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Lifespan’s A - Z Health Information Library |
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Lyme disease and related tick-borne infectionsHighlightsCauses Lyme disease is caused by the bacterium Borrelia (B.) burgdorferi, which is transmitted through the bite of a deer tick. Either nymph or adult ticks can transmit B. Burgdorferi. Risk Factors
Prevention
Symptoms
Treatment Most cases of Lyme disease can be prevented or cured with prompt antibiotic treatment following a deer tick bite. If a preventive antibiotic is needed, a single dose of doxycycline may suffice. To treat active disease, antibiotics are usually given for 2 - 4 weeks. Current guidelines do not recommend long-term antibiotic treatment for any stage or complication of Lyme disease. IntroductionLyme disease is the most commonly reported vector-borne disease in the United States. Vector-borne infections are transmitted by insects. Borrelia BurgdorferiThe Lyme disease infection in the U.S. is caused by a spirochete called Borrelia (B.) burgdorferi. A spirochete is a bacteria-like organism with a cylinder-like shape surrounded by an outer membrane. Lyme researchers have completed the DNA encoding of B. burgdorferi. Researchers learned that certain proteins coat its outer surface. These proteins, collectively called Osp, are responsible for attaching the spirochete to cells in humans and other mammals. Ixodes TicksThe vector that carries B. burgdorferi in the U.S. Northeast and North Central states is the Ixodes scapularis tick. The Ixodes scapularis tick goes through three stages over the course of about 2 years:
The Cycle of InfectionCycle of Infection in the Northeast and North Central U.S. For Lyme disease to exist in these regions, three factors must come into close contact:
The following describes the most common cycle in the Northeast and North Central U.S. by which the Lyme disease infection eventually reaches a person:
Cycle of Infection in the Northwest. In the Northwest, the infecting insect is the Western blacklegged tick, Ixodes pacificus. Here, the frequency of Lyme disease is much lower than in the other two regions because the animal carrier of the infection is the dusky-footed wood rat. This animal is bitten and infected by the Ixodes neotomae tick, which does not bite humans. The actual tick that spreads B. burgdorferi to people is Ixodes pacificus, which must feed first on an already infected wood rat. Other Infections Carried by the Ixodes TickThe two other important infections carried by the Ixodes scapularis tick are human granulocytic anaplasmosis (HGA) and babesiosis. Although they are both borne by the same tick as Lyme disease, all three of these infections are entirely different diseases. Risk for Coinfection. Because the same tick can carry Lyme disease, HGA, and babesiosis, there is some risk for co-infection with two or more of these organisms. The risk, however, is not wholly known. Studies have reported that 2 - 25% of ticks in several high-tick locations carry both HGA and Lyme. In one study of patients located in high-risk areas in New England, 39% had more than one of these infections transmitted by the Ixodes tick. There is no evidence that co-infection with one or more of these infections causes a more severe condition than either infection separately. SymptomsSymptoms of Lyme disease are diverse and often occur in early and late phases. They vary widely from person to person. Any one symptom may fail to appear, and symptoms may overlap in various combinations. Death from Lyme disease is very rare and occurs only in a few cases in which the heart is severely affected. Typical Course
Skin RashThe bull's-eye skin rash, known as erythema chronicum migrans (ECM), usually first appears on the thigh, buttock, or trunk in older children and adults, and on the head or neck in young children. The bull's eye rash, which is commonly believed to be the classic sign of Lyme disease, may take the following course:
Up to 20% of people infected with Lyme disease do not exhibit the rash. In most patients, any rash fades completely after 3 - 4 weeks, although secondary rashes may appear during the later stages of disease. Flu-like SymptomsA flu-like condition is the most common sign of Lyme infection, and it can occur with or without a rash. Symptoms can last from 5 - 21 days and may include:
Joint PainJoint pain can arise at the same time as the skin rash. In early stages of Lyme disease, patients may experience migratory pain in joints, muscles, and tendons. In the later stages of the disease, arthritis may develop in one or two large joints such as the knee, elbow, or shoulder. (Knees are usually affected most.) About 10% of patients with untreated Lyme disease develop chronic arthritis that can erode bone and cartilage. Neurologic SymptomsAbout 15% of untreated patients develop neurologic symptoms. They can occur in all stages of the disease and can affect any part of the nervous system. Common Early Neurologic Symptoms. Most often, neurologic symptoms first appear while the initial skin rash is still present or within 6 weeks after its disappearance. Sometimes they are the first symptoms that the patient experiences. The most common neurologic symptoms may be headaches, sleep problems, and mood disturbance. Memory problems can also occur. Neurologic symptoms typically improve or resolve within a few weeks or months, even in untreated patients. Bell's Palsy. In 5 - 10% of untreated Lyme patients, the facial nerve is affected, which results in Bell's palsy. This is a sudden weakness and drooping of the facial muscles and eyelid on one side of the face. Nerves around the facial area may also cause numbness, dizziness, double vision, and hearing changes. Another common neurologic problem is pain in the lower spine. It resembles low back pain from arthritis (although in the case of Lyme disease the skin near the spine may have abnormal sensations). Of note, Lyme disease has been observed in more than half the children who develop Bell's palsy. Symptoms of Meningitis. In about 10 - 15% of patients, the infection takes place in the membranes that surround the brain and spinal cord (called meningitis). This can cause:
Symptoms of Lyme Encephalopathy. In some cases of untreated disease, the infection causes a condition called Lyme encephalopathy or neuroborreliosis. This causes the following symptoms:
Other Neurologic Symptoms.
