Cooperative Extension Service
The University of Georgia College of Agricultural and Environmental Sciences
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Beverly Sparks,
Extension Entomologist
Appreciation to Dr. Burton R. Evans, Extension Entomologist (ret.), who developed
the original publication
It is important to know about ticks for several reasons. They carry Lyme disease and Rocky Mountain spotted fever, and they can cause further infections if their mouthparts break off when the ticks are removed. If tick populations are high in recreation and camping areas, participation may drop off causing monetary loss to the leisure industry. Costs to control ticks -- in yards, homes, on pets and yourself -- can run high.
The three species of ticks occurring throughout Georgia that commonly feed on humans are the lone star tick (Amblyomma americanum), American dog tick (Dermacentor variabilis) and black-legged tick (Ixodes scapularis).
The lone star tick has unusually long mouthparts. The female has a single white spot in the middle of her back, while the white markings on the male are diffuse. Common large hosts are livestock, dogs, deer and humans as well as smaller hosts such as birds and rodents.
The American dog tick has shorter mouthparts. Both the male and female have diffuse white markings on the back. The dog is the preferred host, but the tick will feed on a variety of large animals, including humans.
The black-legged tick is smaller than the other two ticks and has no white markings on the back. This tick is common on white-tailed deer, dogs, birds, humans and other large mammals as well as a variety of small rodents.
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| Figure 1. Lone start tick | Figure 2. American dog tick | Figure 3. Black-legged tick |
All three ticks go through a similar life cycle. Each stage in the tick's life cycle must have a blood meal for the tick to mature into an adult and lay eggs for the next generation. The adult female is fertilized by the male while she is engorging with blood on her last host. She will then drop off the host and, in about 3 to 10 days, begin laying 4,000 to 6,000 eggs in a mass.
The eggs will hatch within two weeks up to several months, depending on the environment, into the six-legged larvae or "seed ticks." The reason you may get a large number of seed ticks on your body is because of their concentration in the area where the eggs were laid. Ticks are very adept in locating a host by detecting the carbon dioxide that is exhaled and body warmth.
The "seed" or larval ticks will typically climb up a blade of grass and wait for a host - usually a small rodent. After engorging with blood, the larval tick will drop off the host, shed its skin and change into an eight-legged nymph. The nymph will seek another host, engorge with blood, drop off, shed its skin and develop into the adult stage. The adult usually prefers a large animal such as a deer, horse, dog or human. The feeding is usually done without pain and may take several days for completion. The larval, nymph and adult tick can each survive up to a year waiting for a host.
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| Figure 4. Life cycle of tick |
Ticks survive best in high grass or brush areas that are also attractive to their hosts. These are the areas you are most likely to encounter a tick. Game trails and large deer populations are often associated with large tick populations. Ticks need a high level of moisture for survival. Dehydration from hot, dry weather combined with short grass that has little or no mulch can be fatal to ticks.
The American dog tick feeds on humans only in the adult stage. All three stages of the lone star and black-legged ticks will feed on humans.
Lyme disease is fairly new to Georgia. Only four cases were reported when it first appeared in 1987. While cases occur all over the state, the largest numbers are in the northern half of the state. The black-legged tick seems to be the major vector, especially in the nymphal stage. Its small size (1/16 inch) probably contributes to failure to detect the nymph while feeding.
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| Figure 5. Actual black-legged tick size |
The cause of Lyme disease is Borrellia burgdorferi, a bacteria. The initial sign of infection with Lyme disease is a ring-like swollen rash, known as "erythema migrans," at the site of the tick bite 3 to 22 days following the bite of an infected tick. There is usually a bright red outer ring with the center of the rash being lighter. The rash is frequently accompanied by flu-like symptoms (fever, headache, stiff neck, muscle pain and sometimes nausea) and joint pain. While the rash is very helpful in diagnosis, not all cases develop it. If you develop flu-like symptoms, joint pain or a rash in a few days to a month after a tick bite, consult your physician for a diagnosis.
A blood test can help confirm the disease. It needs to be taken three to six weeks after symptoms develop. If taken too soon for antibodies to develop, the test may show a false negative. While desirable to begin antibiotic treatment soon after symptoms develop, this can also produce a false negative. Lyme disease is easily treated in the early stages with antibiotics; if delayed, treatment can be more difficult.
The later stages of Lyme disease begin weeks or even years later and can be very serious. It is easily misdiagnosed because it mimics a variety of cardiovascular, arthritic and neurological diseases. Joint pain can be severe with permanent destruction of bone and cartilage of the joints. No deaths have been reported due to initial infection, but complications may affect the lifespan of some individuals. Personal protection and early diagnosis and treatment are your best defense against Lyme disease.
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| Figure 6. Typical rash of Lyme disease |
The second important tick-borne disease is Rocky Mountain spotted fever, caused by Rickettsia rickettsii, a rickettsial or bacteria-like organism. It is characterized by a sudden onset of chills, fever, headache and bloodshot eyes. The name "spotted fever" refers to the rash that appears two to four days after the onset of fever. The rash characteristically starts on the hands and feet and gradually spreads to most of the body. It is easily misdiagnosed as measles. Diagnosis is aided by a history of a recent tick bite and confirmed by a blood test. The fatality rate is about 5 percent. Antibiotics give good treatment. The American dog tick and lone star tick are the major vectors.
The best way to avoid tick bites when on wooded trails, in high grass or brush areas is to take some personal precautions.
Around your house, you can treat your dog with an approved pesticide for ticks, keep the grass cut short, fence the yard to keep out other dogs that bring ticks in, and use a pesticide in the yard as needed to reduce tick populations. (Contact your county extension office for specific recommendations.) The dog can serve as a reservoir for both Lyme disease and Rocky Mountain spotted fever. While the dog does not seem to be affected by Rocky Mountain spotted fever, it can suffer joint pain from Lyme disease.
Georgia is blessed with beautiful outdoor recreation areas, and its citizens should continue to enjoy them. Taking a few precautions and being aware of the symptoms of Lyme disease and Rocky Mountain spotted fever should give you good protection against ticks.
Trade names are used only for information. The Cooperative Extension Service, the University of Georgia College of Agricultural & Environmental Sciences, does not guarantee or warrant published standards on any product mentioned; neither does the use of a trade or brand name imply approval of any product to the exclusion of others that may also be suitable.
Leaflet 417/Reprinted January, 2002
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