Lyme disease

Lyme disease is a bacterial illness caused by a bacterium called a "spirochete." In the United States, the actual name of the bacterium is Borrelia burgdorferi. In Europe, another bacterium, Borrelia afzelii, also 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 affected person to someone else. Lyme disease can cause abnormalities in the skin, joints, heart, and nervous system.
SIGNS AND TESTS
A blood test can be done to check for antibodies to the bacteria that cause Lyme disease. The most commonly used is the ELISA for Lyme disease test. A western blot test is done to confirm ELISA results.
In areas where Lyme disease is more common, your health care provider may be able to diagnose early disseminated Lyme disease (Stage 1) without doing any lab tests.
Other tests that may be done, when the infection has become more widespread, include:
-Electrocardiogram
-Echocardiogram to look at the heart
-Spinal tap (lumbar puncture to examine spinal fluid
-MRI of the brain
SYMPTOMS
In the early stages of Lyme disease, you may experience flu-like symptoms that can include a stiff neck, chills, fever, swollen lymph nodes, headaches, fatigue, muscle aches, and joint pain. You also may experience a large, expanding skin rash around the area of the tick bite. In more advanced disease, nerve problems and arthritis, especially in the knees, may occur.
Erythma migrans. Erythema migrans is the telltale rash which occurs in about 70% to 80% of cases and starts as a small red spot that expands over a period of days or weeks, forming a circular, triangular, or oval-shaped rash. Sometimes the rash resembles a bull's-eye because it appears as a red ring surrounding a central clear area. The rash, which can range in size from that of a dime to the entire width of a person's back, appears between three days and a few weeks of a tick bite, usually occurring at the site of a bite. As infection spreads, several rashes can appear at different sites on the body.
Erythema migrans is often accompanied by symptoms such as fever, headache, stiff neck, body aches, and fatigue. These flu-like symptoms may resemble those of common viral infections and usually resolve within days or a few weeks.
Arthritis. After several weeks of being infected with Lyme disease, approximately 60% of those people not treated with antibiotics develop recurrent attacks of painful and swollen joints that last a few days to a few months. The arthritis can shift from one joint to another; the knee is most commonly affected and usually one or a few joints are affected at any given time. About 10% to 20% of untreated patients will go on to develop lasting arthritis. The knuckle joints of the hands are only very rarely affected.
Neurological symptoms. Lyme disease can also affect the nervous system, causing symptoms such as stiff neck and severe headache (meningitis), temporary paralysis of facial muscles (Bell's palsy), numbness, pain or weakness in the limbs, or poor coordination. More subtle changes such as memory loss, difficulty with concentration, and a change in mood or sleeping habits have also been associated with Lyme disease. People with these latter symptoms alone usually don't have Lyme disease as their cause.
Nervous system abnormalities usually develop several weeks, months, or even years following an untreated infection. These symptoms often last for weeks or months and may recur. These features of Lyme disease usually start to resolve even before antibiotics are started. Patients with neurologic disease usually have a total return to normal function.
Heart problems. Fewer than one out of 10 Lyme disease patients develops heart problems, such as an irregular, slow heartbeat, which can be signaled by dizziness or shortness of breath. These symptoms rarely last more than a few days or weeks. Such heart abnormalities generally appear several weeks after infection, and usually begin to resolve even before treatment.
Other symptoms. Less commonly, Lyme disease can result in eye inflammation and severe fatigue, although none of these problems is likely to appear without other Lyme disease symptoms being present.
Lyme disease imitates a variety of illnesses and its severity can vary from person to person. If you have been bitten by a tick and live in an area known to have Lyme disease, see your doctor right away so that a proper diagnose can be made and treatment started
Pathophysiology
Borrelia burgdorferi can spread throughout the body during the course of the disease, and has been found in the skin, heart, joint, peripheral nervous system, and central nervous system.Many of the signs and symptoms of Lyme disease are a consequence of the immune response to the spirochete in those tissues. B. burgdorferi is injected into the skin by the bite of an infected Ixodes tick. Tick saliva, which accompanies the spirochete into the skin during the feeding process, contains substances that disrupt the immune response at the site of the bite. This provides a protective environment where the spirochete can establish infection. The spirochetes multiply and migrate outward within the dermis. The host inflammatory response to the bacteria in the skin causes the characteristic circular EM lesion. Neutrophils, however, which are necessary to eliminate the spirochetes from the skin, fail to appear in the developing EM lesion. This allows the bacteria to survive and eventually spread throughout the body.
Days to weeks following the tick bite, the spirochetes spread via the bloodstream to joints, heart, nervous system, and distant skin sites, where their presence gives rise to the variety of symptoms of disseminated disease. The spread of B. burgdorferi is aided by the attachment of the host protease plasmin to the surface of the spirochete.If untreated, the bacteria may persist in the body for months or even years, despite the production of B. burgdorferi antibodies by the immune system. The spirochetes may avoid the immune response by decreasing expression of surface proteins that are targeted by antibodies, antigenic variation of the VlsE surface protein, inactivating key immune components such as complement, and hiding in the extracellular matrix, which may interfere with the function of immune factors.
A study by Drs. Monica Embers, Stephen Barthold and colleagues has found that Borrelia burgdorferi persist in monkeys after antibiotic treatment. The authors conclude that their studies "offer proof of the principle that intact spirochetes can persist in an incidental host comparable to humans, following antibiotic therapy.” The study also found that the C6 antibody test gave false negative results in all of those treated with antibiotics and in more than 50% of those not treated. The presence of the Borrelia burgdorferi was confirmed by PCR, culture, immunofluorescence, and or xenodiagnosis. Both the lab tests and evidence of persistence are very important for Lyme patients because they show that Bb may persist after treatment even when antibody tests are negative.
