Kidney Stones
Kidney stones are one of the most painful disorders to afflict humans. This ancient health problem has tormented people throughout history. Scientists have even found evidence of kidney stones in an Egyptian mummy estimated to be more than 7,000 years old. Kidney stones are one of the most common disorders of the urinary tract. More than 1 million cases of kidney stones were diagnosed in 1985. It is estimated that 10 percent of all people in the United States will have a kidney stone at some point in time. Men tend to be affected more frequently than women.
Most kidney stones pass out of the body without any intervention by a physician. Cases that cause lasting symptoms or other complications may be treated by various techniques, most of which do not involve major surgery. Research advances also have led to a better understanding of the many factors that promote stone formation.
An Introduction to the Urinary Tract
The urinary tract, or system, consists of the kidneys, ureters, bladder, and urethra. The kidneys are two bean-shaped organs located below the ribs toward the middle of the back. The kidneys remove extra water and wastes from the blood, converting it to urine. They also keep a stable balance of salts and other substances in the blood. The kidneys produce hormones that help build strong bones and help form red blood cells.
Narrow tubes called ureters carry urine from the kidneys to the bladder, a triangle-shaped chamber in the lower abdomen. Like a balloon, the bladder's elastic walls stretch and expand to store urine. They flatten together when urine is emptied through the urethra to outside the body.
What Is a Kidney Stone?
A kidney stone develops from crystals that separate from urine and build up on the inner surfaces of the kidney. Normally, urine contains chemicals that prevent or inhibit the crystals from forming. These inhibitors do not seem to work for everyone, however, and some people form stones. If the crystals remain tiny enough, they will travel through the urinary tract and pass out of the body in the urine without even being noticed.
Kidney stones may contain various combinations of chemicals. The most common type of stone contains calcium in combination with either oxalate or phosphate. These chemicals are part of a person's normal diet and make up important parts of the body, such as bones and muscles. A less common type of stone is caused by infection in the urinary tract. This type of stone is called a struvite or infection stone. Much less common are the uric acid stone and the rare cystine stone. Urolithiasis is the medical term used to describe stones occurring in the urinary tract. Other frequently used terms are urinary tract stone disease and nephrolithiasis. Doctors also use terms that describe the location of the stone in the urinary tract. For example, a ureteral stone (or ureterolithiasis) is a kidney stone found in the ureter. To keep things simple, the term "kidney stones" is used throughout this e-text document. Gallstones and kidney stones are not related. They form in different areas of the body. If a person has a gallstone, he or she is not necessarily more likely to develop kidney stones.
Who Gets Kidney Stones?
For some unknown reason, the number of persons in the United States with kidney stones has been increasing over the past 20 years. White people are more prone to kidney stones than are black people. Although stones occur more frequently in men, the number of women who get kidney stones has been increasing over the past 10 years, causing the ratio to change. Kidney stones strike most people between the ages of 20 and 40. Once a person gets more than one stone, he or she is more likely to develop others.
What Causes Kidney Stones?
Doctors do not always know what causes a stone to form. While certain foods may promote stone formation in people who are susceptible, scientists do not believe that eating any specific food causes stones to form in people who are not susceptible.
A person with a family history of kidney stones may be more likely to develop stones. Urinary tract infections, kidney disorders such as cystic kidney diseases, and metabolic disorders such as hyperparathyroidism are also linked to stone formation. In addition, more than 70 percent of patients with adequate hereditary disease called renal tubular acidosis develop kidney stones. Cystinuria and hyuperoxaluria are two other rare inherited metabolic disorders that often cause kidney stones. In cystinuria, the kidneys produce too much of the amino acid cystine. Cystine does not dissolve in urine and can build up to form stones. With hyperoxaluria, the body produces too much of the salt oxalate. When there is more oxalate than can be dissolved in the urine, the crystals settle out and form stones.
Absorptive hypercalciuria occurs when the body absorbs too much calcium from food and empties the extra calcium into the urine. This high level of calcium in the urine causes crystals of calcium oxalate or calcium phosphate to form in the kidneys or urinary tract. Other causes of kidney stones are hyperuricosuria (a disorder of uric acid metabolism), gout, excess intake of vitamin D, and blockage of the urinary tact. Certain diuretics (water pills) or calcium-based antacids may increase the risk of forming kidney stones by increasing the amount of calcium in the urine.
