The main vector or carrier of Lyme disease in North America is Ixodes scapularis, the black-legged tick, also known as the deer tick, and in some parts of the US as the bear tick.
Where Do Deer Ticks Live?
Deer ticks thrive in cool Northern latitudes, which would explain why the Northeastern US is ‘Lyme central’, with the majority of cases being reports in 14 states, from Maine south to Virginia, and out west to Minnesota.
They like cool wooded areas and tall grass. They are resistant to cold, and live about 2 years, so they can infect anyone at any time, even in winter, though the largest number of cases are reported in spring and summer every year.
Bacteria They Can Carry
Ticks feed on mammals, reptiles and amphibians, so they can pick up various bacteria, including Borrelia burgdorferi, the main cause of Lyme disease.
Around 30% of those with Lyme disease also show signs of co-infection, that is, other diseases in addition to Lyme. The most common tickborne diseases in the US include:
- Anaplasmosis/ Ehrlichiosis
- Babesiosis
- Bartonella
- Mycoplasma
- Rocky Mountain spotted fever (RMSF)
- Tickborne relapsing fever
Rocky Mountain Spotted Fever can be deadly if not treated in a timely manner.
Ixodes scapularis can also carry and transmit several other parasites, including Theileria microti, which causes the disease babesiosis, and Anaplasma phagocytophilum which causes human granulocytic anaplasmosis (HGA). Up to 40% of those with Lyme will be co-infected with babesiosis, and up to 12% with HGA.
About 55% of ticks studied by the CDC in a lab in New Jersey were carriers of at least one tickborne illness. Fortunately, a tick usually has to be latched onto a human for some time to transmit Lyme, usually from 24 to 36 hours.
Despite the name deer tick, deer can’t transmit Borrelia bacteria to ticks. The bacteria is usually derived from infected mice and other small rodents. However, ticks prefer to live on deer, so any area with a deer population is likely to have a high tick population as well. ‘
The natural predators of ticks include guineafowl, chickens and fire ants, which can help keep down a local population of ticks, and therefore reduce the risk of transmission of Lyme disease.
Lyme disease is a difficult disease to eradicate because of the nature of the bacteria, which are known as spirochetes. They are shaped like corkscrews, so can ‘burrow’ into tissue. Even after treatment, they can still linger, and cause a range of symptoms, including those that resemble arthritis and dementia. Lyme can also affect the heart, leading to a condition known as Lyme carditis, which impairs the function of the heart and can lead to death.
Know Your Ticks
A good tick identification site with clear images can show you what to check for after you have been outdoors. An infant tick, known as a nymph, is the most common cause of Lyme because it is so tiny it makes it difficult to see, which means it can latch on and remain for many hours unnoticed. It is about the size of a poppy seed. Look for unusual spots.
An adult tick is about the size of a sesame seed, until it engorges with blood. It will look like a mole or skin tag that is pearly gray in color.
Other Carriers
In addition to deer ticks, there is some indication that Lyme could be transmitted by mosquitoes, fleas, or lice, but the lion’s share of cases are from deer ticks.
Prevention is the best cure. Use DEET-based insect repellent, and wear long sleeves and long pants when going out in the woods. Tuck the pants into your socks to prevent ticks from getting up the pant legs.
