scholarly journals Mechanistic movement models reveal ecological drivers of tick-borne pathogen spread

2021 ◽  
Vol 18 (181) ◽  
pp. 20210134
Author(s):  
Olivia Tardy ◽  
Catherine Bouchard ◽  
Eric Chamberland ◽  
André Fortin ◽  
Patricia Lamirande ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Tick Population ◽  
Infection Prevalence ◽  
Spread Rate ◽  
Infected Tick ◽  
Tick Density ◽  
Heterogeneous Landscapes ◽  
Tick Infection ◽  
Tick Borne Disease ◽  
Host Movement

Identifying ecological drivers of tick-borne pathogen spread has great value for tick-borne disease management. However, theoretical investigations into the consequences of host movement behaviour on pathogen spread dynamics in heterogeneous landscapes remain limited because spatially explicit epidemiological models that incorporate more realistic mechanisms governing host movement are rare. We built a mechanistic movement model to investigate how the interplay between multiple ecological drivers affects the risk of tick-borne pathogen spread across heterogeneous landscapes. We used the model to generate simulations of tick dispersal by migratory birds and terrestrial hosts across theoretical landscapes varying in resource aggregation, and we performed a sensitivity analysis to explore the impacts of different parameters on the infected tick spread rate, tick infection prevalence and infected tick density. Our findings highlight the importance of host movement and tick population dynamics in explaining the infected tick spread rate into new regions. Tick infection prevalence and infected tick density were driven by predictors related to the infection process and tick population dynamics, respectively. Our results suggest that control strategies aiming to reduce tick burden on tick reproduction hosts and encounter rate between immature ticks and pathogen amplification hosts will be most effective at reducing tick-borne disease risk.

scholarly journals Amblyomma aureolatum Genetic Diversity and Population Dynamics Are Not Related to Spotted Fever Epidemiological Scenarios in Brazil

Pathogens ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1146
Author(s):  
Karla Bitencourth ◽  
Marinete Amorim ◽  
Stefan Vilges de Oliveira ◽  
Gilberto Salles Gazêta
Keyword(s):  
Genetic Diversity ◽  
Population Dynamics ◽  
Spotted Fever ◽  
Tick Population ◽  
Rickettsia Felis ◽  
Disease Epidemiology ◽  
Rickettsia Rickettsii ◽  
D Loop ◽  
Tick Borne Disease ◽  
Rickettsia Bellii

Regional differences in tick-borne disease epidemiology may be related to biological variations between vector populations. Amblyomma aureolatum (Ixodida: Ixodidae), a neotropical tick, is known from several regions in Brazil. However, only in the metropolitan area of São Paulo (SP) state are there studies that establish its role as a vector of a pathogenic rickettsia (Rickettsia rickettsii). The aim of the study was to analyze the genetic diversity, population dynamics, and rickettsia infection in A. aureolatum populations from different spotted fever scenarios in Brazil. Samples were subjected to DNA extraction, amplification and sequencing of 12S rDNA, cytochrome oxidase subunit II and D-loop mitochondrial markers for tick population analyses, and gltA, htrA, ompA, and ompB genes for rickettsia researches. Of the 7–17 tick haplotypes identified, 5–13 were exclusive to each population and 2–12 for each epidemiological scenario, as well as three haplotypes shared by all populations. Amblyomma aureolatum populations are expanding, and do not appear to be genetically structured vis-a-vis the different epidemiological scenarios studied. Rickettsia bellii (in SP) and Rickettsia felis (in Santa Catarina) were identified as infecting A. aureolatum. No relationship between tick haplotypes and rickettsia types were observed.

scholarly journals Impact of the experimental removal of lizards on Lyme disease risk

2011 ◽  
Vol 278 (1720) ◽  
pp. 2970-2978 ◽  
Author(s):  
Andrea Swei ◽  
Richard S. Ostfeld ◽  
Robert S. Lane ◽  
Cheryl J. Briggs
Keyword(s):  
Lyme Disease ◽  
Disease Ecology ◽  
Disease Risk ◽  
Large Fraction ◽  
Host Community ◽  
Deer Mice ◽  
Infection Prevalence ◽  
Alternate Host ◽  
Experimental Removal ◽  
Tick Infection

The distribution of vector meals in the host community is an important element of understanding and predicting vector-borne disease risk. Lizards (such as the western fence lizard; Sceloporus occidentalis ) play a unique role in Lyme disease ecology in the far-western United States. Lizards rather than mammals serve as the blood meal hosts for a large fraction of larval and nymphal western black-legged ticks ( Ixodes pacificus —the vector for Lyme disease in that region) but are not competent reservoirs for the pathogen, Borrelia burgdorferi . Prior studies have suggested that the net effect of lizards is to reduce risk of human exposure to Lyme disease, a hypothesis that we tested experimentally. Following experimental removal of lizards, we documented incomplete host switching by larval ticks (5.19%) from lizards to other hosts. Larval tick burdens increased on woodrats, a competent reservoir, but not on deer mice, a less competent pathogen reservoir. However, most larvae failed to find an alternate host. This resulted in significantly lower densities of nymphal ticks the following year. Unexpectedly, the removal of reservoir-incompetent lizards did not cause an increase in nymphal tick infection prevalence. The net result of lizard removal was a decrease in the density of infected nymphal ticks, and therefore a decreased risk to humans of Lyme disease. Our results indicate that an incompetent reservoir for a pathogen may, in fact, increase disease risk through the maintenance of higher vector density and therefore, higher density of infected vectors.

Climate change and tick-borne encephalitis in the Greater Alpine region.

