Deer season may not only reduce the deer population in a given area; it could cause Lyme disease rates to fall as well, a new study finds, thanks to a drop in the population of disease-carrying ticks using deer as hosts.
The latest research comes from Connecticut, one of 13 states where 95 percent of Lyme disease cases occur. Operating with the knowledge that white-tailed deer serve as the primary host for the adult blacklegged tick (Ixodes scapularis), the research team from the Entomological Society of America surveyed 90 to 98 percent of permanent residents in a Connecticut community. They asked about their exposure to tick-related diseases between 1995 and 2008.
“Reducing deer populations to levels that reduce the potential for ticks to successfully breed should be an important component of any long-term strategy seeking to reduce the risk of people contracting Lyme disease,” the researchers wrote in their report.
While Lyme disease is the most commonly reported vectorborne illness in the U.S. — meaning it spreads from one organism to another via a third — the Centers for Disease Control and Prevention notes the disease does not occur nationwide. Northeast and upper Midwest states are the most likely to see disease spread.
This spread diminishes, according to the ESA’s recent study, when the surrounding deer population dwindles. Reducing deer population to 5.1 deer per square kilometer resulted in a 76 percent reduction the number of ticks, a 70 percent reduction in the entomological risk index (a collective measure of vector proximity and threat), and an 80 percent reduction in the number of Lyme disease cases reported by residents.
Reducing deer populations is, of course, a matter of recreation — something the team appears to have little objection to. “Good hunter access to deer habitat and a wide variety of management tools (bait, unlimited tags, incentive programs) are important components of a successful deer reduction strategy,” they argue.
Without effective strategies, Lyme disease could continue to spread. The illness is treated with antibiotics, and patients tend to make full recoveries; however, the CDC concedes that 10 to 20 percent of people will experience persistent or recurring symptoms, which could qualify as post-Lyme disease treatment syndrome. When antibiotics don’t offer returns to full health, the National Institutes of Health shows, patients may be diagnosed with “chronic Lyme disease.“
For ESA researchers, empirical evidence paints a clear picture: Fewer deer mean fewer incidents of Lyme disease, which makes for a safer population (not to mention one with a thriving venison market.) “Our study demonstrated that deer populations can be manipulated to reduce human interactions with deer, infected nymphal ticks, and human risk of contracting Lyme disease.”
Source: Kilpatrick H, Labonte A, Stafford K. The Relationship Between Deer Density, Tick Abundance, and Human Cases of Lyme Disease in a Residential Community. Journal of Medical Entomology. 2014.