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Lyme Disease and Related Tick-Borne Infections
Highlights
Lyme Disease Tests
The U.S. Centers for Disease Control (CDC) recommends a two-step process for testing blood for the presences of yme disease:
- Step 1: Patients should first get an enzyme-linked immunosorbent assay (ELISA) or an indirect fluorescent antibody (IFA) test. If the test result is negative, the person probably does not have Lyme disease. If the test is positive, step 2 is advised.
- Step 2: Patients with a positive ELISA or IFA test should get a Western blot test to confirm the earlier test results.
In 2005, the CDC recommended against the use of all other types of Lyme disease tests due to a lack of scientific evidence regarding their accuracy.
Rocky Mountain Spotted Fever
Rocky Mountain spotted fever can turn up in unexpected places. According to the New England Journal of Medicine, a recent outbreak in Arizona was due to an expanding wild dog population. This tick-borne infection is most prevalent in southern parts of the United States, but can occur elsewhere. A spotted rash appear 5 to 10 days after infection. Rocky Mountain spotted fever can be fatal.
New Insect Repellent Recommendations
In 2005, the CDC recommended two new types of insect repellent products:
- Picaridin has been sold for many years in other countries. It is now available in the United States.
- Oil of lemon eucalyptus is a plant-based repellent that works as well as low concentrations of DEET. However, it should not be used on children younger than 3 years of age.
- According to the CDC, picaridin and DEET are the most effective types of insect repellents.
DEET Guidelines
DEET is still considered the best insect repellent, but recommendations for concentration levels vary:
- The Environmental Protection Agency suggests that any DEET concentration can safely be used on children older than 2 months.
- The American Academy of Pediatrics recommends that children use a lower concentration of DEET (less than 10%) and avoid DEET concentrations greater than 30%.
Introduction
Lyme disease is the most commonly reported vector-borne disease in the United States. Vector-borne infections are those that are transmitted by insects. Reports of U.S. Lyme disease cases peaked in 2002, when nearly 24,000 cases were reported.
Borrelia Burgdorferi
The Lyme disease infection in the US 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.
One of the most exciting advances in Lyme research was the completion of 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 Ticks
The vector that carries B. burgdorferi in the Northeast and North Central states is the Ixodes scapularis tick. The Ixodes scapularis tick goes through three stages over the course of about two years:
- It is born from eggs as a larva
- It develops into the nymph stage
- It develops into the adult stage
The Cycle of Infection
Cycle of Infection in the Northeast and North Central U.S. In order for Lyme disease to exist in these regions, three factors must come into close contact:
- The Borrelia (B.) burgdorferi spirochete
- The spirochete's host, the Ixodes scapularis tick
- The mammal for the tick to bite
The following describes the most common cycle in the Northeast and North Central US by which the Lyme disease infection eventually reaches a person:
- The cycle of infection is related to the tick's life cycle, which requires two years to complete. The tick typically first picks up the spirochete during its larva stage, when it needs a blood meal to mature further.
- The tick's initial meal is typically blood from the white-footed mouse, which is commonly infected with Borrelia burgdorferi. After it dines on the infected blood, the tick then becomes a carrier of this spirochete.
- Borrelia burgdorferi lodges in the tick throughout one of both of its following life stages, nymph and adult. It is during these stages that the infection is passed on to other animals, including humans. Nymph ticks emerge around mid-June and can be about the size of poppy seeds. They are very difficult to spot and are estimated to be responsible for 90% of all Lyme disease cases. Adult ticks can be as large as a raisin after feeding, and easy to spot, but they usually prefer their dinner on the white-tailed deer.
- The infected nymph or adult tick crawls (it does not fly or jump) onto another animal, which can be other mice or larger animals, such as deer, birds, or humans. If the tick bites such animals then it may then infect them with the B. Burgdorferi spirochete. (It should be noted that infected humans cannot pass the spirochete on to other humans by any means, including infected blood or urine or sexual contact.)
