US Lyme Disease Cases 10 Times Greater than Reported, CDC Suggests

New figures released Monday by the Centers for Disease Control and Prevention (CDC) suggest that there are 300,000 annual cases of Lyme disease in the US -- about 10 times higher than the number of cases officially reported by doctors each year.

The CDC's estimates come from three ongoing Lyme disease studies. The first study is analyzing the medical claims information of 22 million people across a six year period; the second is based on a survey of clinical laboratories and the third project analyzes self-reported instances of Lyme disease from the general public. The results of the ongoing studies will be published by the CDC upon their completion. The organization released partial results of the study Monday to coincide with the 2013 International Conference on Lyme Borreliosis and other Tick-borne Diseases in Boston.

Lyme disease is the most commonly reported tick-borne illness. Every year about 30,000 cases of Lyme disease are reported, a figure the CDC contends is about 10 times less than the actual number of cases in a given year. The finding is consistent with previous studies conducted in the 1990s which suggested that the true number of cases is three to 12 times higher than the number of reported cases.

"We know that routine surveillance only gives us part of the picture, and that the true number of illnesses is much greater," Paul Mead, chief of epidemiology and surveillance for CDC's Lyme disease program, said in a statement. "This new preliminary estimate confirms that Lyme disease is a tremendous public health problem in the United States, and clearly highlights the urgent need for prevention."

Lyle R. Petersen, director of CDC's Division of Vector-Borne Diseases, said: "We need to move to a broader approach to tick reduction, involving entire communities, to combat this public health problem."

Most cases of Lyme disease reported in the US occur in the Northeast and the Midwest, with 96 percent of the cases occurring in 13 states: Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Vermont, Virginia and Wisconsin.

Black-legged ticks infected with the bacterium Borrelia burgdorferi spread Lyme disease to humans. Typical symptoms include fever, headache, fatigue and a distinct skin rash that looks like a bull's-eye around the tick bite. If left untreated, the disease can spread into joints and the nervous and cardiovascular systems.

The CDC suggests people prevent Lyme disease by wearing tick repellent when outdoors, checking for ticks on your person daily, showering soon after being outdoors and calling your doctor immediately if you develop a fever or rash after being bitten by a tick.