We explored a compartment“susceptible-infected-recovered”model to prioritize and test the effectiveness of dog-and tick-based interventions against Rocky Mountain spotted fever and its tick vector Rhipicephalus sang...We explored a compartment“susceptible-infected-recovered”model to prioritize and test the effectiveness of dog-and tick-based interventions against Rocky Mountain spotted fever and its tick vector Rhipicephalus sanguineus s.l.In the face of increasingly urban epidemics of RMSF with high case fatality,particularly targeting marginalized communities,wrap-around campaigns(comprising all or some of canine culling,fertility control,and restraint to property;on-dog and environmental acaricide;and education and awareness programs for public health workers and at-risk residents)are unsustainably resource-intensive and may lack efficacy in managing the very hard to control tick.Our model allows us to strategize interventions and develop an optimized campaign against RMSF,using parameters associated with the epidemic in Ensenada,Baja California as an example.Combining usage of acaricides on dogs and the environment optimized success as measured by up to 10 years of no new canine cases,a proxy for human cases,as well as reduced tick burden.Success was greater when the campaign was begun in winter or spring and achieved at least 60%coverage.This combination was considerably more successful than either dog or environmental acaricide alone,culling of dogs which was only successful with 100%of dogs removed,and spay/neuter campaigns which did not reduce tick burdens.However,spay/neuter of outside dogs as an adjunct to the acaricide campaign helped stabilize the canine population and encouraged herd immunity.Although parameterized for Ensenada,the model can easily be run for other communities where data on canine tick burden and tick life history traits are available,in order to tailor intervention details such as optimal timing,coverage,and re-application frequency even when public health resources are limited.展开更多
Rocky Mountain spotted fever(RMSF)is a fatal tick-borne zoonotic disease that has emerged as an epidemic in western North America since the turn of the 21st century.Along the US south-western border and across norther...Rocky Mountain spotted fever(RMSF)is a fatal tick-borne zoonotic disease that has emerged as an epidemic in western North America since the turn of the 21st century.Along the US south-western border and across northern Mexico,the brown dog tick,Rhipicephalus sanguineus,is responsible for spreading the disease between dogs and humans.The widespread nature of the disease and the ongoing epidemics contrast with historically sporadic patterns of the disease.Because dogs are amplifying hosts for the Rickettsia rickettsii bacteria,transmission dynamics between dogs and ticks are critical for understanding the epidemic.In this paper,we developed a compartment metapopulation model and used it to explore the dynamics and drivers of RMSF in dogs and brown dog ticks in a theoretical region in western North America.We discovered that there is an extended lag—as much as two years—between introduction of the pathogen to a naïve population and epidemic-level transmission,suggesting that infected ticks could disseminate extensively before disease is detected.A single large city-size population of dogs was sufficient to maintain the disease over a decade and serve as a source for disease in surrounding smaller towns.This model is a novel tool that can be used to identify high risk areas and key intervention points for epidemic RMSF spread by brown dog ticks.展开更多
基金funded by the School of Veterinary Medicine University of California,Davis and the Pacific Southwest Regional Center of Excellence for Vector-Borne Diseases by the CDC(Cooperative Agreement 1U01CK000649).
文摘We explored a compartment“susceptible-infected-recovered”model to prioritize and test the effectiveness of dog-and tick-based interventions against Rocky Mountain spotted fever and its tick vector Rhipicephalus sanguineus s.l.In the face of increasingly urban epidemics of RMSF with high case fatality,particularly targeting marginalized communities,wrap-around campaigns(comprising all or some of canine culling,fertility control,and restraint to property;on-dog and environmental acaricide;and education and awareness programs for public health workers and at-risk residents)are unsustainably resource-intensive and may lack efficacy in managing the very hard to control tick.Our model allows us to strategize interventions and develop an optimized campaign against RMSF,using parameters associated with the epidemic in Ensenada,Baja California as an example.Combining usage of acaricides on dogs and the environment optimized success as measured by up to 10 years of no new canine cases,a proxy for human cases,as well as reduced tick burden.Success was greater when the campaign was begun in winter or spring and achieved at least 60%coverage.This combination was considerably more successful than either dog or environmental acaricide alone,culling of dogs which was only successful with 100%of dogs removed,and spay/neuter campaigns which did not reduce tick burdens.However,spay/neuter of outside dogs as an adjunct to the acaricide campaign helped stabilize the canine population and encouraged herd immunity.Although parameterized for Ensenada,the model can easily be run for other communities where data on canine tick burden and tick life history traits are available,in order to tailor intervention details such as optimal timing,coverage,and re-application frequency even when public health resources are limited.
基金This project was funded by the Pacific Southwest Regional Center of Excellence for Vector-borne Diseases funded by the US Centers for Disease Control and Prevention(Cooperative Agreement 1U01CK000649).
文摘Rocky Mountain spotted fever(RMSF)is a fatal tick-borne zoonotic disease that has emerged as an epidemic in western North America since the turn of the 21st century.Along the US south-western border and across northern Mexico,the brown dog tick,Rhipicephalus sanguineus,is responsible for spreading the disease between dogs and humans.The widespread nature of the disease and the ongoing epidemics contrast with historically sporadic patterns of the disease.Because dogs are amplifying hosts for the Rickettsia rickettsii bacteria,transmission dynamics between dogs and ticks are critical for understanding the epidemic.In this paper,we developed a compartment metapopulation model and used it to explore the dynamics and drivers of RMSF in dogs and brown dog ticks in a theoretical region in western North America.We discovered that there is an extended lag—as much as two years—between introduction of the pathogen to a naïve population and epidemic-level transmission,suggesting that infected ticks could disseminate extensively before disease is detected.A single large city-size population of dogs was sufficient to maintain the disease over a decade and serve as a source for disease in surrounding smaller towns.This model is a novel tool that can be used to identify high risk areas and key intervention points for epidemic RMSF spread by brown dog ticks.