- A tick can feed for several days while being imbedded in the skin, after which it falls off. The tick's bite is painless, however, so only about half of people with Lyme disease recall being bitten.
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 Tick
The two other important infections carried by the Ixodes scapularis tick are ehrlichiosis 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 Lyme disease, human granulocytic ehrlichiosis (HGE), and babesiosis can all be carried by the same tick, 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 between 2 - 25% of ticks in several high-tick locations carry both HGE and Lyme. In a 2002 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.
Symptoms
Symptoms 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
- Stage 1. In the majority of cases, the first sign of early Lyme disease is the appearance of a bulls-eye skin rash. It usually develops about 1 to 2 weeks after the bite, although it may appear as soon as 3 days, and as late as 1 month. In some cases, it is never detected. Flu-like symptoms (joint aches, fever, and general fatigue) commonly develop.
- Stage 2. Untreated, the infection spreads through the blood stream and lymph nodes within days to weeks, involving the joints, nervous system, and possibly the heart. Multiple rashes may erupt in other places. If the infection affects the nervous system in stage 2, it most often causes weakness or paralysis in the nerves of the face (Bell's palsy) or in nerves of the spine.
- Stage 3. If the disease remains untreated, then within a few weeks or months a late or persistent infection can occur, which leads to prolonged bouts of arthritis and neurologic problems, such as concentration problems or personality changes. Fatigue is a prominent feature of both early and late stages.
Some people may develop a chronic set of symptoms called post-Lyme disease syndrome, although the definition and actual prevalence of this condition is unclear.
Skin Rash
Evidence suggests that up to 90% of patients with Lyme disease exhibit a rash a few days to a month after a tick bite. (Some experts argue that the rate of Lyme disease occurring without a rash is much higher, but more studies are needed to determine this.) The rash, known as erythema migrans, 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:
- It can first appear as a pimple-like spot, which expands over the next few days into a purplish circle. The circle may reach up to six inches in diameter with a deeper red rim. In some cases the ring is incomplete, forming an arc rather than a full circle.
- The center of the rash often clears or may turn bluish. Or secondary concentric rings may develop within the original ring, creating the bull's-eye pattern. Over the next several weeks, the circular rash may grow to as large as 20 inches across.
- Patients often describe the sensation of the rash as burning rather than itching.
It is important to note that in a 2002 study, only 9% of patients diagnosed with Lyme disease exhibited this classic pattern. Nearly 60% had a rash that was more general in appearance and 32% had a circular dense red rash.
In most patients, any rash fades completely after 3 or 4 weeks, although secondary rashes may appear during the later stages of disease.
Flu-like Symptoms
A 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 to 21 days and may include the following:
- Fatigue
- Chills and fever (100 to 103 degrees)
- Headache (usually most prominent at the back of the head)
- Joint aches (usually in the large joints)
- Stiff neck
- Backache
- Swollen glands (in the area around the tick bite or elsewhere)
- Less often, nausea, vomiting, and sore throat occur
Some experts recommend that children in high-risk areas be tested for Lyme in the summer months if they have the most common Lyme symptoms (fever, headache, joint aches)--even if they have no tell-tale rash. Severe and sustained flu symptoms without the rash in such patients may indicate the presence of human granulocytic ehrlichiosis (HGE) or babesiosis--the other infections carried by the Ixodes tick.
Conjunctivitis
The infection may appear in the eye in some people, causing inflammation and redness (conjunctivitis).
Arthritis
Joint pain can arise at any time after the appearance of a skin rash. In the absence of a rash, arthritic symptoms may be the first indication of Lyme disease. Or, as suggested by some studies, it can develop months after the disease has been diagnosed. Arthritic symptoms may occur as follows:
- Aches, stiffness, and swelling, sometimes massive, of large joints, such as the knee, elbow, or shoulder. One or both knees are affected most often. The ankle, wrist, jaw, and finger joints are involved less often.
