive capacity.The integrative framework and methods based on social-ecological systems and resilience theory offers a novel set of tools that allow multiple threats and sources of vulnerability to be addressed in combination.Integration of recent advances in vector borne disease ecology and wider deployment of these tools could help reverse the negative social and environmental trends currently seen in African drylands.

Interventions for vector-borne diseases focused on housing and hygiene in urban areas:a scoping review

Background:Over half the world’s human populations are currently at risk from vector-borne diseases(VBDs),and the heaviest burden is borne by the world’s poorest people,communities,and countries.The aim of this study was to conduct a review on VBD interventions relevant to housing and hygiene(including sanitation and waste management)in urban areas.Main body:We conducted a scoping review,which involved systematically searching peer-reviewed and grey literature published between 2000 and 2016 using five scientific databases and one database for grey literature.Different data extraction tools were used for data coding and extraction.We assessed the quality of each study using the Mixed Methods Appraisal Tool and extracted descriptive characteristics and data about implementation process and transferability from all studies using the Template for Intervention Description and Replication and ASTAIRE(a tool for analyzing the transferability of health promotion interventions)tools.We reviewed 44 studies.Overall,the studies were judged to be of high risk for bias.Our results suggest multifaceted interventions,particularly community-based interventions,have the potential to achieve wider and more sustained effects than do standard vertical single-component programs.The evaluations of multifaceted interventions tend to include integrated evaluations,using not only entomological indicators but also acceptability and sustainability indicators.Conclusions:This review highlighted the important need for higher quality research in VBDs and improved and standardized reporting of interventions.Significant research gaps were found regarding qualitative research and implementation research,and results highlighted the need for more interventions focus on sanitation and hygiene practices.

Climate drivers of vector-borne diseases in Africa and their relevance to control programmes

Background:Climate-based disease forecasting has been proposed as a potential tool in climate change adaptation for the health sector.Here we explore the relevance of climate data,drivers and predictions for vector-borne disease control efforts in Africa.Methods:Using data from a number of sources we explore rainfall and temperature across the African continent,from seasonality to variability at annual,multi-decadal and timescales consistent with climate change.We give particular attention to three regions defined as WHO-TDR study zones in Western,Eastern and Southern Africa.Our analyses include 1)time scale decomposition to establish the relative importance of year-to-year,decadal and long term trends in rainfall and temperature;2)the impact of the El Niño Southern Oscillation(ENSO)on rainfall and temperature at the Pan African scale;3)the impact of ENSO on the climate of Tanzania using high resolution climate products and 4)the potential predictability of the climate in different regions and seasons using Generalized Relative Operating Characteristics.We use these analyses to review the relevance of climate forecasts for applications in vector borne disease control across the continent.Results:Timescale decomposition revealed long term warming in all three regions of Africa-at the level of 0.1-0.3°C per decade.Decadal variations in rainfall were apparent in all regions and particularly pronounced in the Sahel and during the East African long rains(March-May).Year-to-year variability in both rainfall and temperature,in part associated with ENSO,were the dominant signal for climate variations on any timescale.Observed climate data and seasonal climate forecasts were identified as the most relevant sources of climate information for use in early warning systems for vector-borne diseases but the latter varied in skill by region and season.Conclusions:Adaptation to the vector-borne disease risks of climate variability and change is a priority for government and civil society in African countries.Understanding rainfall and temperature variations and trends at multiple timescales and their potential predictability is a necessary first step in the incorporation of relevant climate information into vector-borne disease control decision-making.

Impact,economic evaluation,and sustainability of integrated vector management in urban settings to prevent vector-borne diseases:a scoping review

Background:The control of vector-borne diseases(VBD)is one of the greatest challenges on the global health agenda.Rapid and uncontrolled urbanization has heightened the interest in addressing these challenges through an integrated vector management(IVM)approach.The aim was to identify components related to impacts,economic evaluation,and sustainability that might contribute to this integrated approach to VBD prevention.Main body:We conducted a scoping review of available literature(2000-2016)using PubMed,Web of Science,Cochrane,CINAHL,Econlit,LILACS,Global Health Database,Scopus,and Embase,as well as Tropical Diseases Bulletin,WHOLIS,WHO Pesticide Evaluation Scheme,and Google Scholar.MeSH terms and free-text terms were used.A data extraction form was used,including TIDieR and ASTAIRE.MMAT and CHEERS were used to evaluate quality.Of the 42 documents reviewed,30 were focused on dengue,eight on malaria,and two on leishmaniasis.More than a half of the studies were conducted in the Americas.Half used a quantitative descriptive approach(n=21),followed by cluster randomized controlled trials(n=11).Regarding impacts,outcomes were:a)use of measures for vector control;b)vector control;c)health measures;and d)social measures.IVM reduced breeding sites,the entomology index,and parasite rates.Results were heterogeneous,with variable magnitudes,but in all cases were favourable to the intervention.Evidence of IVM impacts on health outcomes was very limited but showed reduced incidence.Social outcomes were improved abilities and capacities,empowerment,and community knowledge.Regarding economic evaluation,only four studies performed an economic analysis,and intervention benefits outweighed costs.Costeffectiveness was dependent on illness incidence.The results provided key elements to analyze sustainability in terms of three dimensions(social,economic,and environmental),emphasizing the implementation of a community-focused eco-bio-social approach.Conclusions:IVM has an impact on reducing vector breeding sites and the entomology index,but evidence of impacts on health outcomes is limited.Social outcomes are improved abilities and capacities,empowerment,and community knowledge.Economic evaluations are scarce,and cost-effectiveness is dependent on illness incidence.Community capacity building is the main component of sustainability,together with collaboration,institutionalization,and routinization of activities.Findings indicate a great heterogeneity in the interventions and highlight the need for characterizing interventions rigorously to facilitate transferability.