Other SymptomsHeart symptoms, such as an irregular heartbeat, may develop several weeks after infection, but this is not very common. In rare cases, Lyme disease may cause eye inflammation (conjunctivitis). Risk FactorsSince 1991, when Lyme disease became a reportable disease, annual cases have doubled. (This increase is probably both due to increased infection rates as well as better diagnosis.) In general, about 25,000 cases of Lyme disease are now reported in the U.S. each year. General Risk FactorsAnyone exposed to ticks is at risk for Lyme disease and other tick-borne diseases. Pets are also at risk. Naturally, anyone who is regularly outside in areas where tick rates are high has a greater than average risk for becoming infected. Age. The highest reported incidence of Lyme disease occurs among children 5 - 14 years old and adults 45 - 54 years old. Sex. Men and women are equally at risk. The Risk for Lyme Disease after a Tick BiteIn general, the risk for developing Lyme disease after a tick bite is only 1 - 3%. The risk varies depending on different factors:
Geographic LocationsLocations in the U.S. Lyme disease has been reported in nearly all U.S. states. However, most Lyme disease cases are concentrated in the northeastern, mid-Atlantic, and north central states. Although Lyme disease was named for a town in Connecticut where the first American cases of the disease were described, in recent years Massachusetts, New Jersey, and Pennsylvania have reported the greatest number of cases. Worldwide Locations. Pockets of Lyme disease exist around the world. The disease is common in Europe, particularly in forested areas of middle Europe and Scandinavia. The Borrelia family is also responsible for tick infections in Europe, but different subspecies (B. garinii and B. afzelii) may be more common there and cause slightly different symptoms. The infection has also been reported in Russia, China, and Japan. High-Risk LandscapesDeer ticks thrive in grassy areas that have low sunlight and high humidity. Woodlands and fields are prime habitats, but these ticks can also be found in the long grasses adjacent to beaches. The ticks are not confined to rural settings. In suburban areas, they can live in overgrown lawns, groundcover plants, and leaf litter. Time of YearThe exact time of year for risk depends on a geographic region's seasons and how they affect the tick's breeding cycle. In general, the highest risk for Lyme disease onset is from June through August, and the lowest risk is from December through March. ComplicationsPrompt treatment with antibiotics is very effective in curing Lyme disease in nearly all infected people, including children. However, untreated Lyme disease can lead to complications. Complications of Late-Stage Lyme DiseasePeople at highest risk for persistent symptoms are those who go the longest before treatment. Fortunately, public vigilance has significantly reduced the rates of late-stage Lyme disease. Antibiotics given at late stages will relieve symptoms in most people, although about 5% may continue to have problems. Left untreated, Lyme disease can spread (disseminate). The infection may affect almost any part of the body and cause the following complications:
About 60% of untreated patients develop arthritis, which usually affects a knee or other large joint. About 10 - 20% of patients develop neurological or heart problems. Persistent neurological symptoms include headache, attention and memory problems, and depression. Patients may also experience pain or tingling in legs or arms (peripheral neuropathy), numbness, or facial paralysis (Bell’s palsy). Neurologic symptoms generally resolve and improve within a year. The main heart complications are electrical conduction problems caused by the infection, which can result in an abnormally slow heart rate. Infections in the Pregnant Patient. The occurrence of any infection during pregnancy is of special concern. While the current research indicates that complications during pregnancy due to Lyme disease are very rare, pregnant women should still adhere scrupulously to preventive measures.
