Lyme disease has been linked to the deaths of three people who suffered sudden cardiac death.
In their weekly Morbidity and Mortality report, the U.S. Centers for Disease Control said that health officials had found signs of Lyme disease in three people who died of sudden cardiac death, although none had been diagnosed with Lyme disease at the time of their deaths.
The two men and a woman were between the ages of 26 and 38 years old.
Although the disease has been known to cause cardiac problems before, it has only been linked to four other sudden cardiac deaths since the discovery of the bacterial infection in 1975.
In August the CDC estimated that the tick-born infection actually affects 10 times as many people as previously thought, approximately 300,000 per year.
The last three cases took place over the last 13 months. Two of the people who died had underlying heart conditions. One person had high blood pressure and coronary artery disease; the other had a disease that predisposed the person to having a fast heart rhythm.
Dr. William Schaffner, said the bacteria that causes Lyme disease is often not localized in the body. "The bacteria in Lyme disease can circulate throughout the body and it mostly causes problem with joints," he said. "Occasionally when they get to an organ such as the heart," it can become inflamed.
If the heart becomes inflamed, it's possible that the normal heart beat rhythm can become disrupted, said Schaffner, which can lead to an irregular heartbeat that can sometimes be followed by sudden cardiac death.
"This is very, very unusual," said Schaffner. "It's noteworthy that two of these people had underlying heart disease."
Dr. Joseph Forrester, an epidemic intelligence service officer with the Bacterial Diseases Branch for the Division of Vector-Borne Diseases at CDC, said health officials plan to study data to see how often Lyme disease leads to a patient's heart becoming inflamed, also called Lyme carditis.
"We're ... going through all available surveillance data we have from the federal and state and local level and trying to figure which group is most at risk for developing Lyme carditis and who is at risk for dying," said Forrester.
Forrester also emphasized how rarely Lyme disease-related cardiac deaths occur. Two of the patients in the report were first found to have Lyme disease after samples of their hearts were sent to a tissue bank. The tissue bank then reviewed its records for any other cases in which sudden death could have been related to Lyme disease. Of the bank's 20,000 samples dating back to 2004, only the original two samples were positive for Lyme disease.
"One thing we don't want to do is have people get worried unnecessarily," said Forrester. "We want to raise the opportunity to impart upon the public that the best way to prevent against getting Lyme carditis is to prevent getting Lyme disease in the first place.
Forrester said people should remain vigilant when going outdoors, use tick-repellant and do regular tick checks.