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Excess deer spread Lyme: An Inconvenient Truth

Early summer in Connecticut holds the highest risk for exposure to Lyme disease. The tiny nymph deer ticks are actively feeding and almost invisible. Another risk factor is that in the warm weather more time is spent outdoors with less protective clothing.  The previous approach to avoiding Lyme disease by protecting oneself needs to be expanded to options that look to control the tick population as a whole. 

Within 5 to 10 years most Connecticut residents or visitors will encounter deer ticks and Lyme disease either by discovering an embedded tick, finding the typical diagnostic bull’s eye rash or developing fever and aches. Surveys show that as many as 45% of households within Fairfield County have a member affected by Lyme in the previous year.

According to the Centers for Disease Control and Prevention (CDC), the annually reported number of adults and children diagnosed with Lyme disease has increased 25 fold over the last 20 years and by 29% in Fairfield County in just the last year. Numbers of the newer tick related infections such as Ehrlichiosis are also growing at an alarming rate as the number of ticks infected with these diseases goes up.

But Lyme disease has not always been with us. It was first recognized in a group of school-age arthritis patients from the area of Lyme, CT in 1975. And numbers have increased rapidly since then. According to the Connecticut Department of Public Health, Connecticut has had the highest rate of Lyme disease in the United States since 1992.  The highest numbers of new cases are in Fairfield County.  The ever increasing Lyme disease has been attributed to many factors including increasing tick populations, increasing deer populations, and increased residential development creating ideal deer habitat on woodland edges.  

How can this situation be reversed? Dr Kirby Stafford PhD., a national expert on ticks with the CT Agriculture Experiment Station  (caes), says “Until we can get our deer numbers under control, ticks will continue to thrive.” Many people are confused by the role of other animals such as white footed mice in the tick’s life cycle, but the only animal that the tick is truly dependant on is the deer, which the tick needs in order to reproduce. This is fortunate for us-we can put science to work here and effectively eradicate Lyme disease: if the numbers of this one species, deer, are reduced below the threshold for successful tick reproduction, tick populations crash and become all but extinct (Kirby Stafford 2006).

The Connecticut Department of Public Health’s response to the growing Lyme epidemic has so far focused on partially protective personal measures to avoid the deer ticks that transmit the disease to humans. These include thorough daily body checks for ticks, protective clothing, tick repellants and landscape modifications such as creating a woodchip or gravel barrier around yards. However, these measures that are intended to help only the most vigilant individuals have failed to curb the continued increase in the rate of Lyme disease.  According to the CDC, Lyme rates have increased by 29% in just the last year in Fairfield County. 

A more effective approach, and one that would benefit all residents as well as future generations, would be one that treats the cause of the problem, the excess deer numbers, says Dr Sam Telford, an expert with 20 years of experience at the Harvard School of Public Health. 

Recent research on how low deer numbers need to be reduced, performed here in Connecticut by Dr Stafford has shown dramatic reductions in tick populations when deer were reduced to 10.5 per square mile.  This happens also to be a healthy balanced number of deer for the forests and woodlands of our region to support. 

How can deer numbers be reduced?
In the last 3 years 15 local Fairfield County towns have acknowledged the multiple problems caused by excess deer numbers and have joined a county-wide alliance called the Fairfield County Municipal Deer Management Alliance. In July the efforts of the Alliance were taken to the statewide level as the group agreed to participate in the new Connecticut Coalition to Eradicate Lyme Disease. This new coalition is already discovering similar efforts in neighboring states to get deer numbers back in balance. Many Alliance member towns have already instituted deer reduction programs through planned, controlled hunting. Sport hunting alone has been found to be inadequate in Fairfield County due to the short hunting season, the limited land access given to hunters and the dwindling number of hunters. Hunting may have to become less a recreation and more a community service or civic duty when the impacts of deer are broadly recognized (Riley, Ecoscience, 2003). There is still a reluctance of some residents to accept the need or understand the benefits of deer and tick reduction. A statewide public information campaign could really make a difference.