Calcium oxalate stones may also form in people who have a chronic inflammation of the bowel or who have had an intestinal bypass operation, or ostomy surgery. As mentioned above, struvite stones can form in people who have had a urinary tract infection.
What Are the Symptoms?
Usually, the first symptom of a kidney stone is extreme pain. The pain often begins suddenly when a stone moves in the urinary tract, causing irritation or blockage. Typically, a person feels a sharp, cramping pain the back and side in the area of the kidney or in the lower abdomen. Sometimes nausea and vomiting occur with this pain. Later, the pain may spread to the groin.
If the stone is too large to pass easily, the pain continues as the muscles in the wall of the tiny ureter try to squeeze the stone along into the bladder. As a stone grows or moves, blood may be found in the urine. As the stone moves down the ureter closer to the bladder, a person may feel the need to urinate more often or feel a burning sensation during urination. If fever and chills accompany any of these symptoms, an infection may be present. In this case, a doctor should be contacted immediately.
How Are Kidney Stones Diagnosed?
Sometimes "silent" stones--those that do not cause symptoms--are found on x-rays taken during a general health exam. These stones would likely pass unnoticed. More often, kidney stones are found on an x-ray or sonogram taken on someone who complains of blood in the urine or sudden pain. These diagnostic images give the doctor valuable information about the stone's size and location. Blood and urine tests help detect any abnormal substance that might promote stone formation.
The doctor may decide to scan the urinary system using a special x-ray test called an IVP (intravenous pyelogram). Together, the results from these tests help determine the proper treatment.
How Are Kidney Stones Treated?
Fortunately, most stones can be treated without surgery. Most kidney stones can pass through the urinary system with plenty of water (2 to 3 quarts a day) to help move the stone along. In most cases, a person can stay home during this process, taking pain medicine as needed. The doctor usually asks the patient to save the passed stone(s) for testing.
The First Step: Prevention
People who have had more than one kidney stone are likely to form another. Therefore, prevention is very important. To prevent stones from forming, their cause must be determined. The urologist will order laboratory tests, including urine and blood tests. He or she will also ask about the patient's medical history, occupation and dietary habits. If a stone has been removed, or if the patient has passed a stone and saved it, the lab can analyze the stone to determine its composition.
A patient may be asked to collect his or her urine for 24 hours after a stone has passed or been removed. The sample is used to measure urine volume and levels of acidity, calcium, sodium, uric acid, oxalate, citrate, and creatinine (a byproduct of protein metabolism). The doctor will use this information to determine the cause of the stone. A second 24-hour urine collection may be needed to determine if the prescribed treatment is working.
Lifestyle Changes. A simple and most important lifestyle change to prevent stones is to drink more liquids--water is best. A recurrent stone former should try to drink enough liquids throughout the day to produce at least 2 quarts of urine in every 24-hour period.
Patients with too much calcium or oxalate in the urine may need to eat fewer foods containing calcium and oxalate.
Not everyone will benefit from a low-calcium diet, however. Some patients who have high levels of oxalate in their urine may benefit from extra calcium in their diet. patients may be told to avoid food with added vitamin D and certain types of antacids that have a calcium base.
Patients who have a very acid urine may need to eat less meat, fish, and poultry. These foods increase the amount of acid in the urine.
To prevent cystine stones, patients should drink enough water each day to reduce the amount of cystine that escapes into the urine. This is difficult because more than a gallon of water may be needed every 24 hours, a third of which must be drunk during the night.
Medical Therapy. The doctor may prescribe certain medications to prevent calcium and uric acid stones. These drugs control the amount of acid or alkali in the urine, key factors in crystal formation. The drug allopurinol may also be useful in some cases of hypercalciuria and hyperuricosuria.
Another way a doctor may try to control hypercalciuria, and thus prevent calcium stones, is by prescribing certain diuretics, such as hydrochlorothiazide. These drugs decrease the amount of calcium released by the kidneys into the urine.
Some patients with absorptive hypercalciuria may be given the drug sodium cellulose phosphate. This drug binds calcium in the intestine and prevents it from leaking into the urine.
If cystine stones cannot be controlled by drinking more fluids, the doctor may prescribe the drug Thiola. This medication helps reduce the amount of cystine in the urine.
