Ticks can transmit disease to both humans and animals.
"Lyme disease is the most common tick-borne illness in North America and Europe. Lyme
disease is caused by the bacterium Borrelia burgdorferi. Deer ticks, which feed on the blood of
animals and humans, can harbor the bacteria and spread it when feeding.
You're more likely to get Lyme disease if you live or spend time in grassy and heavily wooded
areas where ticks carrying the disease thrive. It's important to take common-sense precautions
in areas where Lyme disease is prevalent.
If you're treated with appropriate antibiotics in the early stages of the disease, you're likely to
recover completely. In later stages, response to treatment may be slower, but the majority of
people with Lyme disease recover completely with appropriate treatment."
-Mayo Clinic: Lyme Disease
"Ehrlichiosis is a bacterial illness transmitted by ticks that causes flu-like symptoms. The
signs and symptoms of ehrlichiosis range from mild body aches to severe fever and usually
appear within a week or two of a tick bite. If treated quickly with appropriate antibiotics, it
generally improves within a few days.
Another tick-borne infection - anaplasmosis - is closely related to ehrlichiosis. But the
two have distinct differences and are caused by different microorganisms."
-Mayo Clinic: Ehrlichiosis
The best way to prevent these infections is to avoid tick bites.