What is Lyme Disease?
Lyme disease (LD) is a multi-system bacterial infection caused by the spirochete Borrelia burgdoferi (Bb). The pathogen was named in honor of the discoverer and founding board member of the Lyme Disease Foundation, Willy Burgdorfer, Ph.D., M.D.
Research has proven that the bacterium that causes Lyme disease has been in the U.S. for over 100 years.
These spirochetes are maintained in nature in the bodies of wild animals and are transmitted from one animal to another through the bite of an infective tick. Humans and pets are incidental hosts to ticks.
The body does not maintain a natural immunity to the disease. Thus a person can be re-infected with the disease on subsequent tick bites.
What type of ticks transmit Lyme disease?
Lyme disease is transmitted by the bite of an infective tick.
Ticks go through four life stages: egg, larva, nymph and adult. They evolve from one life stage to another by molting Each of the last three stages (the "active" life stages) requires a blood meal. If the tick feeds on an infected host animal, the tick becomes infected. Ticks that transmit Lyme disease can retain the infection throughout their life and are able to transmit the infection to subsequent hosts. This ability to pass the infection on to other hosts makes the tick "infective." Adult ticks generally do not pass the spirochete on to the next generation.
Transmitters of the bacteria in North America include the Western black-legged (Ixodes pacificus) tick in the West and the black-legged tick (Ixodes scapularis) in the rest of the country. The black-legged tick was temporarily known as the "deer" tick (Ixodes "dammini"). Research is underway to determine if the lone star tick (Amblyomma americanum) may also transmit the infection.
Other host-specific ticks may play a minor role in maintaining the infection in nature. This creates a type of "bi-cycle". One cycle being animal-tick-animal feeding and the other cycle being animal-tick-human feeding. The wood rat (Ixodes neotomae) and the rabbit tick (Haemaphysalis leporispalustris) are two examples of ticks that may maintain the infection in nature but do not transmit it to humans. These ticks feed almost exclusively on the hosts mentioned in their common name.
In other parts of the world, other ticks are responsible for transmitting the disease to people, such as the sheep tick (Ixodes ricinus) in Europe and the Taiga tick (Ixodes persulcatus) in Asia.
These ticks can be anywhere: in the woods, by the seashore or even in your backyard.
While ticks can bite year-round, peak tick season in the northeast is April to September, and on the West coast November to April. Ticks can survive under a variety of conditions as long as adequate moisture is available.
An infective tick must be attached to the host for a day or more before transmission of Bb occurs. However, a systematically infected tick or improper tick removal may cause transmission of Lyme Disease much sooner.
Tick infection rates vary geographically and from one year to another.
Symptoms of Lyme Disease
Early localized disease
Signs and symptoms of Early Local Lyme Disease often start with flu-like feelings of headache, stiff neck, fever, muscle aches and fatigue. About 60% of light-skinned patients notice a unique enlarging Lyme disease rash, referred to as erythema migrans (EM), in the days and weeks following the bite. On dark-skinned people, this rash resembles a bruise.
The Lyme disease rash may appear within a day of the bite or as late as a month after. This rash may start as a small, reddish bump about one-half inch in diameter. It may be slightly raised or flat. It soon expands outward, often leaving a clearing (normal flesh color) in the center. It can enlarge to the size of a thumb-print or cover a person's back.
To be considered local disease, the Lyme disease rash must be at the tick bite site with no other major organ system involvement. A Lyme disease rash occurring at other than the bite site in an indication of Disseminated Lyme Disease.
Don't confuse a local reaction to a tick bite with signs of infection. A small, inflamed skin bump or discoloration that develops within hours of a bite and over the next day or two is not likely to be due to infection but rather a local reaction to the disruption of the skin.
Disseminated Lyme disease
Some people do not notice these early symptoms of Lyme disease of infection. Early manifestations usually disappear, and disseminated (other organ system involvement) infection may occur. General symptoms alone do not indicate Lyme disease.
Profound fatigue, severe headache, fever(s), severe muscle aches/pain.
Nerve conduction defects (weakness/paralysis of limbs, loss of reflexes, tingling sensations of the extremities - peripheral neuropathy), severe headaches, stiff neck, meningitis, cranial nerve involvement (e.g., change in smell/taste; difficulty chewing, swallowing, or speaking; hoarseness or vocal cord problems; facial paralysis - Bell's palsy; dizziness/fainting; drooping shoulders; inability to turn head; light or sound sensitivity; change in hearing; deviation of eyeball [wandering or lazy eye], drooping eyelid), stroke, abnormal brain waves or seizures, sleep disorders, cognitive changes (memory problems, difficulty in word finding, confusion, decreased concentration, problems with numbers) and, behavioral changes (depression, personality changes).
Other psychiatric manifestations that have been reported in the scientific literature include panic attacks; disorientation; hallucinations; extreme agitation; impulsive violent, manic or obsessive behavior; paranoia; schizophrenic-like states; dementia; and eating disorders. Several patients have committed suicide.
Vision changes include blindness, retinal damage, optic atrophy, red eye, conjunctivitis, "spots" before eyes, inflammation of various parts of the eye, pain and double vision.
Rash not at the bite site (EM) - This skin discoloration varies in size and shape; usually it has rings of varying shades, but can be uniformly discolored; it may be hot to the touch or itch; it ranges in color from reddish to purple to bruised-looking; and can be necrotic (crusty/oozy). The rash may develop a bull's-eye or target look. The shape may be circular, oval, triangular or a long-thin ragged line.
Heart and blood vessels
Irregular beats, heart block, myocarditis, chest pain, vasculitis.
Pain--intermittent or chronic--usually not symmetrical; sometimes swelling; TMJ-like pain in jaw.
Mild liver function abnormalities.
Difficulty breathing, pneumonia.
Pain, inflammation, cramps, loss of tone.
Stomach and intestines
Nausea, vomiting, diarrhea, loss of appetite, anorexia.
Miscarriage, premature birth, stillbirth and neonatal deaths (rare). Congenital LD has been described in medical literature. It is possible for the bacterium to pass from mother to fetus across the placenta, resulting in congenitally acquired LD. A link between LD and adverse outcomes in pregnancy is under investigation. However, most studies show that mothers who are promptly diagnosed and treated appear to have perfectly normal babies.
Regarding nursing women with LD, there have been no proven cases of transmission through human milk. However, there is research demonstrating that Bb can be found in the colostrum of infected cows and mice. Animal studies have demonstrated that ingestion of Bb can result in infection. Some physicians recommend that nursing mothers discard breast milk during active infection. Breast feeding can resume after treatment is completed and the woman becomes symptom-free. The decision to do so should be discussed with your physician.
For more information, obtain the following information from your local medical library: Klein (1995) Infectious Diseases of the Fetus and Newborn. Chapter by Dr. Tess Gardner, "Lyme disease." New York, NY. Remington-Saunders, p.447-528.