For struvite stones that have been totally removed, the first line of prevention is to keep the urine free of bacteria that can cause infection. The patient's urine will be tested on a regular basis to be sure that bacteria are not present.
If struvite stones cannot be removed the doctor may prescribe a new drug called aetohydroamic acid (AHA). AHA is used along with long-term antibiotic drugs to prevent the infection that leads to stone growth.
To prevent calcium stones that form in hyperparathyroid patients, a surgeon may remove all of the parathyroid glands (located in the neck). This is usually the treatment for hyperparathyroidism as well. In most cases, only one of the glands is enlarged. Removing the gland ends the patient's problem with kidney stones.
Surgical Treatment
Some type of surgery may be needed to remove a kidney stone if the stone:
· does not pass after a reasonable period of time and causes constant pain
· is too large to pass on its own
· blocks the urine flow
· causes ongoing urinary tract infection
· damages the kidney tissue or causes constant bleeding, or
· has grown larger (as seen on follow up x-ray studies).
Until recently, surgery to remove a stone was very painful and required a lengthy recovery time (4 to 6 weeks). Today, treatment for these stones is greatly improved. Many options exist that do not require major surgery.
Extracorporeal Shockwave Lithotripsy.
Extracorporeal shockwave lithotripsy (ESWL) is the most frequently used surgical procedure for the treatment of kidney stones. ESWL uses shockwaves that are created outside of the body to travel through the skin and body tissues until the waves hit the dense stones. The stones become sand-like and are easily passed through the urinary tract in the urine.
There are several types of ESWL devices. One device positions the patient in the water bath while the shock waves are transmitted. Other devices have a soft cushion or membrane on which the patient lies. Most devices use either x-rays or ultrasound to help the surgeon pinpoint the stone during treatment. For most types of ESWL procedures, some type of anesthesia is needed.
In some cases, ESWL may be done on an outpatient basis. Recovery time is short, and most people can resume normal activities in a few days.
Complications may occur with ESWL. Most patients have blood in the urine for a few days after treatment. Bruising and minor discomfort on the back or abdomen due to the shockwaves are also common. To reduce the chances of complications, doctors usually tell patients to avoid taking aspirin and other drugs that affect blood clotting for several weeks before treatment.
In addition, the shattered stone fragments may cause discomfort as they pass through the urinary tract in the urine. In some cases, the doctor will insert a small tube called a stent through the bladder into the ureter to help the fragments pass. Sometimes the stone is not completely shattered with one treatment and additional treatments may be required.
Percutaneous Nephrolithotomy.
Sometimes a procedure called percutaneous nephrolithotomy is recommended to remove a stone. This treatment is often used when the stone is quite large or in a location that does not allow effective use of EWSL.
In this procedure, the surgeon makes a tiny incision in the back and creates a tunnel directly into the kidney. Using an instrument called a nephroscope, the stone is located and removed. For large stones, some type of energy probe (ultrasonic or electrohydraulic) may be needed to break the stone into small pieces. Generally, patients stay in the hospital for several days and may have a small tube called a nephrostomy tube left in the kidney during the healing process.
One advantage of percutaneous nephrokithotomy over ESWL is that the surgeon removes the stone fragments instead of relying on their natural passage from the kidney.
Ureteroscopic Stone Removal.
Although some ureteral stones can be treated with ESWL, urethroscopy may be needed for mid- and lower-ureter stones. No incision is made in this procedure. Instead, the surgeon passes a small fiberoptic instrument called a ureteroscope through the urethra and bladder into the ureter. The surgeon then locates the stone and either removes it with a cage-like device or shatters it with a special instrument that produces a form of shockwave. A small tube or stent may be left in the ureter for a few days after treatment to help the lining of the ureter heal.
Is There Any Current Research on Kidney Stones?
The Division of Kidney, Urologic, and Hematologic Diseases of the National Institutes of Diabetes and Digestive and Kidney Diseases (NIDDK) funds research on the causes, treatments, and prevention of kidney stones. The NIDDK is part of the Federal Government's National Institutes of Health in Bethesda, Maryland.
New drugs and the growing field of lithotripsy have greatly improved the treatment of kidney stones. Still, NIDDK researchers and grantees seek to answer questions such as:
· Why do some people continue to have painful stones?
· How can doctors predict, or screen, who is as risk for getting stones?
