The American dog tick, or Dermacentor variabilis, is a widespread tick species across North America. While a bite is not an automatic cause for alarm, this particular tick is a known carrier for several diseases that can affect humans. Understanding the risks involves recognizing the tick, knowing the illnesses it can transmit, and being aware of the appropriate actions to take following a bite.
Identifying the American Dog Tick and Its Habitat
The American dog tick is one of the most frequently encountered ticks, especially in the eastern United States. Adult females are identifiable by a large, off-white shield, or scutum, located behind their head against a dark brown body. Males have mottled or streaked whitish-gray markings covering their entire back. Before feeding, these ticks are flat and oval-shaped, but become larger and grayish when engorged with blood.
This species thrives in areas with little to no tree cover, making grassy fields, scrubland, and the edges of walking trails its preferred habitats. You are most likely to encounter them in low-lying vegetation and tall grass where they wait for a host. Their geographic range covers most of North America east of the Rocky Mountains, with some populations also found on the Pacific Coast. They are most active during the warmer months, from April through August.
Key Diseases Transmitted
Rocky Mountain Spotted Fever (RMSF)
The most serious disease transmitted by the American dog tick is Rocky Mountain spotted fever. This illness is caused by the bacterium Rickettsia rickettsii, which infects the cells lining blood vessels. Transmission can occur within hours of a tick bite. Early symptoms often begin two to fourteen days after the bite and are nonspecific, including a sudden high fever, severe headache, and muscle pain.
A characteristic spotted rash often develops a few days after the fever starts, typically beginning on the wrists and ankles before spreading to the rest of the body. However, this rash does not always occur, and waiting for it to appear before seeking treatment can be dangerous. RMSF progresses rapidly and can lead to serious complications or death if not treated early with antibiotics, such as doxycycline.
Tularemia
Another bacterial disease spread by the American dog tick is tularemia, caused by Francisella tularensis. Though less common than RMSF, it can cause a serious illness. Symptoms typically appear three to five days after exposure and can vary depending on how the bacteria entered the body. When transmitted by a tick bite, it often presents as ulceroglandular tularemia.
This form is characterized by a skin ulcer that develops at the site of the bite. Other common symptoms include fever, chills, and painfully swollen lymph glands, usually in the armpit or groin area nearest to the bite. Like RMSF, tularemia requires treatment with antibiotics to prevent more severe complications.
Responding to a Bite and Seeking Medical Care
If you find an American dog tick attached to your skin, it is important to remove it correctly and promptly. Use fine-tipped tweezers to grasp the tick as close to the skin’s surface as possible. Pull upward with steady, even pressure, avoiding twisting or jerking motions that could cause the tick’s mouthparts to break off in the skin. Do not use folk remedies like nail polish, petroleum jelly, or heat, as these methods are ineffective and may agitate the tick, causing it to release more saliva.
After removing the tick, thoroughly clean the bite area and your hands with rubbing alcohol or soap and water. Monitor your health for up to 30 days following the bite. Contact a healthcare provider if you are unable to remove the tick completely or if you develop any symptoms such as a rash, fever, headache, or muscle aches. Early diagnosis and treatment are important for a positive outcome.
Prevention Strategies
Taking proactive steps is the most effective way to avoid diseases carried by the American dog tick. Use an EPA-registered insect repellent containing ingredients like DEET or picaridin on exposed skin. Treat clothing and gear with products containing permethrin. Wearing light-colored clothing can make it easier to spot ticks before they attach.
Modifying your immediate environment can also reduce your risk. Keep lawns mowed, remove leaf litter, and clear tall grasses and brush from around your home and at the edge of your yard. These landscaping practices help minimize the places where ticks and their primary hosts, such as rodents, can live and breed.
After any outdoor activity, conduct a thorough check of your entire body. Pay special attention to areas like:
- Under the arms
- In and around the ears
- Inside the belly button
- Behind the knees
- In the hair
Remember to also check your children and pets, as they can bring ticks into the home. Promptly washing clothes worn outdoors in hot water can also help kill any ticks that may have come inside.