In the brain, B. burgdorferi may induce astrocytes to undergo astrogliosis (proliferation followed by apoptosis), which may contribute to neurodysfunction. The spirochetes may also induce host cells to secrete products toxic to nerve cells, including quinolinic acid and the cytokines IL-6 and TNF-alpha, which can produce fatigue and malaise. Both microglia and astrocytes secrete IL-6 and TNF-alpha in the presence of the spirochete. This cytokine response may contribute to cognitive impairment.
In Lyme encephalopathy, diffuse white matter pathology can disrupt grey matter connections, and could account for deficits in attention, memory, visuospatial ability, complex cognition, and emotional status. White matter disease may have a greater potential for recovery than gray matter disease, perhaps because neuronal loss is less common. Resolution of MRI white matter hyperintensities after antibiotic treatment has been observed.A developing hypothesis is that the chronic secretion of stress hormones as a result of Borrelia infection may reduce the effect of neurotransmitters, or other receptors in the brain by cell-mediated proinflammatory pathways, thereby leading to the dysregulation of neurohormones, specifically glucocorticoids and catecholamines, the major stress hormones.This process is mediated via the hypothalamic-pituitary-adrenal axis. Additionally tryptophan, a precursor to serotonin, appears to be reduced within the central nervous system (CNS) in a number of infectious diseases that affect the brain, including Lyme. Researchers are investigating if this neurohormone secretion is the cause of neuropsychiatric disorders developing in some patients with borreliosis.
TREATMENT
Antibiotics are the primary treatment for Lyme disease; the most appropriate antibiotic treatment depends upon the patient and the stage of the disease.[2] According to the Infectious Diseases Society of America (IDSA) guidelines, the antibiotics of choice are doxycycline (in adults), amoxicillin (in children), erythromycin (for pregnant women) and ceftriaxone, with treatment lasting 10 to 28 days. If Lyme arthritis symptoms fail to respond to a 30-day antibiotic regimen, some recommend an additional 30 days of antibiotics. Alternative choices are cefuroxime and cefotaxime. Treatment of pregnant women is similar, but doxycycline should not be used.A double blind, randomized, placebo-controlled multicenter clinical study indicated three weeks of treatment with intravenous ceftriaxone, followed by 100 days of treatment with oral amoxicillin did not improve symptoms any more than just three weeks of treatment with ceftriaxone. The researchers noted the outcome should not be evaluated after the initial antibiotic treatment, but rather 6–12 months afterwards. In patients with chronic posttreatment symptoms, persistent positive levels of antibodies did not seem to provide any useful information for further care of the patient.In later stages, the bacteria disseminate throughout the body and may cross the blood–brain barrier, making the infection more difficult to treat. Late diagnosed Lyme is treated with oral or intravenous antibiotics, frequently ceftriaxone for a minimum of four weeks. Minocycline is also indicated for neuroborreliosis for its ability to cross the blood–brain barrier.
Alternative therapies
A number of other alternative therapies have been suggested, though clinical trials have not been conducted, so the therapies are not known to be scientifically sound. For example, the use of hyperbaric oxygen therapy has been discussed by CAM enthusiasts as an adjunct to antibiotics for Lyme. Though there are no published data from clinical trials to support its use, preliminary results using a mouse model suggest its effectiveness against B. burgdorferi both in vitro and in vivo. Anecdotal clinical research has suggested antifungal azole medications, such as fluconazole, could be used in the treatment of Lyme, but the use of these drugs has yet to be tested in a controlled study.Alternative medicine approaches include bee venom, because it contains the peptide melittin, which has been shown to exert inhibitory effects on Lyme bacteria in vitro; however, no clinical trials of this treatment have been carried out.
PREVENTION
Fortunately, the cause of Lyme disease is known and the disease can be prevented. Essential to prevention is the avoidance of deer ticks. Although generally only about one percent of all deer ticks are infected with the Lyme disease bacterium, in some areas more than half of them harbor the microbe.Most people with Lyme disease become infected during the late spring, summer, and early fall when immature ticks are out looking for their meal. Except in warm climates, few people are bitten by deer ticks during winter months.Deer ticks are most often found in wooded areas and nearby grasslands, and are especially common where the two areas merge, including neighborhood yards where deer occasionally roam. Ticks do not survive long on sunny lawns, they dry out quickly and die.
Try these tips to prevent tick bites:
-Wear long sleeves and tightly woven clothing that is light in color when walking in wooded areas so the ticks can be seen more easily.
-Wear your shirt tucked into your pants, and your pants tucked into your socks or boots.
-Walk in the center of trails through the woods to avoid picking up ticks from overhanging grass and brush.
-Keep grass trimmed as short as possible.
-Apply tick repellents with DEET to your clothing, shoes and socks before going out. Another tick repellent called permethrin, designed to be placed on the clothing can be used alone or in combination with DEET. (Although highly effective, these repellents can cause some serious side effects, particularly when high concentrations are used repeatedly on the skin. Infants and children may be especially at risk for adverse reactions.)
-Check yourself, your family, and your pets routinely for ticks, especially after a trip outdoors.
-Shower and shampoo your hair if you think you may have been exposed to ticks.
-Check your clothes for ticks and wash them immediately in order to remove any ticks.
COMPLICATION
Stage 3, or late disseminated, Lyme disease can cause long-term joint inflammation (Lyme arthritis) and heart rhythm problems. Brain and nervous system problems are also possible, and may include:
-Decreased concentration
-Memory disorders
-Nerve damage
-Numbness
-Pain
-Paralysis of the face muscles
-Sleep disorders
-Vision problems