Post-Lyme Disease SyndromeLyme disease is a curable condition. Nearly all patients (95%) improve after a short course of antibiotics. In very rare cases, patients continue to complain of persistent non-specific symptoms, such as fatigue, muscle aches, cognitive problems, and headache lasting years after completing antibiotic treatment for the initial infection. This syndrome, which resembles chronic fatigue syndrome (CFS) or fibromyalgia, is referred to as post-Lyme disease syndrome. In the past, it has been called “chronic Lyme disease.” However, based on many reviews of scientific literature, researchers and doctors strongly believe that Lyme disease does not have a chronic state. According to the 2006 guidelines from the Infectious Diseases Association of America, post-Lyme disease syndrome is the preferred name for this condition. Patients are considered to have this syndrome if they still have symptoms 6 months after treatment. Most important, there must be definitive evidence that the patient was originally infected by the B. burgdorferi spirochete. If there is no documented evidence of infection, it could be that the patient never had Lyme disease, or may be experiencing a new or different type of illness. If the patient did have Lyme disease, symptoms should eventually resolve without additional antibiotic treatments. Doctors strongly advise against prolonged antibiotic treatment. There is no evidence that long-term antibiotics help treat post-Lyme disease syndrome symptoms. In addition, long-term antibiotic treatment carries its own serious risks, such as the development of antibiotic-resistant superbugs. Diseases with Similar SymptomsMany other illnesses can mimic various features of Lyme disease. Depending on the symptoms, a doctor may be able to perform the evaluations necessary to rule out other conditions. Ruling Out Other Tick-Borne or Spirochete InfectionsOther infections can produce fever, headache, muscle aches, fatigue, and some of the neurologic or cardiac features of early Lyme disease. Some are transmitted by the same tick as Lyme disease. Co-Infections Transmitted by the Ixodes Tick. Babesiosis and human granulocytic anaplasmosis (HGA) are transmitted by the same tick that carries Lyme disease. People may be co-infected with one or more of these infections, all of which can cause flu-like symptoms. If these symptoms persist and there is no rash, it is less likely that Lyme disease is present. Still, diagnosing a co-infection is difficult. Other Spirochete Infections. Leptospirosis is a spirochete infection spread through animals or contaminated water that most often affects young people during the summer or fall. Other Tick-Borne Infections. A number of other tick-borne diseases may resemble Lyme disease, although they are more common in parts of the U.S. where Lyme disease is less prevalent.
Allergic Reaction to the Tick. If a rash, even ring-shaped, appears hours rather than days after a tick bite, it is most likely an allergic reaction to the tick, not a symptom of Lyme disease. Other Insect Bites. Not every rash seen in regions where Lyme disease is common is caused by a tick. The bites of many insects and spiders can cause a skin reaction. Autoimmune DiseasesA number of autoimmune diseases have chronic and low-level symptoms that may be confused with Lyme disease.