2021 ◽  
pp. 354-359
Author(s):  
Franz Rubel
Keyword(s):  
Climate Change ◽  
Far East ◽  
Climate Change Impacts ◽  
Alpine Region ◽  
European Alps ◽  
Far East Of Russia ◽  
The Caucasus ◽  
Tick Density ◽  
Tick Borne Encephalitis ◽  
Tick Borne Disease

Abstract Tick-borne encephalitis (TBE) is a viral tick-borne disease. The distribution of human TBE cases ranges from the French departments bordering Germany through Central and Eastern Europe, the Caucasus and Kazakhstan to the Far East of Russia and China. In this expert opinion, TBE is described in the greater area of the European Alps, denoted as the Greater Alpine Region (GAR). It also includes reported tick-borne encephalitis cases and evidence for climate change impacts on tick density and distribution as well as the prevalence and intensity of TBE.

Trends and oscillations in tick population dynamics

1995 ◽  
Vol 175 (4) ◽  
pp. 511-516 ◽  
Author(s):  
Tamara E. Awerbuch ◽  
Sonja Sandberg
Keyword(s):  
Population Dynamics ◽  
Tick Population

Eradication and control of livestock ticks: biological, economic and social perspectives

Parasitology ◽  
2011 ◽  
Vol 138 (8) ◽  
pp. 945-959 ◽  
Author(s):  
ALAN R. WALKER
Keyword(s):  
Land Use ◽  
Population Dynamics ◽  
Tick Population ◽  
Control Methods ◽  
Social Perspectives ◽  
Density Dependent Mortality ◽  
Livestock Breeding ◽  
The Social ◽  
And Control ◽  
Dependent Mortality

SUMMARYComparisons of successful and failed attempts to eradicate livestock ticks reveal that the social context of farming and management of the campaigns have greater influence than techniques of treatment. The biology of ticks is considered principally where it has contributed to control of ticks as practiced on farms. The timing of treatments by life cycle and season can be exploited to reduce numbers of treatments per year. Pastures can be managed to starve and desiccate vulnerable larvae questing on vegetation. Immunity to ticks acquired by hosts can be enhanced by livestock breeding. The aggregated distribution of ticks on hosts with poor immunity can be used to select animals for removal from the herd. Models of tick population dynamics required for predicting outcomes of control methods need better understanding of drivers of distribution, aggregation, stability, and density-dependent mortality. Changing social circumstances, especially of land-use, has an influence on exposure to tick-borne pathogens that can be exploited for disease control.

Effect of host populations on the intensity of ticks and the prevalence of tick-borne pathogens: how to interpret the results of deer exclosure experiments

Parasitology ◽  
2008 ◽  
Vol 135 (13) ◽  
pp. 1531-1544 ◽  
Author(s):  
A. PUGLIESE ◽  
R. ROSÀ
Keyword(s):  
Ixodes Ricinus ◽  
Dynamic Models ◽  
Infection Risk ◽  
Northern Italy ◽  
Pathogen Transmission ◽  
Infection Prevalence ◽  
Tick Density ◽  
Dead End ◽  
Tick Borne Encephalitis ◽  
Experimental Plots

SUMMARYDeer are important blood hosts for feeding Ixodes ricinus ticks but they do not support transmission of many tick-borne pathogens, so acting as dead-end transmission hosts. Mathematical models show their role as tick amplifiers, but also suggest that they dilute pathogen transmission, thus reducing infection prevalence. Empirical evidence for this is conflicting: experimental plots with deer removal (i.e. deer exclosures) show that the effect depends on the size of the exclosure. Here we present simulations of dynamic models that take into account different tick stages, and several host species (e.g. rodents) that may move to and from deer exclosures; models were calibrated with respect to Ixodes ricinus ticks and tick-borne encephalitis (TBE) in Trentino (northern Italy). Results show that in small exclosures, the density of rodent-feeding ticks may be higher inside than outside, whereas in large exclosures, a reduction of such tick density may be reached. Similarly, TBE prevalence in rodents decreases in large exclosures and may be slightly higher in small exclosures than outside them. The density of infected questing nymphs inside small exclosures can be much higher, in our numerical example almost twice as large as that outside, leading to potential TBE infection risk hotspots.

scholarly journals Delay-dependent attractivity on a tick population dynamics model incorporating two distinctive time-varying delays

2021 ◽  
Vol 477 (2251) ◽  
pp. 20210302
Author(s):  
Chuangxia Huang ◽  
Jian Zhang ◽  
Jinde Cao
Keyword(s):  
Population Dynamics ◽  
Global Attractivity ◽  
Positive Equilibrium ◽  
Tick Population ◽  
Time Varying ◽  
Dynamics Model ◽  
Population Dynamics Model ◽  
All Solutions ◽  
Positive Equilibrium Point ◽  
Delay Dependent

In this paper, we aim to investigate the influence of delay on the global attractivity of a tick population dynamics model incorporating two distinctive time-varying delays. By exploiting some differential inequality techniques and with the aid of the fluctuation lemma, we first prove the persistence and positiveness for all solutions of the addressed equation. Consequently, a delay-dependent criterion is derived to assure the global attractivity of the positive equilibrium point. And lastly, some numerical simulations are presented to verify that the obtained results improve and complement some existing ones.

First Records of Hyalomma aegyptium (Acari: Ixodida: Ixodidae) from the Russian Spur-Thighed Tortoise, Testudo graeca nikolskii, with an Analysis of Tick Population Dynamics

1998 ◽  
Vol 84 (6) ◽  
pp. 1303 ◽  
Author(s):  
Richard G. Robbins ◽  
William B. Karesh ◽  
Paul P. Calle ◽  
Olga A. Leontyeva ◽  
Solomon L. Pereshkolnik ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Tick Population ◽  
Testudo Graeca
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