· What are the long-term effects of lithotripsy?
· Do genes play a role in stone formation?
· What is the natural substance(s) found in urine that blocks stone formation?
Researchers are also working to develop new drugs with fewer side effects.
Prevention Points to Remember
People who have a family history of stones or who have had more than one stone are likely to develop another. A good first step to prevent any type of stone is to drink plenty of liquids--water is best. If a person is at risk for developing stones, the doctor may perform certain blood and urine tests. These tests will determine which factors can be best altered to reduce that risk. Some patients will need medicines to prevent stones from forming. People with chronic urinary tract infections and stones will often need the stone removed if the doctor determines that the infection results from the stone's presence. Patients must receive careful followup to be sure that the infection has cleared.
Foods and Drinks Containing Caalcium and Oxalate
Persons prone to forming calcium oxalate stones may be asked by their doctor to cut back on certain foods on this list.
| apples asparagus beer beets berries, various (e.g., cranberries, strawberries) black pepper broccoli cheese chocolate cocoa coffee cola drinks collards figs
| grapes ice cream milk oranges parsley peanut butter pineapples spinach Swiss chard rhubarb tea turnips vitamin C yogurt
| Persons should not give up or avoid eating these types of foods without talking to their doctor first. In most cases, these foods can be eaten in limited amounts.
The National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC) is a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The NIDDK is part of the National Institutes of Health under the U.S. Public Health Service. Established in 1987, the clearinghouse provides information about diseases of the kidneys and urologic system to people with kidney and urologic disorders and to their families, health care professionals, and the public. NKUDIC answers inquiries; develops, reviews, and distributes publications; and works closely with professional and patient organizations and Government agencies to coordinate resources about kidney and urologic diseases.
Publications produced by the clearinghouse are carefully reviewed for scientific accuracy, content, and readability.
| Lyme Disease, The Facts, The Challenge
Introduction
In the early 1970s, a mysterious clustering of arthritis occurred among children in Lyme, Connecticut, and surrounding towns. Medical researchers soon recognized the illness as a distinct disease, which they called Lyme disease. They subsequently described the clinical features of Lyme disease, established the usefulness of antibiotic therapy in its treatment, identified the deer tick as the key to its spread, and isolated the bacterium that caused it.
Lyme disease is still mistaken for other ailments, and it continues to pose many other challenges: it can be difficult to diagnose because of the inadequacies of today's laboratory tests; it can be troublesome to treat in its later phases; and its prevention through the development of an effective vaccine is hampered by the elusive nature of the bacterium.
The National Institutes of Health (NIH), a part of the U.S. Public Health Service, conducts and supports biomedical research aimed at meeting the challenges of Lyme disease. This brochure presents the most recently available information on the diagnosis, treatment, and prevention of Lyme disease.
How Lyme Disease Became Known
Lyme disease was first recognized in 1975 after researchers investigated why unusually large numbers of children were being diagnosed with juvenile rheumatoid arthritis in Lyme and two neighboring towns. The investigators discovered that most of the affected children lived near wooded areas likely to harbor ticks. They also found that the children's first symptoms typically started in the summer months coinciding with the height of the tick season. Several of the patients interviewed reported having a skin rash just before developing their arthritis, and many also recalled being bitten by a tick at the rash site.
Further investigations resulted in the discovery that tiny deer ticks infected with a spiral-shaped bacterium or spirochete (which was later named Borrelia burgdorferi) were responsible for the outbreak of arthritis in Lyme.
Ticks that Most Commonly Transmit B. burgdorferi in the U.S. (These ticks are all quite similar in appearance.)
Ixodes dammini--most common in the northeast and midwest
Ixodes scapularis--found in south and southeast
Ixodes pacificus--found on the west coast
In Europe, a skin rash similar to that of Lyme disease had been described in medical literature dating back to the turn of the century. Lyme disease may have spread from Europe to the United States in the early 1900s but only recently became common enough to be detected.
The ticks most commonly infected with B. burgdorferi usually feed and mate on deer during part of their life cycle. The recent resurgence of the deer population in the northeast and the influx of suburban developments into rural areas where deer ticks are commonly found have probably contributed to the disease's rising prevalence.
