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Maintaining pathogens with short infectivity in seasonally structured tick populations: relative importance of three transmission pathways

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Please use this identifier to cite or link to this item: http://hdl.handle.net/1928/10415

Maintaining pathogens with short infectivity in seasonally structured tick populations: relative importance of three transmission pathways

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Title: Maintaining pathogens with short infectivity in seasonally structured tick populations: relative importance of three transmission pathways
Author: Nonaka, Etsuko
Advisor(s): Wearing, Helen
Steinberg, Stanly
Committee Member(s): Pedro, Embid
Department: Mathematics and Statistics
Subject: epidemiology
stage-structured population model
tick-borne encephalitis
seasonality
LC Subject(s): Tick-borne diseases in animals--Transmission--Mathematical models.
Tick-borne encephalitis--Transmission--mathematical models.
Encephalitis--Seasonal variations--Mathematical models.
Degree Level: Masters
Abstract: Infectivity periods of different tick-borne pathogens in host species can vary widely, and the variation affects how the pathogens are maintained in tick populations. In addition to systemic and vertical transmission, cofeeding transmission has been proposed as an important route for the persistence of pathogens with short infectivity (e.g., tick-borne encephalitis causing viruses, TBEv). Because cofeeding transmission requires ticks to feed simultaneously, the temporal dynamics of tick populations become important. Existing models of tick-borne diseases do not fully incorporate all three transmission pathways (systemic, vertical, and cofeeding transmission) and tick seasonality. We developed a comprehensive stage-structured population model that includes seasonality and evaluated the relative importance of the three transmission pathways for pathogens with short infectivity. We used the next generation matrix method to calculate R0 and performed elasticity analyses for complex disease systems. We found that cofeeding transmission is a critically important route for such pathogens to persist in seasonal tick populations over the reasonable range of parameter values. At higher but still plausible rates of vertical transmission, our model suggests that vertical transmission can be a strong enhancer of pathogen prevalence when it operates in combination with cofeeding transmission. We discuss potential mechanisms behind consistent but low prevalence of TBEv observed in tick populations in the field.
Graduation Date: July 2009
URI: http://hdl.handle.net/1928/10415


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