Diseases Resembling Post-Lyme Disease SyndromeA number of conditions cause chronic fatigue and joint and muscle aches that resemble descriptions of post-Lyme disease syndrome:
MeningitisThe early neurologic symptoms of Lyme disease (headache, stiff neck, and fatigue) can easily be mistaken for viral meningitis. Children with viral meningitis are more likely to have a higher fever. Patients with Lyme disease often have other symptoms, such as the bull's-eye rash. DiagnosisProper diagnosis of Lyme disease is important. A diagnosis of Lyme disease is straightforward if the patient meets the following criteria:
If the patient meets all the criteria, except the rash, the doctor may undertake the enzyme-linked immunosorbent assay (ELISA) or the Western Blot test. CultureIn a few cases, if the patient seeks a diagnosis within the first 2 - 3 weeks, the doctor may take a sample of the skin or of the blood. If Lyme spirochete is present, it may be identified in the laboratory in a culture medium (a substance in which the organism can thrive and reproduce). This is necessary only if a doctor suspects Lyme but the diagnosis is not clear. Immune TestingIf the infection is not obvious from the patient's history and physical symptoms, but Lyme disease is suspected, the doctor may run tests for evidence of specific factors that suggest infection with B. burgdorferi. Such factors include:
Specific Tests. The U.S. Centers for Disease Control (CDC) recommends a two-step process for Lyme disease blood tests:
The CDC recommends only these tests. Other tests -- such as urine antigen, immunofluroescent staining, and lymphocyte transformation -- do not have enough scientific evidence to support their use. Accuracy of the Tests. These tests are very expensive, and none are completely accurate in either identifying Lyme or ruling it out. They should never be used to make a primary diagnosis of Lyme disease in patients who do not have obvious symptoms of the disease. Both false positive and false negative results are common with these tests. False positive results occur when the test suggests the presence of the disease, but the person does not actually have an active infection. This may occur in different ways:
False negative results miss the actual presence of the disease. These results are also common. (If the results are negative but Lyme disease is highly suspected, the doctor will probably prescribe antibiotics anyway.) False negative results occur for a number of reasons:
All of this means that a negative blood test does not rule out a diagnosis of Lyme disease, particularly if symptoms strongly suggest its presence. Conversely, a positive blood test does not prove that Lyme disease is causing the symptoms. A second blood test, taken several weeks later, may help. Polymerase Chain Reaction (PCR) TestThe polymerase chain reaction (PCR) test detects the DNA of the bacteria that causes Lyme disease. However, it requires technical expertise and expensive equipment, and can be performed only in a few laboratories in the country. The test also has a high risk of false-positive results. Research indicates that blood or urine samples do not provide accurate results, but skin biopsies may be useful in some cases. At this point, the PCR test is reserved for certain patients with specific diagnostic problems. For most patients, standard antibody tests are preferred. Tests for Neurologic InvolvementAnalysis of Spinal Fluid. In patients who have neurologic symptoms, a lumbar puncture (a spinal tap) may be used to test for the bacteria in spinal fluid and may be useful for an early diagnosis of Lyme disease. TreatmentAntibiotics are the drugs of choice for all phases of Lyme disease. In nearly all cases they can cure Lyme, even in later stages. Preventive Antibiotics after a Tick BiteAccording to guidelines from the Infectious Diseases Society of America (IDSA), people bitten by deer ticks should not routinely receive antibiotics to prevent the disease. A single dose of the antibiotic doxycycline may be given in situations that meet all of the following conditions:
In general, the risk of developing Lyme disease after being bitten by a tick is only 1 - 3%. However, patients who have removed attached ticks from themselves should inform their doctors. Patients who have been bitten by a tick should be monitored for up to 30 days to make sure they do not develop symptoms of Lyme disease, especially the tell-tale bull’s-eye rash. If you do develop a skin lesion or flu-like illness during this time, be sure to tell your doctor. Treating Early Stage Lyme DiseaseThe early stages of Lyme disease usually involve classic bull’s-eye rash (erythema migrans) and flu-like symptoms of chills and fever, fatigue, muscle pain, and headache. In rare cases, patients develop an abnormal heartbeat (Lyme carditis). All of these conditions are treated with 10 - 28 days of antibiotics. The exact number of days depends on the drug used, and the patient’s response to it. Antibiotics for treating Lyme disease generally include:
