Information about Lyme Disease
Lyme disease, transmitted by the black-legged (deer) tick, is the most common vector-borne disease in the US and the number of cases continues to rise every year. Although Lyme disease has been reported in all fifty states, it is most prevalent in the Northeast, North Central and the West Coast areas.
Life cycle of the black-legged tick:
Deer ticks have a two year life cycle and must feed three times – during the larval, nymphal, and adult stage. In the spring, the adult female tick lays thousands of eggs on the ground. During the summer months the eggs hatch into larvae and require a meal. The larvae attach to a small animal or bird, which if infected with the Lyme disease bacterium, transfers the bacteria to the tick along with the blood the tick is feeding on. Once infected, the tick remains infected for the rest of its life. After feeding, the larvae become inactive until the following spring while they molt into nymphs. The nymphs, active during both the spring and summer months, usually feed on small animals, but they will attach to pets and humans and this is the time when most humans become infected. The nymphs molt again into reddish-brown adults and need one more meal to reproduce. They prefer to feed on deer, but will also feed on humans and pets. Once fed, the male deer tick dies after mating with the female and the female dies after she lays her eggs; the life-cycle is now complete. Interestingly, the deer do not become infected, but provide a means for transporting the ticks to surrounding areas of the environment.
Lyme disease symptoms:
Once the bacterium has been transferred to a human, it can affect several parts of the body and produce different symptoms at different times. Not everyone will experience the same symptoms.
Most common symptom is a circular rash (Erythema migrans) - it begins at the site of the tick bite, gradually expands over several days, and usually occurs between 3 and 30 days after the bite. The center of the rash may clear as it becomes larger leaving red margins, thus producing a “bull’s eye” appearance. It is not usually painful, but may be warm to the touch.
Other symptoms may include:
- Muscle and joint aches
- Swollen lymph nodes
If untreated or improperly treated, Lyme disease may spread to other parts of the body, producing different symptoms. These may include:
- Arthritis - pain and swelling of the joints, especially the knees
- Central nervous system symptoms - numbness, pain, nerve paralysis (often of the facial muscles and, maybe, only on one side), and meningitis (fever, stiff neck, and severe headache)
- Heart rhythm irregularities – these are rare
- Problems with memory or cognition, fatigue, headache, and sleep disturbances sometimes persisting after treatment.
Early treatment of Lyme disease symptoms is very important so it is important to check with your health care provider if you suspect you have Lyme disease. Most cases can be treated successfully with a few weeks of antibiotics especially if begun early in the course of the disease.
Stages of the Deer tick