The number of reported cases of Lyme disease, as well as the number of geographic areas in which it is found, has been increasing. Lyme disease has been reported in nearly all states in this country, although most cases are concentrated in the coastal northeast, mid-Atlantic states, Wisconsin and Minnesota, and northern California. Lyme disease is endemic in large areas of Asia and Europe. Recent reports suggest that it is present in South America, too.
Symptoms of Lyme Disease
Erythema Migrans. In most people, the first symptom of Lyme disease is a red rash known as erythema migrans (EM). The telltale rash 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 within a few weeks of a tick bite and usually occurs 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. Although these flu-like symptoms may resemble those of common viral infections, Lyme disease symptoms tend to persist or may occur intermittently.
Arthritis. After several months of being infected by B. burgdorferi, slightly more than half 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. About 10 to 20 percent of untreated patients will go on to develop chronic arthritis.
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 motor 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.
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.
Heart Problems. Fewer than one out of ten Lyme disease patients develops heart problems, such as an irregular heartbeat, which can be signalled by dizziness or shortness of breath. These symptoms rarely last more than a few days or weeks. Such heart abnormalities generally surface several weeks after infection.
Other Symptoms. Less commonly, Lyme disease can result in eye inflammation, hepatitis, and severe fatigue, although none of these problems is likely to appear without other Lyme disease symptoms being present.
How Lyme Disease Is Diagnosed
Lyme disease may be difficult to diagnose because many of its symptoms mimic those of other disorders. In addition, the only distinctive hallmark unique to Lyme disease--the erythema migrans rash--is absent in at least one-fourth of the people who become infected. Although a tick bite is an important clue for diagnosis, many patients cannot recall having been bitten recently by a tick. This is not surprising because the tick is tiny, and a tick bite is usually painless.
When a patient with possible Lyme disease symptoms does not develop the distinctive rash, a physician will rely on a detailed medical history and a careful physical examination for essential clues to diagnosis, with laboratory tests playing a supportive role.
Most Common Symptoms of Lyme Disease (One or more may be present at different times during infection)
Early Infection
* Rash (erythema migrans) * Muscle and joint aches * Headache * Stiff neck * Significant fatigue * Fever * Facial paralysis (Bell's palsy) * Meningitis * Brief episodes of joint pain and swelling
Less common:
* Eye problems such as conjunctivitis * Heart abnormalities such as heart block and myocarditis
Late Infection
* Arthritis, intermittent or chronic
Less Common:
* Neurological conditions such as encephalitis or confusion * Skin disorders
Blood Tests. Unfortunately, the Lyme disease microbe itself is difficult to isolate or culture from body tissues or fluids. Most physicians look for evidence of antibodies against B. burgdorferi in the blood to confirm the bacterium's role as the cause of a patient's symptoms. Antibodies are molecules or small substances tailor-made by the immune system to lock onto and destroy specific microbial invaders.
Some patients experiencing nervous system symptoms may also undergo a spinal tap. Through this procedure doctors can detect brain and spinal cord inflammation and can look for antibodies in the spinal fluid.
The inadequacies of the currently available antibody tests may prevent them from firmly establishing whether the Lyme disease bacterium is causing a patient's symptoms. In the first few weeks following infection, antibody tests are not reliable because a patient's immune system has not produced enough antibodies to be detected. Antibiotics given to a patient early during infection may also prevent antibodies from reaching detectable levels, even though the Lyme disease bacterium is the cause of the patient's symptoms.
Because some tests cannot distinguish Lyme disease antibodies from antibodies to similar organisms, patients may test positive for Lyme disease when their symptoms actually stem from other bacterial infections. A lack of standardization of antibody tests and poor quality control also contribute to inaccuracies in test results.
Due to these pitfalls, physicians must rely on their clinical judgement in diagnosing someone with Lyme disease even though the patient does not have the distinctive erythema migrans rash. Such a diagnosis would be based on the history of a tick bite, the patient's symptoms, a thorough ruling out of other diseases that might cause those symptoms, and other implicating evidence. This evidence could include such factors as an initial appearance of symptoms during the summer months when tick bites are most likely to occur, outdoor exposure in an area where Lyme disease is common, and a clustering of Lyme disease symptoms among family members.
New Tests Under Development. To improve the accuracy of Lyme disease diagnosis, NIH-supported researchers are developing a number of new tests that promise to be more reliable than currently available procedures. Some of these detect distinctive protein fragments of the Lyme disease bacterium in fluid samples.
