The National Academies: What You Need To Know About Infectious Disease

The National Academies

What You Need To Know About Infectious Disease

Lyme Disease

Lyme disease is an inflammatory disease caused by the bacterium Borrelia burgdorferi, which normally lives in mice, squirrels, and other small animals. It is transmitted among these animals—and to humans—through the bites of certain species of ticks.

Lyme disease was first reported in the United States in the town of Old Lyme, Connecticut, in 1975. Cases have now been reported in most parts of the United States. Most of the cases occur in the Northeast, some parts of Minnesota and Wisconsin, the Mid-Atlantic states, and along the Pacific coast. Lyme disease is usually seen during the late spring, summer, and early fall.

The first symptom to appear is a circular rash around the site of the bite from a tick that may look like a “bull’s eye.” A distinctive feature of the rash is that it gradually expands over a period of several days, reaching up to 12 inches across. Some individuals may also experience symptoms of fatigue, chills, fever, headache, muscle and joint aches, and swollen lymph nodes. In some cases, these may be the only symptoms of infection.

If left untreated, the infection may spread to other parts of the body within a few days to weeks, producing an array of discrete symptoms. These include loss of muscle tone on one or both sides of the face (called facial or Bell’s palsy), severe headaches and neck stiffness due to meningitis, shooting pains that may interfere with sleep, heart palpitations and dizziness due to changes in heartbeat, and pain that moves from joint to joint. Many of these symptoms will resolve, even without treatment.

Not everyone that is bitten by a tick will become infected with Lyme disease. However, if the illness is identified during the early stages of the infection, individuals treated with antibiotics usually recover rapidly and completely. Anti-inflammatory medications, such as ibuprofen, are sometimes prescribed to relieve joint stiffness.

In rare cases, a person will continue having symptoms that can interfere with daily life. Some people call this post-Lyme disease syndrome. At this time, there is no effective treatment for this syndrome.

Reducing exposure to ticks is the best way to prevent Lyme disease infections. This can be done by wearing long-sleeved pants and shirts and high boots when outside. Using insect repellant on all exposed skin and clothing can also help reduce exposure. Because the ticks that can carry Lyme disease are so tiny, it is important to remove all clothes and inspect all skin surfaces after returning home from a place where ticks are prevalent. Wearing light-colored clothes can make it easier to spot ticks.


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What do you know about infectious disease?

True or False: Our bodies contain at least 10 times more human cells than bacterial cells.

  • Sorry, that’s incorrect.

    Our bodies contain at least 10 times more bacterial cells than human cells. 

  • Correct!

    Our bodies contain at least 10 times more bacterial cells than human cells. 

Infectious Disease Defined


The main trunk of the network of tubes that carries air to and from the lungs, sometimes referred to as the “windpipe.”

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