CR 27:177-187 (2004)  -  doi:10.3354/cr027177

ABSTRACT: This study demonstrates that climatic variables in April, May, and June have strong relationships with Lyme disease rates in the USA during the peak summer season. The disease system appears to be constrained more by moisture than temperature. A predictive ‘climatic envelope’ model is developed based on mean air temperatures, total precipitation, and total soil moisture surplus values for the months of April, May, and June. The middle 90% of cases with greater than 10 reports per 100000 people for the 1994 to 1999 reporting period occurred in counties with an average temperature in April, May, and June between 10.8 and 19.4°C, total soil moisture surplus values of 1.3 to 13.2 cm, and total precipitation values of 19.7 to 37.8 cm. This simple model is used to produce a risk map for Lyme disease that identifies the peak incidence regions in the Northeast and upper Midwest as well as regions that are in the suitable climate range for the disease to be endemic but in which the disease is currently rare or non-existent.

KEY WORDS: Climate · Geography · Lyme disease · Seasonality · Climate envelope model