Not all ticks carry the Borrelia burgdorferi bacterium responsible for Lyme disease, and if you live in, or intend to travel through an area with a risk of Lyme disease it is important you understand which species of ticks are potentially harmful so that if you do get bitten you can take the appropriate action.
Deer Ticks
Those ticks that primarily carry the Borrelia burgdorferi bacterium are blacklegged ticks (Ixodes scapularis), also known as deer or bear ticks, and these are very small when they are not engorged (around the size of a pinhead), and when they have fed they swell to around the size of the tip of a pen. The female is slightly larger and reddish brown and the male darker brown in color, and they are very difficult to spot on household pets. Deer ticks live in the woodland and forest in dense, cool underground, leaf litter and brush and feed mainly on mammals such as rodents and deer, and because they predominantly live on the woodland edges and in densely landscaped residential areas they can regularly come into contact with humans. Deer ticks wait near ground level for passing prey, and can latch onto your feet, legs and ankles as you brush past, crawling upwards until they find a spot to bite you. Lyme disease can be treated with oral or injected antibiotics, and early diagnosis and treatment is essential as this disease can cause serious complications such as Lyme arthritis and problems with the heart and nervous system.
Western blacklegged Ticks
Western blacklegged ticks (Ixodes Pacificus) are physically very similar to the blacklegged deer tick, and are also known to carry the Borrelia burgdorferi bacterium that causes Lyme disease and are found in the same kinds of habitats and also throughout more open grasslands.
Brown Dog Ticks
Brown Dog ticks (Rhipicephalus Sanguineus) are a slightly larger species and are much easier to spot, and when they are engorged they form a visible, grey/green color blob, about the size of a fingernail. They are not known for carrying the Borrelia burgdorferi bacterium, but they can transmit Ehrlichiosis to both pets and humans, which can cause fever, fatigue and lameness. Ehrlichiosis can be treated with antibiotics, and it is important to diagnose the condition early as it can cause serious blood related problems in vulnerable people such as young children and older adults. Brown dog ticks can be found in grassy and wooded areas and anywhere dogs are kept including kennels and barns.
American Dog Ticks
American Dog ticks (Dermacentor variabilis) do not carry the Borrelia burgdorferi bacterium, but they can transmit other diseases to both pets and humans such as Rocky Mountain Spotted Fever (RMSF), which is caused by the Rickettsia rickettsii bacterium, and symptoms include fever, nausea, vomiting, and severe headaches, and this can be treated effectively with antibiotics. American dog ticks can be found in grassy areas, meadows and woodland.
Lone Star Ticks
Lone Star ticks (Amblyomma Americanum) are also known as seed ticks, and are similar in size to dog ticks but they have a distinctive white blob on their backs. There is some debate over whether or not Lone star ticks carry the Borrelia burgdorferi bacterium, but they have been confirmed as carriers for Ehrlichiosis and RMSF. Lone star ticks live mostly in wooded areas with ground cover and brush, and are also found along creeks and rivers




An Ixodia tick is a very small tick which is much smaller than dog or cat ticks. The juvenile deer tick is about the size of a pinhead, the biggest adult deer tick can grow to about three-sixteenths of an inch.


