Bambi gone bad: Getting to the heart of Lyme disease

August 2, 2012

Mark L. Friedman, MD, FACEP, FACP

My family and I live in the hot zone. Just walking in our yard without protection can result in serious, even life-threatening, tick-borne diseases, including Lyme disease, erlichiosis, and babesiosis (similar to malaria "“ sometimes fatal). In March 2007, right after we moved here, my wife found a deer tick crawling inside her sweater. She had not even been out of the house. We think the dog brought it in.

I am not talking about the jungles of Africa or the Amazon, but suburban Fairfield County Connecticut.

Last year Lyme disease was diagnosed in every state except Alaska and Hawaii. Everywhere I go in the endemic zone (the most heavily-infested states of Connecticut, Delaware, Massachusetts, Pennsylvania, New York, New Jersey, Maryland, Rhode Island, Wisconsin, Minnesota), people either have had the disease or know someone who has.

Some of their stories of missed diagnoses and lives ruined are truly horrific. In 2011 alone, 30,000 cases were reported to the Centers for Disease Control. Since the CDC estimates that only about 10 percent of cases are reported, the actual numbers may be on the order of 300,000 annually. This represents a major public health problem and a failure of public health policy.

These diseases (the list continually expands) are almost completely preventable.

The key to the biological control is reduction of the deer tick population below the critical threshold level necessary to support disease transmission. In the same way that mosquito control reduces malaria, tick control reduces Lyme disease. The only scientifically demonstrated means of control is reduction of the deer herd to a level that interrupts the life cycle of the deer tick (ixodes Scapularis), which is the principal vector of these diseases.

Reducing deer densities below 10 to 12 per square mile substantially reduces tick numbers and human Lyme disease, according to Kirby C. Stafford III, vice director and chief entomologist of the Connecticut Agricultural Experiment Station and one of the foremost tick experts.

It did not occur to me why this was until I watched a deer being "dressed" by a hunter. The animal's hide was "alive" with ticks. Hundreds, perhaps even a thousand, living on a single deer. I was thunderstruck by a thought. "This is dating central for ticks. The ticks are mating on the deer." When I shared this astonishing revelation with another doctor I was told: "Of course. All the entomologists know this.

My point is, most doctors and the public in general do not know this. This is the "missing link" between an overabundance of deer and the incidence of Lyme and other tick-borne diseases.

I love to watch wildlife, including deer. But unfortunately, due to the serious diseases their presence now brings, they are more safely watched in wilderness preserves than suburban yards.

Originally published Aug 2, 2012 6:00:18 AM.