- Typically, no more than three joints are affected during the course of the disease. If several joints are involved, they tend to be asymmetrically distributed.
- Joint pain flare-ups are often accompanied by muscle pain.
- Arthritis symptoms usually last for a few days or weeks and are interspersed with longer periods during which the joints feel fine.
- The severity and frequency of attacks peak within a year or two then decrease and usually resolve, even without treatment.
Neurologic Symptoms
About 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 between 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:
- Episodes of headache not relieved by over-the-counter medication
- Mild stiff neck
- Sensitivity to light
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:
- Unexplained mood changes
- Depression
- Trouble concentration and remembering
- Irritability
- Feelings of "pins and needles" or numbness in the arms or legs
Other Neurologic Symptoms.
- If the infection affects the white brain matter, symptoms resemble multiple sclerosis.
- If the infection occurs in the nerves affecting the skin, some patients experience pricking, tingling, or creeping feelings.
- Children have a higher risk than adults for neurologic effects on the eye. (This is still rare, however.)
- Some parents have reported more severe mental changes in children diagnosed with Lyme disease, including depression and mood changes, anxiety, attention deficit disorder, learning disabilities, poor school performance, and even psychotic behavior. Well-conducted studies are needed to determine if these reports have any significance.
Heart Symptoms
The infection may affect electrical conduction to the heart and cause symptoms suggesting heart rhythm disturbances:
- Palpitations
- Shortness of breath
- Chest pain
- Dizziness
- Fainting can occur if the infection affects the heart
These symptoms almost never produce serious problems in people without other types of heart disease.
Eye Symptoms
Symptoms in the eyes have been reported at every stage. Conjunctivitis ("pink eye") may be a symptom in the early stages. In late, untreated Lyme disease, neurologic problems can affect the eye, causing pain and sensitivity to light.
Risk Factors
The Centers for Diseases Control (CDC) reports that more than 145,000 Lyme disease cases have been diagnosed since 1982. Reports of Lyme disease cases in the U.S. peaked in 2002 when nearly 24,000 cases were reported that year. Lyme disease is now the most common vector-borne disease in America. (Vector-borne infections are those that are transmitted by insects.)
General Risk Factors
Anyone 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. In the U.S., the highest reported incidence of Lyme disease occurs among children 5 to 9 years old and adults 50 to 59 years old.
Gender. The reported incidence is higher for females than for males. The gender discrepancy may be attributable to increases in the following:
- Exposure to infected ticks
- Less use of personal protective measures
- Men may tend to report symptoms less often than women
The Risk for Lyme Disease After a Tick Bite
In general, the actual risk for developing Lyme disease after a tick bite is only between 1 - 3%. The risk varies depending on different factors:
- The longer the tick has fed the greater the risk. In fact, in one study, no individuals developed Lyme disease after being bitten by a nymph tick for less than 72 hours. In those on whom the tick had been feeding for longer than that, the risk was 25%.
- Nymph ticks carry a greater risk than adult ticks, probably because they are often too small to be detected (about the size of a pinhead). In addition, only nymph ticks that are at least partially swollen when removed pose any significant risk. (This suggests that they have feeding for a prolonged period.)
Geographic Locations
Locations in the U.S. In 2002, Lyme disease was reported in all states except Hawaii, Montana, and Oklahoma. However, nearly all of Lyme disease cases are concentrated in three regions:
- In northeastern states from Maine to Maryland.
- Two northcentral states (Minnesota and Wisconsin)
- In the northwest (California and Oregon)
In such areas, between 1 - 3% of people who live there become infected at some time. New York has had the highest number of total cases to date, followed by Connecticut, which actually has the highest number of infected patients per total population. Pennsylvania and New Jersey have the next highest infection rates.