Containment measures for emerging and re-emerging vector-borne and other infectious diseases of poverty in urban settings:a scoping review

Background:The emergence and re-emergence of vector-borne and other infectious diseases of poverty pose a threat to the health of populations living in urban and low-income settings.A detailed understanding of intervention strategies,including effectiveness of past outbreak containment,is necessary to improve future practices.The objective was to determine what is known about the effectiveness of containment measures for emerging and re-emerging vector-borne and other infectious diseases of poverty in urban settings and identify research gaps and implications for public health practice.Main body:We conducted a scoping review and systematically searched peer-reviewed and grey literature published between 2000 and 2016.Different data extraction tools were used for data coding and extraction,and data on implementation process and transferability were extracted from all studies.A quality assessment was conducted for each included study.We screened 205 full-text articles and reports for a total of 31 articles included in the review.The quality of the studies was generally low to moderate.The largest body of evidence concerned control activities for Ebola virus and dengue fever.The majority of interventions(87%)relied on multiple types of measures,which were grouped into four categories:1)healthcare provision;2)epidemiological investigation and/or surveillance;3)environmental or sanitary interventions;and 4)community-based interventions.The quality of the majority of studies(90%)was poor or moderate,and one-third of the studies did not provide a clear description of the outcomes and of the procedures and/or tools used for the intervention.Conclusions:Our results highlight the difficulty of establishing causation when assessing the effect of containment measures.Studies that extend beyond solely reporting on effectiveness and take into account the complexity of real-world settings are urgently needed.We recommend the allocation of research efforts to the evaluation of the implementation processes of interventions as well as their comprehensive and systematic description using validated checklists.

Bacterial Vector-Borne Plant Diseases:Unanswered Questions and Future Directions

Vector-borne plant diseases have significant ecological and economic impacts,affecting farm profitability and forest composition throughout the world.Bacterial vector-borne pathogens have evolved sophisticated strategies to interact with their hemipteran insect vectors and plant hosts.These pathogens reside in plant vascular tissue,and their study represents an excellent opportunity to uncover novel biological mechanisms regulating intracellular pathogenesis and to contribute to the control of some of the world's most invasive emerging diseases.In this perspective,we highlight recent advances and major unanswered questions in the realm of bacterial vector-borne disease,focusing on liberibacters,phytoplasmas,spiroplasmas,and Xylella fastidiosa.

The 'lifecycle' of human beinqs: a call to explore vector-borne diseases from an ecosystem perspective

Background:Dengue virus,an Aedes mosquito-borne flavivirus,is associated with close to 400 million reported infections per annum worldwide.Reduction of dengue virus transmission depends entirely on limiting Aedes breeding or preventing adult female contact with humans.Currently,the World Health Organization promotes the strategic approach of integrated vector management in order to optimise resources for mosquito control.Main text:Neglected tropical disease researchers focus on geographical zones where the incidence of clinical cases,and prevalence of vectors,are high.In combatting those infectious diseases such as dengue that affect mainly low-income populations in developing regions,a mosquito-centric approach is frequently adopted.This prioritises environmental factors that facilitate or impede the lifecycle progression of the vector.Climatic variables(such as rainfall and wind speed)that impact the vector's lifecycle either causally or by happenstance also affect the human host's lifecycle',but in very different ways.The socioeconomic impacts of the same variables that influence vector control impact host vulnerability but at different points in the human lifecycle to those of the vector.Here,we argue that the vulnerability of the vector and that of the host interact in complex and unpredictable ways that are characteristic of(complex and intransigent)'wicked problems'.Moreover,they are treated by public health programs in ways that may ignore this complexity.This opinion draws on recent evidence showing that the best climate predictors of the scale of dengue outbreaks in Bangladesh cannot be explained through a simple vector-tohost causal model.Conclusions:In mapping causal pathways for vector-borne diseases this article makes a case to elevate the lifecycle of the human host to a level closer in equivalence to that of the veaor.Here,we suggest value may be gained from transferring Rittel and Webber's concept of a wicked(social)problem to dengue,malaria and other mosquito-transmitted public health concerns.This would take a'problem definition,rather than a,solution-finding,approach,particularly when considering problems in which climate impacts simultaneously on human and vector vulnerability.