Side Effects of Antibiotics. The most common side effects of nearly all antibiotics are gastrointestinal problems, including cramps, nausea, vomiting, and diarrhea. Allergic reactions can also occur with all antibiotics, but are most common with medications derived from penicillin or sulfa. These reactions can range from mild skin rashes to rare but severe, even life-threatening, anaphylactic shock. Some drugs, including certain over-the-counter medications, interact with antibiotics. Patients should report to their doctors all medications they are taking. Treating Late Stage Lyme DiseaseMost cases of Lyme disease involve a rash and flu-like symptoms that resolve within 1 month of antibiotic treatment. However, some patients go on to develop late-stage Lyme disease, which includes Lyme arthritis and neurologic Lyme disease. Slightly more than half of patients infected with B. burgdorferi develop Lyme arthritis. About 10 - 20 % of patients develop neurologic Lyme disease. A very small percentage of patients may develop acrodermatitis chronica atrophicans, a serious type of skin inflammation. These conditions are treated for up to 28 days with antibiotic therapy. If arthritis symptoms persist for several months, a second 2 - 4 week course of antibiotics may be recommended. Oral antibiotics (doxycycline, amoxicillin, or cefuroxime) are used for Lyme arthritis and acrodermatitis chronica atrophicans. (In rare cases, patients with arthritis may need intravenous antibiotics.) A 2 - 4 week course of intravenous ceftriaxone is used for treating severe cases of neurological Lyme disease. For milder cases, 2 - 4 weeks of oral doxycycline is an effective option. Treating Post-Lyme Disease SyndromeIn about 5% of cases, symptoms persist after treatment, a condition referred to as post-Lyme disease syndrome. The treatment of post-Lyme disease syndrome is a controversial issue. Most doctors do not recommend continuing antibiotic therapy beyond 30 days. Scientific studies do not show any evidence that the benefits of long-term antibiotic treatment outweigh its risks. Long-term antibiotic treatment can lead to a serious and difficult-to-treat infection called Clostridiumdifficile, and can also cause the patient to become allergic to the antibiotic. Experimental and alternative remedies are also not recommended. However, some patients may benefit from learning pain control and cognitive behavioral techniques to help them cope with and manage their symptoms. Herbs and SupplementsSome people use vitamin B complex, omega-3 and omega-6 fatty acids (found in primrose oil and fish oils), and magnesium supplements (magnesium L-lactate dihydrate) to help relieve symptoms. No evidence suggests that they are beneficial. Any such therapies should be discussed with a doctor. Newsletters and Internet sites have cropped up in recent years advertising untested treatments to patients with symptoms of Lyme disease who are frustrated with traditional medical channels. Some remedies are dangerous, and most are ineffective. The Food and Drug Administration (FDA) has warned people not to use an alternative medicine product called bismacine (also known as chromacine). This injectable product contains high amounts of bismuth, a heavy metal that can be poisonous. People who have taken bismacine have experienced heart and kidney failure, and one death has been reported. Although some people claim that bismacine can help treat Lyme disease, it is not approved for the treatment of any illness or condition. Generally, manufacturers of herbal remedies and dietary supplements do not need FDA approval to sell their products. Just like a drug, herbs and supplements can affect the body's chemistry, and therefore have the potential to produce side effects that may be harmful. There have been a number of reported cases of serious and even lethal side effects from herbal products. Always check with your doctor before using any herbal remedies or dietary supplements. PreventionEveryone should avoid specific tick-infested areas, including tall grass, woods, and bushes where ticks tend to congregate. If this is not possible, people should take additional preventive measures. The U.S. Centers for Disease Control (CDC) also recommends:
Protecting Property from Tick InfestationMowing the grass regularly, clearing away leaves, and placing wood chips as a barrier around a lawn can help greatly reduce the tick population. Permethrin for the Lawn. Insecticides can reduce tick infestation by 90%. Insecticides should be applied in late spring or early fall in a strip a few feet wide along the perimeter of the lawn where small animals are likely to enter or live. The most commonly used insecticides are pyrethrins, which are compounds derived from the Chrysanthemum family. They are available as natural products or in synthetic forms (permethrin). They are poisons that affect the nerve system of insects. They are safe, particularly the natural products, for humans and pets. All pyrethrins are highly toxic for certain fish and slightly toxic for birds, such as mallard ducks. Some people do experience an allergic reaction to them. As with all insecticides, there is some concern about the possible consequences of long-term exposure, but to date there is no evidence of any harm. Cardboard tubes stuffed with permethrin-treated cotton are available in hardware stores. The tubes are placed where mice can find them (dense, dark brush) and collect the cotton for lining their nests. The pesticide on the cotton kills any immature ticks that are feeding on the