Lyme Disease

Lyme Disease

Blood-sucking deer ticks can transmit Lyme disease to humans, which can lead to headaches, fever, rashes, and even neurological problems.


5 - 8


Biology, Health


tick lyme

Lyme disease is an infectious bacterial infection that is spread by ticks, characterized by a distinctive, expanding 'bullseye' redness and swelling around the site of the tick bite.

Photograph by Centers for Disease Control and Prevention
Lyme disease is an infectious bacterial infection that is spread by ticks, characterized by a distinctive, expanding 'bullseye' redness and swelling around the site of the tick bite.

After playing outside in tall grass, be sure to check for ticks. Ticks are small arachnids that consume the blood of animals and humans, and if a tick has been infected by bacteria, it can transmit the infection to humans. One of the diseases that humans can contract from ticks, typically deer ticks (also known as black-legged ticks), is called Lyme disease. Lyme disease is caused by a bacterium known as Borrelia burgdorferi. The Centers for Disease Control and Prevention (CDC) estimates that about three hundred thousand people suffer from this disease every year.

Generally, in the spring and early summer, when temperatures start to grow warmer, ticks begin to seek a host. Near winter, when temperatures drop to below 8.9°C (45°F), ticks become dormant. When a tick attaches to a host, there are a few things to keep in mind.

The sooner the tick is removed from the skin, the better, as it has less time to transmit Lyme disease to the host. This is the only known way humans can contract Lyme disease, and it is not spread by human contact. When humans contract Lyme disease, they can experience a range of symptoms, including headaches, exhaustion, fever, and a ring-shaped skin rash called erythema that can expand to look like a bull’s eye. Other more serious symptoms can occur, like joint pain. If the disease is left untreated for a few months, a person can even develop neurological problems such as inflamed membranes around the brain, temporary paralysis, numbness, and weakened muscles.

A doctor typically prescribes antibiotics to treat this disease. Many cases of Lyme disease can be resolved with antibiotics, but prevention is a person’s best bet to avoid the disease. Insect repellent, checking for ticks, applying pesticides, and other solutions can help keep ticks away from humans.

Institutions like the National Institute of Allergy and Infectious Diseases (NIAID) are researching Lyme disease to find better ways to diagnose and treat it in humans.

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Tyson Brown, National Geographic Society
National Geographic Society
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Jeanna Sullivan, National Geographic Society
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Sarah Appleton, National Geographic Society, National Geographic Society
Margot Willis, National Geographic Society
Last Updated

October 19, 2023

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