NIH scientists are developing tests that use the highly sensitive genetic engineering technique, known as polymerase chain reaction (PCR), to detect extremely small quantities of the genetic material of the Lyme disease bacterium in body tissues and fluids.
Several new methods to detect infection are under development in NIH laboratories. Scientists have isolated a protein of B. burgdorferi, called p39, that reacts strongly on blood tests. The presence of antibodies to this protein was found to be a strong indicator of the presence of B. burgdorferi. Although further research will be needed to determine how soon after infection it can detect the bacterium, p39 may prove to be an ideal test for Lyme disease.
A somewhat different approach is the use of an assay based on two closely related spirochetal proteins that are not found in other species of bacterial spirochetes. This assay differs from blood tests now in use because it detects products of the spirochete itself rather than detecting human antibodies to the bacterium.
How Lyme Disease Is Treated
Nearly all Lyme disease patients can be effectively treated with an appropriate course of antibiotic therapy. In general, the sooner such therapy is begun following infection, the quicker and more complete the recovery.
Antibiotics, such as doxycycline or amoxicillin taken orally for a few weeks, can speed the healing of the erythema migrans rash and usually prevent subsequent symptoms such as arthritis or neurological problems.
Patients younger than 9 years or pregnant or lactating women with Lyme disease are treated with amoxicillin or penicillin because doxycycline can stain the permanent teeth developing in young children or unborn babies. Patients allergic to penicillin are given erythromycin.
Lyme disease patients with neurological symptoms are usually treated with the antibiotic ceftriaxone given intravenously once a day for a month or less. Most patients experience full recovery.
Lyme arthritis may be treated with oral antibiotics. Patients with severe arthritis may be treated with ceftriaxone or penicillin given intravenously. To ease these patients' discomfort and further their healing, the physician might also give anti-inflammatory drugs, draw fluid from affected joints, or surgically remove the inflamed lining of the joints.
Lyme arthritis resolves in most patients within a few weeks or months following antibiotic therapy, although it can take years to disappear completely in some people. Some Lyme disease patients who are untreated for several years may be cured of their arthritis with the proper antibiotic regimen. If the disease has persisted long enough, however, it may irreversibly damage the structure of the joints.
Physicians prefer to treat Lyme disease patients experiencing heart symptoms with antibiotics such as ceftriaxone or penicillin given intravenously for about 2 weeks. If these symptoms persist or are severe enough, patients may also be treated with corticosteroids or given a temporary internal cardiac pacemaker. People with Lyme disease rarely experience long-term heart damage.
Following treatment for Lyme disease, some people still have persistent fatigue and achiness. This general malaise can take months to subside, although it generally does so spontaneously without requiring additional antibiotic therapy.
Researchers are currently conducting studies to assess the optimal duration of antibiotic therapy for the various manifestations of Lyme disease. Investigators are also testing newly developed antibiotics for their effectiveness in countering the Lyme disease bacterium.
Unfortunately, a bout with Lyme disease is no guarantee that the illness will be prevented in the future. The disease can strike more than once in the same individual if he or she is reinfected with the Lyme disease bacterium.
Lyme Disease Prevention
Avoidance of Ticks. At present, the best way to avoid Lyme disease is to avoid 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 summer, when immature ticks are most prevalent. 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. Because the adult ticks feed on deer, areas where deer are frequently seen are likely to harbor sizable numbers of deer ticks.
To help prevent tick bites, people entering tick-infested areas should walk in the center of trails to avoid picking up ticks from overhanging grass and brush.
To minimize skin exposure to both ticks and insect repellents, people outdoors in tick-infested areas should wear long pants and long-sleeved shirts that fit tightly at the ankles and wrists. As a further safeguard, people should wear a hat, tuck pant legs into socks, and wear shoes that leave no part of the feet exposed. To make it easy to detect ticks, people should wear light-colored clothing.
To repel ticks, people can spray their clothing with the insecticide permethrin, which is commonly found in lawn and garden stores. Insect repellents that contain a chemical called DEET (N,N-diethyl-M-toluamide) can also be applied to clothing or directly onto skin. 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 to DEET.
Pregnant women should be especially careful to avoid ticks in Lyme disease areas because the infection can be transferred to the unborn child. Such a prenatal infection can make the woman more likely to miscarry or deliver a stillborn baby.
