Climate Fact: Lyme Disease and Spring Rains
Lyme disease, the most common vector-borne disease in the United States, is mainly confined to the habitat of the deer tick (the disease’s most common transmission source), which is concentrated in the Northeast. In the Northeast since the 1970′s, average spring rainfall has been increasing at a rate of about 0.5 inches per decade, and the number of Lyme disease occurrences in a particular year corresponds to the rainfall levels from two years earlier, particularly the spring rainfall levels. After an adult deer tick feeds on a host, it loses its ability to take up water and may die prematurely if its habitat remains unusually dry. Because a deer tick takes two years to develop from an egg into an adult, a lack of deer tick eggs being laid in a dry year would result in fewer adult deer ticks hatching two years later.
Season: Spring
Sources: McCabe, G.J., and J.E. Bunnell. “Precipitation and the occurrence of Lyme disease in the Northeastern United States.” Vector Borne Zoonotic 4 (2004): 143-8 and Steere, A.C., et al., “The emergence of Lyme disease.” Journal of Clinical Investigation 113 (2004): 1093-1101 and Subak, S. “Effects of climate on variability in Lyme disease incidence in Northeastern United States.” American Journal of Epidemiology 157 (2003): 531-538 and Orloski, K.A., et al. “Surveillance for Lyme disease – United States, 1992-1998.” Surveillance Summaries (MMWR) 49 (2000): 1-11 and U.S. National Oceanic and Atmospheric Administration (NOAA): Climate Prediction Center. 5 January 2005. 26 June 2008 http://www.cpc.ncep.noaa.gov/charts.shtml