Host movement,transmission hot spots,and vector-borne disease dynamics on spatial networks

We examine how spatial heterogeneity combines with mobility network structure to influence vector-borne disease dynamics.Specifically,we consider a Ross-Macdonald-type disease model on n spatial locations that are coupled by host movement on a strongly connected,weighted,directed graph.We derive a closed form approximation to the domain reproduction number using a Laurent series expansion,and use this approximation to compute sensitivities of the basic reproduction number to model parameters.To illustrate how these results can be used to help inform mitigation strategies,as a case study we apply these results to malaria dynamics in Namibia,using published cell phone data and estimates for local disease transmission.Our analytical results are particularly useful for understanding drivers of transmission when mobility sinks and transmission hot spots do not coincide.

Establishing research priorities in prevention and control of vector-borne diseases in urban areas:a collaborative process

Background:In 2015,following a call for proposals from the Special Programme for Research and Training in Tropical Diseases(TDR),six scoping reviews on the prevention and control of vector-borne diseases in urban areas were conducted.Those reviews provided a clear picture of the available knowledge and highlighted knowledge gaps,as well as needs and opportunities for future research.Based on the research findings of the scoping reviews,a concept mapping exercise was undertaken to produce a list of priority research needs to be addressed.Methods:Members of the six research teams responsible for the“VEctor boRne DiseAses Scoping reviews”(VERDAS)consortium’s scoping reviews met for 2 days with decision-makers from Colombia,Brazil,Peru,Pan-American Health Organization,and World Health Organization.A total of 11 researchers and seven decision-makers(from ministries of health,city and regional vector control departments,and vector control programs)completed the concept mapping,answering the question:“In view of the knowledge synthesis and your own expertise,what do we still need to know about vector-borne diseases and other infectious diseases of poverty in urban areas?”Participants rated each statement on two scales from 1 to 5,one relative to‘priority’and the other to‘policy relevance’,and grouped statements into clusters based on their own individual criteria and expertise.Results:The final map consisted of 12 clusters.Participants considered those entitled“Equity”,“Technology”,and“Surveillance”to have the highest priority.The cluster considered the most important concerns equity issues,confirming that these issues are rarely addressed in research on vector-borne diseases.On the other hand,the“Population mobility”and“Collaboration”clusters were considered to be the lowest priority but remained identified by participants as research priorities.The average policy relevance scores for each of the 12 clusters were roughly the same as the priority scores for all clusters.Some issues were not addressed during the brain-storming.This is the case for governance and for access and quality of care.Conclusions:Based on this work,and adopting a participatory approach,the concept mapping exercise conducted collaboratively with researchers from these teams and high-level decision-makers identified research themes for which studies should be carried out as a priority.

On the Range of Action of Adult Culex pipiens s.l.

Mosquitoes are an interesting topic due to their medical importance, as they play an active role in the transmission of many pathogens and parasites, acting as vectors for various pathologies that are deadly to humans, such as dengue, yellow fever, chikungunya, West Nile virus, encephalitis and malaria, among many others that are less common. In terms of morbidity and mortality caused by vector-borne diseases, mosquitoes are the most dangerous animals for humanity and, although they also play a role in the ecosystem as a food source for other organisms, their importance for public health cannot be overlooked. As highly efficient vectors, they put more than three billion people at risk, mainly in tropical and subtropical regions as well as in Europe, since heat waves and flooding are becoming more frequent and severe, and summers are getting longer and warmer, accelerating mosquito development, biting rates, and the incubation of the pathogens within their bodies. Female mosquitoes bite to acquire proteins for the development of their ovaries and eggs and, in the process, acquire pathogens and/or parasites from one vertebrate host and transmit them to another, usually after a short period of replication. Three of their four life stages are lived in still freshwater, so it is crucial to understand their range of action when they reach adulthood and leave the water, in order to plan and implement local prevention measures. A set of georeferenced abundance data collected in mainland Portugal over seven years was linked to cartographed water bodies in a geographic information system to estimate the distances at which Culex pipiens s.l. had a significant presence, with criteria based on the size of the catches. The result allows for an estimate of the fly range of those mosquitoes, which can be used to focus countermeasures.

Asymptotic Analysis of a Stochastic Model of Mosquito-Borne Disease with the Use of Insecticides and Bet Nets

Ross’ epidemic model describing the transmission of malaria uses two classes of infection, one for humans and one for mosquitoes. This paper presents a stochastic extension of a deterministic vector-borne epidemic model based only on the class of human infectious. The consistency of the model is established by proving that the stochastic delay differential equation describing the model has a unique positive global solution. The extinction of the disease is studied through the analysis of the stability of the disease-free equilibrium state and the persistence of the model. Finally, we introduce some numerical simulations to illustrate the obtained results.