mice. Best results are obtained with regular applications early in the spring and again in late summer. Other Pesticides. Other tick-killing spray pesticides that have been used include those containing diazinon, chlorpyrifos, and carbaryl. Animal studies have reported severe toxic effects associated with these chemicals. Some of these chemicals are being phased out for home use. Parents should balance the effects of a very negligible risk for a highly treatable infection versus excessive use of possibly harmful chemicals. Eliminating Risk from DeerFencing. Deer fencing, a wire fence about 3 - 4 yards high, or electrified fencing can be helpful, but it is costly to put up and maintain. Ivermectin. Corn that is laced with the anti-parasite medication ivermectin (Ivomec and others) and then eaten by deer helps prevent ticks from feeding on them. Ivermectin is present in a number of products used by veterinarians to control parasites, such as heartworm. It has potential toxic effects in collie or collie mixed breeds, however. Protective Clothing in the WoodsHiking and camping in the Northeastern woods carries a significant risk for tick bites and Lyme disease (3% in one study). Anyone out in the woods during tick season should wear protective clothing, including:
Simply washing clothes will not kill ticks. After venturing outdoors, people should run their clothes through a dryer at high temperature for a half hour. Spraying clothes with solutions containing permethrin (Permanone, Duranon, Permakill) affords additional protection. Keep in mind that these sprays should not be applied to the skin. Clothes should not be retreated with permethrin for 48 hours unless they are washed. Insect RepellentDEET. Most insect repellents contain the chemical DEET (N,N-diethyl-meta-toluamide), which remains the gold standard of currently available mosquito and tick repellents. DEET has been used for more than 40 years and is safe for most children when used as directed. Comparison studies suggest that DEET preparations are the most effective insect repellents now available. Concentrations range from 4% to almost 100%. The concentration determines the duration of protection. Most adults and children over 12 years old can use preparations containing a DEET concentration of 20 - 35% (such as Ultrathon), which provides complete protection for an average of 5 hours. (Higher DEET concentrations may be necessary for adults who are in high-risk regions for prolonged periods.) DEET products should never be used on infants younger than 2 months. According to the Environmental Protection Agency, DEET products can safely be used on all children age 2 months and older. The EPA recommends that parents check insect repellant product labels for age restrictions. If there is no age restriction listed, the product is safe for any age. The American Academy of Pediatrics recommends that children use concentrations of 10% or less; 30% DEET is the maximum concentration that should be used for children. In deciding what concentration is most appropriate, parents should consider the amount of time that children will be spending outside, and the risk of mosquito bites and mosquito-borne disease. When applying DEET, take the following precautions:
Picaridin. Picaridin, also known as KBR 3023 or Bayrepel, is an ingredient that has been used for many years in repellents sold in Europe, Latin America, and Asia. A product containing 7% picaridin is now available in the United States. Picaridin can safely be applied to young children and is also safe for women who are pregnant or breastfeeding. Insect repellents containing DEET or picaridin work better than other products for protection against ticks. Self-Inspection and Tick RemovalSelf-Inspection. The tick is unlikely to transmit the infection within 3 days of the bite, but prompt removal is still important. The following tips are important for self-inspection:
Tick Removal. If an attached tick is discovered, there is no reason to panic. Do not put a hot match to the tick or try to smother it with petroleum jelly, nail polish, or other noxious substances. This only prolongs exposure time and may cause the tick to eject the Lyme organism into the body. The safest and most effective way to remove an attached tick is:
VaccinesThe LYMErix Vaccine. The LYMErix vaccine, previously approved, was taken off the market because of poor sales and because of problems encountered with its use. A primary limitation was that the vaccine was effective only in about 75% of cases, and the effects were not long lasting. There were also reports of arthritic and neurologic symptoms in a few vaccinated people. There is no definitive evidence, however, that the vaccine was responsible for these symptoms. Protecting PetsSince dogs, cats and even horses can get Lyme disease, inspect pets for ticks regularly. Symptoms in animals include lameness and lethargy. Dogs are much more likely to get Lyme disease than cats, but both are susceptible. In dogs, symptoms occur 2 - 5 months after a tick bite and include fever, lameness, and lack of appetite. In rare cases, Lyme disease can cause kidney damage in dogs if it is left untreated. Preventive Products. Products containing permethrin (Bio Spot, EXspot), amitraz (Preventic), or fipronyl (Frontline) can