Checking for Ticks. Once indoors, people should check themselves and their children for ticks, particularly in the hairy regions of the body. The immature deer ticks that are most likely to cause Lyme disease are only about the size of a poppy seed, so they are easily mistaken for a freckle or a speck of dirt. All clothing should be washed. Pets should be checked for ticks before entering the house, because they, too, can develop symptoms of Lyme disease. In addition, a pet can carry ticks into the house. These ticks could fall off without biting the animal and subsequently attach to and bite people inside the house.
If a tick is discovered attached to the skin, it should be pulled out gently with tweezers, taking care not to squeeze the tick's body. An antiseptic should then be applied to the bite. Studies by NIH-supported researchers suggest that a tick must be attached for many hours to transmit the Lyme disease bacterium, so prompt tick removal could prevent the disease.
The risk of developing Lyme disease from a tick bite is small, even in heavily infested areas, and most physicians prefer not to treat patients bitten by ticks with antibiotics unless they develop symptoms of Lyme disease.
Vaccine Development. Because Lyme disease is difficult to diagnose and sometimes does not respond to treatment, researchers are trying to create a vaccine that will protect people from the disorder. Vaccines work in part by prompting the body to generate antibodies. These custom-shaped molecules lock onto specific proteins made by a virus or bacterium--often those proteins lodged in the microbe's outer coat. Once antibodies attach to an invading microbe, other immune defenses are evoked to destroy it.
Tips for Personal Protection
* Avoid tick-infested areas, especially in May, June, and July.*
* Wear light-colored clothing so that ticks can be easily spotted.
* Wear long-sleeved shirts and closed shoes and socks.
* Tuck pant legs into socks or boots and tuck shirt into pants
* Apply insect repellant containing permethrin to pants, socks, and shoes, and compounds containing DEET on exposed skin. Do not overuse these products.
* Walk in the center of trails to avoid overgrown grass and brush.
* After being outdoors in a tick-infested area, remove, wash, and dry clothing.
* Inspect the body thoroughly and remove carefully any attached ticks.
* Check pets for ticks.
* Local health departments and park or agricultural extension services may have information on the seasonal and geographical distribution of ticks in your area.
How to Remove a Tick
* Tug gently but firmly with blunt tweezers near the "head" of the tick until it releases its hold on the skin.
* To lessen the chance of contact with the bacterium, try not to crush the tick's body or handle the tick with bare fingers.
* Swab the bite area thoroughly with an antiseptic to prevent bacterial infection.
Development of an effective vaccine for Lyme disease has been difficult to create for a number of reasons. Scientists need to find out how the immune system protects against the bacterium because people who have been infected once can acquire the infection again. In addition, there are several different strains of the bacterium, each with its own distinct set of proteins, and bacteria within an individual strain may change the shape of their proteins over time so that antibodies can no longer identify and lock onto them.
Tick Eradication. In the meantime, researchers are trying to develop an effective strategy for ridding areas of deer ticks. Studies show that a single fall spraying of pesticide in wooded areas can substantially reduce the number of adult deer ticks residing there for as long as a year. Spraying on a large scale, however, may not be economically feasible and may prompt environmental or health concerns.
Scientists are also pursuing biological control of deer ticks by introducing tiny stingerless wasps, which feed on immature ticks, into tick-infested areas. Researchers are currently assessing the effectiveness of this technique.
Successful control of deer ticks will probably depend on a combination of tactics. More studies are needed before wide-scale tick control strategies can be implemented.
Research-The Key to Progress
Although Lyme disease poses many challenges, they are challenges the medical research community is well equipped to meet. New information on Lyme disease is accumulating at a rapid pace, thanks to the scientific research being conducted around the world.
This brochure is not copyrighted and users are encouraged to reproduce and distribute as many free copies as needed. Single copies and black-and-white reproducible artwork are available by writing to: Lyme Disease Booklet, NIAMS/NIH, Box AMS, 9000 Rockville Pike, Bethesda, Maryland 20892.
For more information about Lyme disease, you may want to contact your State or local Department of Health (check the government listings in your phone book). This agency may be able to tell you whether Lyme disease is common in your area. Also, staff of the Department may suggest nearby hospitals or clinics where you can be tested for Lyme disease. They may also know local places where ticks can be tested for the bacterium.
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