Effect of Rising Temperature on Lyme Disease:Ixodes scapularisPopulation Dynamics andBorrelia burgdorferiTransmission and Prevalence

Abstract

Warmer temperatures are expected to increase the incidence of Lyme disease through enhanced tick maturation rates and a longer season of transmission. In addition, there could be an increased risk of disease export because of infected mobile hosts, usually birds. A temperature-driven seasonal model of Borrelia burgdorferi (Lyme disease) transmission among four host types is constructed as a system of nonlinear ordinary differential equations. The model is developed and parametrized based on a collection of lab and field studies. The model is shown to produce biologically reasonable results for both the tick vector (Ixodes scapularis) and the hosts when compared to a different set of studies. The model is used to predict the response of Lyme disease risk to a mean annual temperature increase, based on current temperature cycles in Hanover, NH. Many of the risk measures suggested by the literature are shown to change with increased mean annual temperature. The most straightforward measure of disease risk is the abundance of infected questing ticks, averaged over a year. Compared to this measure, which is difficult and resource-intensive to track in the field, all other risk measures considered underestimate the rise of risk with rise in mean annual temperature. The measure coming closest was “degree days above zero.” Disease prevalence in ticks and hosts showed less increase with rising temperature. Single field measurements at the height of transmission season did not show much change at all with rising temperature.

Modeling of Control Efforts against Rhipicephalus sanguineus, the Vector of Rocky Mountain Spotted Fever in Sonora Mexico

“…The process based model used to investigate multiple intervention strategies is based on a prior model of the tick vector for Lyme Disease, Ixodes scapularis [ 24 , 25 , 26 ]. Dynamic compartments for maturing, questing, and feeding larvae, nymphs and adults were included for both infected and uninfected populations, as well as population dynamics of host species, represented as a system of ordinary differential equations.…”

“…Other population parameters were drawn as necessary from the study by Ioffe-Uspensky et al (1997), with the exit rate of ticks from the feeding compartments based on stage-dependent feeding times, as well as average clutch size and exit rate of the pre-oviposition period, which was corroborated by a second study [ 18 , 36 ]. Egg hatching rates are known to be temperature dependent, however not enough data was found to give a response curve [ 37 ], so the rate was borrowed from a prior modeling study [ 24 ]. Median time of larval hardening was taken from Koch and Tuck, and interpreted as a half-life [ 20 ].…”

“…The model developed in this study is based on prior models of Ixodes scapularis and revised to include temperature and humidity responses, and other development parameters particular to R. sanguineus , and include the appropriate host structure [ 24 , 25 , 26 ]. Ixodes sp.…”

Estimating disease vector population size from citizen science data

“…The mean annual temperature was identified as a potential predictor of human outdoor activity which could correlate with exposure to ticks [ 38 , 41 ]. It is important to note that temperature also impacts tick densities and activity and is unlikely to explain much of the variability in human outdoor activity behaviour [ 42 ]. The mean annual temperature for each county was obtained from the US Climate Divisional Database through the National Oceanic and Atmospheric Administration (NOAA) [ 43 ].…”

Effects of rising temperature and prescribed fire on Amblyomma Americanum with ehrlichiosis

“…al. [26] conducted a modeling study that evaluated the effect of rising temperatures on these ticks and the primary disease that they transmit, Lyme disease. They found that rising temperature has the potential to increase transmission risk to humans due to higher tick numbers and a longer season of transmission.…”