The impact of temperature and precipitation on blacklegged tick activity and Lyme disease incidence in endemic and emerging regions

Abstract

BackgroundThe incidence of Lyme disease shows high degrees of inter-annual variation in the northeastern United States, but the factors driving this variation are not well understood. Complicating matters, it is also possible that these driving factors may vary in regions with differing histories of Lyme disease endemism. We evaluated the effect of the number of hot (T > 25 °C), dry (precipitation = 0) days during the questing periods of the two immature Ixodes scapularis life stages (larval and nymphal) on inter-annual variation in Lyme disease incidence between 2000 and 2011 in long-term endemic versus recently endemic areas. We also evaluated the effect of summer weather on tick questing activity and the number of ticks found on small mammals between 1994 and 2012 on six sites in Millbrook, NY.ResultsThe number of hot, dry days during the larval period of the previous year did not affect the human incidence of Lyme disease or the density of questing nymphs the following season. However, dry summer weather during the nymphal questing period had a significant negative effect on the incidence of Lyme disease in the long-term endemic areas, and on the density of questing nymphs. Summer weather conditions had a more pronounced effect on actively questing I. scapularis collected via dragging than on the number of ticks found feeding on small mammals. In recently endemic areas Lyme disease incidence increased significantly over time, but no trend was detected between disease incidence and dry summer weather.ConclusionsRecently endemic regions showed an increase in Lyme disease incidence over time, while incidence in long-term endemic regions appears to have stabilized. Only within the stabilized areas were we able to detect reduced Lyme disease incidence in years with hot, dry summer weather. These patterns were reflected in our field data, which showed that questing activity of nymphal I. scapularis was reduced by hot, dry summer weather.

Borrelia burgdorferiInfection and Lyme Disease in North American Horses: A Consensus Statement

“…The seroprevalence of B. burgdorferi in dogs, horses and humans is increasing nationwide, as is the range of the Ixodid tick . Data strongly support the regional spread of Ixodes ticks, and animal and human exposure to B. burgdorferi in the Midwest, Pacific, and East Coasts of the United States.…”

“…The seroprevalence of B. burgdorferi in dogs, horses and humans is increasing nationwide, as is the range of the Ixodid tick. 30,[44][45][46][47][48][49] Data strongly support the regional spread of Ixodes ticks, and animal and human exposure to B. burgdorferi in the Midwest, Pacific, and East Coasts of the United States. A recent review of 6 different literature searches, documented an increased incidence and prevalence of Ixodes scapularis and I. pacificus in the United States within the last 20 years (Fig 1).…”

Tick‐borne disease risk in a forest food web

“…In addition, I. scapularis are sensitive to extremes in temperature and humidity during the 95% of their lives spent away from a host (Ogden et al 2005, 2013, Levi et al 2015, Ostfeld and Brunner 2015. Winter cold as well as spring and summer heat and dryness could reduce larval and nymphal survival, and snow cover is thought to increase survival through insulation (Hayes et al 2015, Ostfeld and Brunner 2015, Burtis et al 2016.…”

A framework for predicting the effects of climate change on the annual distribution of Lyme borreliosis incidences

“…Gray 2008;Gray et al 2009;Jaenson and Lindgren 2011;Zöldi et al 2013;Li et al 2016). The forecasted remarkable summer decrease of tick biting activity and Lyme incidence in the future underpins the findings of Burtis et al (2016) on I. scapularis activity. From the predicted changes in the annual distribution of relative Lyme incidence the absolute annual incidence cannot be estimated directly.…”