be used safely on dogs. Not all of these products are safe in cats. Only permethrin is also effective against fleas. Some veterinarians suggest that the combination of BioSpot and Preventic is very effective. [Another product -- selamectin (Revolution) -- is sold for flea and tick control, but it appears to have very limited effect against ticks.] Pet Vaccines. Lyme disease vaccines are available for dogs, but they do not offer total protection. Veterinarians vary in their use of the vaccines. Treatment. As with people, antibiotics almost always cure the infection in animals. Human Granulocytic Anaplasmosis (HGA)In addition to Lyme disease, I. scapularis deer ticks can carry other types of infections that cause disease in humans. Human granulocytic anaplasmosis (HGA) is another illness spread by the deer tick. (HGA was formerly called human granulocytic ehrlichiosis. Another type of ehrlichiosis, human monocytic ehrlichiosis, is carried by a different type of tick.) Typical HGA symptoms appear very suddenly within 4 - 14 days of being bitten by an infected tick. Symptoms include headache, fever, chills, headache, and muscle pains. Vomiting, diarrhea, and loss of appetite are also common. Blood tests may indicate a low blood platelet count, low white blood cell count, and increased liver enzyme levels. HGA is caused by a species of bacteria called Anaplasma phagocytophilum. A blood test can identify the presence of this bacterium. All patients who show signs of symptoms should be treated with doxycycline to reduce the risk of complications. Another type of antibiotic, rifampin, is an alternative option for pregnant women, children younger than 8 years of age, or patients who are allergic to doxycycline. Treatment is not recommended for people who do not exhibit symptoms, even if they test positive for antibodies to A. phagocytophilum. BabesiosisThe tick that carries Lyme disease and human granulocytic anaplasmosis (HGA) can also carry babesiosis. Babesiosis is caused by a parasite called protozoa. It has been detected in about 10% of Lyme disease patients, and has been reported in Massachusetts, New York, Connecticut, Rhode Island, New Jersey, Minnesota, Wisconsin, Georgia, California, and Washington. When babesiosis is acquired from ticks, the infection occurs only in the summer. However, unlike in Lyme disease, blood transfusions have also been known to transmit babesiosis, so it can also occur other times of the year. The disease is still very rare, but people in tick-infested areas should be aware of it. Symptoms of BabesiosisSymptoms of babesiosis occur 1 - 4 weeks after a tick bite and are similar to those of malaria. Most cases are very mild and nearly unrecognizable. More severe symptom may resemble those in malaria and include:
Complications of BabesiosisIn healthy people, babesiosis generally causes only mild and temporary problems, but research indicates that the infection might persist in some people and may be spreading faster than previously reported. In rare cases, it can be severe and even life threatening, particularly in elderly people or those with chronic health problems or compromised immune systems. In such cases, the infection can cause altered mental states, anemia and other blood abnormalities, very low blood pressure, respiratory distress, and kidney insufficiency. Co-infection with Lyme disease may also increase its severity. Unfortunately, it is very difficult to diagnose. Treatment of BabesiosisBabesiosis is caused by a protozoon parasite, not a bacteria, so antibiotics alone won’t cure the disease. Treatment involves a two-drug combination of an anti-malaria medication and an antibiotic. The standard drug combinations are atovaquone (Mepron) plus azithromycin (Zithromax, Zmax) or clindamycin plus quinine. About 25% of patients cannot tolerate quinine. Adverse effects associated with quinine include hearing loss, tinnitus, stomach upset, diarrhea, and dizziness. Resources
ReferencesBakken JS, Dumler S. Human granulocytic anaplasmosis. Infect Dis Clin North Am. 2008 Sep;22(3):433-48, viii. Bratton RL, Whiteside JW, Hovan MJ, Engle RL, Edwards FD. Diagnosis and treatment of Lyme disease. Mayo Clin Proc. 2008 May;83(5):566-71. Centers for Disease Control and Prevention. Lyme disease -- United States, 2003-2005. MMWR Morb Mortal Wkly Rep. 2007 Jun 15;56(23):573-6. Clark RP, Hu LT. Prevention of lyme disease and other tick-borne infections. Infect Dis Clin North Am. 2008 Sep;22(3):381-96, vii. Feder HM Jr, Johnson BJ, O'Connell S, Shapiro ED, Steere AC, Wormser GP; Ad Hoc International Lyme Disease Group. A critical appraisal of "chronic Lyme disease." N Engl J Med. 2007 Oct 4;357(14):1422-30. Halperin JJ, Shapiro ED, Logigian E, Belman AL, Dotevall L, Wormser GP, et al. Practice parameter: treatment of nervous system Lyme disease (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2007 Jul 3;69(1):91-102. Vannier E, Gewurz BE, Krause PJ. Human babesiosis. Infect Dis Clin North Am. 2008 Sep;22(3):469-88, viii-ix. Wormser GP, Dattwyler RJ, Shapiro ED, Halperin JJ, Steere AC, Klempner MS, et al. The clinical assessment, treatment, and prevention of Lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2006 Nov 1;43(9):1089-134. Review Date: 2/11/2009
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