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Lyme Disease

EphNotes

What is Lyme disease?

Lyme disease is caused by bacteria that are spread by tiny infected ticks (in Massachusetts, by deer ticks). Both people and animals can be infected with Lyme disease.

Where is Lyme disease found?

Lyme disease is most commonly found along the East Coast, the upper Midwest and the valleys of the far West. In MA, deer ticks are found everywhere, but especially in coastal areas, the islands and the Connecticut River Valley. The disease is most likely to be spread between late May and early autumn, when ticks are most active.

How is Lyme disease spread?

Deer ticks cling to plants near the ground in brushy, wooded, or grassy places. The ticks, which cannot jump or fly, climb onto animals and people who brush against the plants. Very young ticks, called larvae, which are no bigger than the period at the end of a sentence, pick up the bacteria that cause Lyme disease by biting infected animals, such as field mice. Slightly older ticks, called nymphs, which are the size of a poppy seed, are the stage most likely to bite and infect humans. Adult deer ticks can also transmit the disease, but they are not as great a risk as nymphs because the adult are less likely to bite humans and they are easier to see and remove.

Ticks live for 2 years and can infect wild and domestic animals as well as people. Not all ticks carry Lyme disease, and even being bitten by a deer tick does not mean that you will always get the disease. The tick must usually be attached for at least 24 hours to pass on the bacteria, so removing the tick promptly will greatly decrease your chances of being infected.

What are the symptoms of Lyme disease?

Early Stage (days to weeks): An early symptom of Lyme disease is usually, but not always, a rash where the tick was attached. The rash appears from 3 days to a month after the bite. It often starts as a small red area then spreads, clearing up in the center so it looks like a donut. However, the rash may not always appear like this. Flu-like symptoms, such as fever, headache, stiff neck, sore and aching muscles and joints, fatigue and swollen glands, are also common in the early stages of Lyme disease.

These early symptoms often go away by themselves after a few weeks, but the person may remain infected. Without medical treatment, about half the infected people will get the rash again in other places on their bodies, and many will experience more serious problems. Early treatment with antibiotics clears up the rash within days and usually prevents later problems.

Later Stages (months to years): Three major organ systems — the joints, nervous system and heart — can be affected. People with Lyme disease can develop late-stage symptoms even if they never had the donut-shaped rash. About 60% of people with untreated Lyme disease get arthritis in their large joints, usually knees, elbows and wrists. The arthritis can move from joint to joint and become chronic. About 10 to 20% of people who don’t get treatment develop nervous system problems. The most common problems include meningitis (an inflammation of the membranes covering the brain and spinal cord), facial weakness (Bell’s palsy) or other problems with nerves of the head, and weakness or pain (or both) in the hands, arms, feet and/or legs. These symptoms can last for months, often shifting between mild and severe. The heart beat also can be affected in Lyme disease, with slowing down of the heart rate and fainting. The effect on the heart can be early or late.

How is Lyme disease diagnosed?

Lyme disease can be fairly easy to diagnose when someone gets the classic rash. It is much harder without the rash because its other symptoms resemble other diseases, like flu. To help diagnose these cases, doctors can have patients’ blood tested for antibodies to the Lyme disease bacteria.

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