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What is Lyme disease?
Lyme disease is a bacterial illness caused by a bacterium called a "spirochete," which may be transmitted to humans by the bite of infected ticks (Ixodes scapularis and Ixodes pacificus). The actual name of the bacterium in the United States is Borrelia burgdorferi. In Europe, another bacterium, Borrelia afzelii, also causes Lyme disease.
What causes Lyme disease?
Certain ticks, found on deer, harbor the bacterium in their stomachs. Lyme disease is spread by these ticks when they bite the skin, which permits the bacterium to infect the body. Lyme disease is not contagious from an infected person to someone else. Lyme disease can cause abnormalities in the skin, joints, heart, and nervous system.
What is the history of Lyme disease?
Interestingly, the disease only became apparent in 1975, when mothers of a group of children who lived near each other in Lyme, Connecticut, made researchers aware that their children all were diagnosed with rheumatoid arthritis. This unusual grouping of illness that appeared "rheumatoid" eventually led researchers to the identification of the bacterial cause of the children's condition, what was then called "Lyme disease" in 1982.
Where is Lyme disease found?
The number of cases of the disease in an area depends on the amount of ticks in an area and how many are infected with the Lyme bacteria. In certain areas of New York, where Lyme disease is common, over half of the ticks are infected. Lyme disease has been reported most often in the northeastern United States, but it has been reported in all 50 states, as well as China, Europe, Japan, Australia, and parts of the former Soviet Union.
What are the symptoms and signs of Lyme disease?
Lyme disease affects different areas of the body in varying degrees as it progresses and is medically described in three phases: (1) early localized disease with skin inflammation; (2) early disseminated disease with heart and nervous-system involvement, including palsies and meningitis; and (3) late disease featuring motor and sensory-nerve damage and brain inflammation and arthritis. Let's take a look at each phase.
Phase 1: Early localized disease
The site where the tick bites the body is where the bacteria enter through the skin. Within days to weeks of the tick bite, the local skin around the bite develops an expanding ring of flat redness. There may be an outer ring of brighter redness and a central area of clearing, leading to a bull's-eye or target appearance. This classic initial rash is called "erythema migrans." Multiple secondary lesions can occur that are a reaction to the infection and are not due to multiple tick bites. Patients often can't recall the tick bite (the ticks can be as small as the periods in this paragraph). Also, they may not have the identifying rash to signal the doctor. More than one in four patients never develops a rash. The redness of the skin is often accompanied by generalized fatigue, muscle and joint stiffness, swollen glands, and headache resembling symptoms of a viral infection. Later, it can produce abnormalities in the joints, heart, and nervous system.
Phase 2: Early disseminated disease
The redness resolves, without treatment, in about a month. Weeks to months after the initial redness of the skin, the bacterium and its effects can spread throughout the body, subsequently causing disease in the joints, heart, and nervous system.
Phase 3: Late disease
The later phases of Lyme disease can affect the heart, causing inflammation of the heart muscle. This can result in abnormal heart rhythm and heart failure. The nervous system can develop facial-muscle paralysis (Bell's palsy), abnormal sensation due to disease of peripheral nerves (peripheral neuropathy), meningitis, and confusion. Arthritis, or inflammation in the joints, begins with swelling, stiffness, and pain. Usually, only one or a few joints become affected, most commonly the knees. The arthritis of Lyme disease can look like many other types of inflammatory arthritis and can become chronic.
How is Lyme disease diagnosed?
In early Lyme disease, doctors can sometimes make a diagnosis simply by finding the classic red rash, particularly in people who have recently been in regions in which Lyme disease is common. The doctor might review the patient's history and examine the patient in order to exclude diseases with similar findings in the joints, heart, and nervous system. Blood testing for antibodies to Lyme bacteria is generally not necessary or helpful in early stage disease, but it can help with diagnosis in later stages. Antibodies are produced by the body to attack the bacteria and can be evidence of exposure to the bacteria. These antibodies can be detected using a laboratory method called an ELISA assay. Antibodies, however, can be false indicators of disease, since they can remain for years after the disease is cured. Currently, the confirmatory test that is most reliable is referred to as the Western blot assay.
What is the treatment for Lyme disease?
Most Lyme disease is curable with antibiotics. The type of antibiotic depends on the stage of the disease (early or late) and what areas of the body are affected. Early illness is usually treated with oral medicines, for example, doxycycline (Vibramycin), amoxicillin (Amoxil), or cefuroxime axetil (Ceftin). Therefore, if a person finds a typical bull's-eye skin rash (as described on a previous slide) developing in an area of a tick bite, they should seek medical attention as soon as possible. Generally, antibiotic treatment resolves the rash within one or two weeks. Later illness such as nervous-system disease might require intravenous drugs, for example, ceftriaxone (Rocephin).
What's the treatment for later-stage joint pain of Lyme disease?
For the relief of symptoms, pain-relieving medicines might be given. Swollen joints can be reduced by the doctor removing fluid from them (arthrocentesis). An arthrocentesis is a procedure whereby fluid is removed from a joint using a needle and syringe under sterile conditions. It is usually performed in a doctor's office. Rarely, even with appropriate antibiotics, the arthritis continues. It has been suggested by researchers that sometimes joint inflammation can persist even after eradication of the Lyme bacterium. The doctor also can use oral medications, such as ibuprofen (Motrin, Nuprin) to reduce inflammation and improve function.
How can Lyme disease be prevented?
Because Lyme disease is transmitted by ticks attaching to the body, it is important to use tick-bite avoidance techniques when visiting known tick areas. Spraying insect repellant containing DEET onto exposed skin can help. Wearing long clothing can protect the skin. Clothing, children, and pets should be examined for ticks. Ticks can be removed gently with tweezers and saved in a jar for later identification. Bathing the skin and scalp and washing clothing upon returning home might prevent the bite and transmission of the disease.
Is there a vaccine for Lyme disease?
Vaccines were on the market, however, on Feb. 25, 2002, the manufacturer announced that the LYMErix™ Lyme disease vaccine would no longer be commercially available. Further studies of vaccines are needed. For now, ideal prevention focuses on the recommendations of the preceding slide.
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