Lyme Disease Modeling and Risk Factors: Comparing microclimate measurements to New York State Mesonet observations

Abstract:

Lyme disease (LD) is caused by the bacteria Borrelia burgdorferi, which is transmitted through the bite of the blacklegged tick (Ixodes scapularis). It is the most common vector-borne disease in the United States, with approximately 30,000 reported cases annually. Recent studies indicate a possible ten-fold underestimate of actual LD cases, potentially impacting 300,000 people each year. Humans are at risk for acquiring LD anywhere I. scapularis ticks are found, particularly in forests with dense leaf litter and along trail or forest edges where ticks frequently quest in search of a bloodmeal. We reviewed the existing literature on I. scapularis and found evidence for a strong correlation between temperature, humidity and tick questing behavior. However, studies examining the relationship between tick behavior, microclimate and weather station data are rare. Our aim was to determine if local on-site temperature and humidity measurements can be accurately estimated from data collected by the New York State Mesonet and related to local tick activity. Our research looks to use Mesonet weather information to accurately predict the risk of encountering ticks locally.

We measured temperature, relative humidity, and dewpoint at heights of 0.2 m, 1 m, and 2 m using HOBO data loggers during summer 2020 from early June to late July. Measurements were taken at four sites in Upstate New York, each paired with a nearby Mesonet weather station. We had three sets of equipment, so the loggers were rotated around the four sites with a regular and consistent rotation. The heights were chosen to see how temperature and humidity vary with height and are relevant to tick habitat use. We sampled I. scapularis using a 1-m square drag cloth at each station at least two times following standardized New York State Department of Health (NYSDOH) sampling protocols. We also compared field measurements of temperature and humidity taken by NYSDOH prior to tick sampling with the station readings from the nearby Mesonet stations. We examined the relationship between tick density, sample time, and temperature and relative humidity.

Future directions for this project include looking at park visitation rates to determine which parks have the greatest risk of tick encounters taking into account visitation rates, temperature, humidity, and precipitation.