One interesting report found that the blood of the Western fence lizard contains a chemical that destroys B. burgdorferi, the Lyme disease spirochete. The presence of this lizard may help explain the low incidence of Lyme disease in western states. Experts differ on whether Lyme disease exists with any significance in the southern United States. A Lyme-like disease has been reported in the south (Mississippi, South Carolina, Georgia, Florida, and Texas), which apparently responds to antibiotics (as Lyme does). Researchers have also identified spirochetes on Lone Star ticks that appear to belong to the Borrelia family. Studies are underway to determine the exact nature and extent of this condition.
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 Landscapes
One analysis suggested the risk for Lyme disease exposure is highest in wet, green areas, and lower in areas with lawns or low vegetation. Hiking and camping in the Northeastern woods carries a significant risk for tick bites and Lyme disease.
The disease is not limited to rural settings. It is becoming increasingly common in suburban areas. Beaches are also home to ticks.
Time of Year
The time of year of highest risk depends on the geographical region.
Northeast and North Central U.S. In the northeastern and north central U.S., most cases of Lyme disease are reported from May through August, with July being the peak month.
Exceptions may occur in years of warm winters and wet springs, which can bring the deer tick nymphs out about 2 weeks earlier. This same climate also creates the wet, green environment that increases the prevalence of ticks.
Noncoastal Western States. In the noncoastal western U.S., the disease most often occurs between January and May.
West Coast. The risk is higher on the west coast between November and April.
Complications
Prompt treatment with antibiotics is very effective in curing Lyme disease in nearly all infected people, including children. A 2003 study showed that the long-term outcome of patients with Lyme disease who are treated with antibiotic therapy is excellent. However, even if Lyme disease has been successfully treated, it may be possible to become reinfected with Lyme disease again at a later date. The risk appears to occur only in patients who had been treated for the rash. In those who also developed arthritic symptoms, the antibody response appears to persist and prevent reinfection.
Complications of Late-Stage Lyme Disease
People 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 an estimated 10% will continue to have problems. Also at risk for persistent symptoms are those who show evidence of having severe infections. Retreatment at later stages has been shown to be effective in about three quarters of these patients.
Left untreated, Lyme disease can spread (disseminate). The infection may affect almost any part of the body and cause the following complications:
- Severe arthritis
- Persistent fatigue
- Mood disturbances and loss of concentration
- Neuropathy (numbness, tingling, or other odds sensations in the hands, arms, feet or legs)
- Life-threatening disorders affecting the heart, lungs, or nervous system can occur, but are very rare
Chronic Arthritis. Without treatment, 60% of patients develop intermittent joint inflammation, especially in the knees. After several severe attacks the condition may become chronic, but it often responds to intravenous or long-term oral antibiotics.
About 10% of treated patients experience persistent pain in the joints. Researchers are trying to determine if this represents and actual chronic infection caused by the spirochete or if it is a persistent and abnormal immune response. In the later case, antibiotics are not effective. To date, investigators have not detected higher levels of immune factors ordinarily associated with inflammation, although one study reported increased traffic of B cells into the affected tissues. B cells are important immune factors in producing infection fighters, which can trigger inflammation.
Persistent Neurologic Disorders. In general neurologic problems persist in 5% of patients, although some studies have reported much higher rates of up to 50%. Persistent symptoms usually include headache, attention and memory problems, and depression. Patients may also experience neurologic pain, numbness, or abnormalities in the face. Neurologic symptoms generally resolve and improve within a year.
Heart Problems. About 5% of untreated patients experience acute heart events from electrical conduction problems caused by the infection. Heart symptoms can appear within a few days to several months after the onset of disease. They include:
- Arrhythmias (irregular heartbeats)
- Pericarditis (inflammation of the lining of the heart), which occurs in about 5% of patients
Lyme-related heart problems nearly always resolve without serious consequences within a week. About 30% of patients may need a temporary pacemaker, however. In very rare cases, these heart rhythm abnormalities have been fatal. There is some debate about whether there are any long-term consequences to the heart, such as the development of heart failure in some patients. One study of patients who had had Lyme-related heart effects reported no greater long-term risk for heart problems than in people without a history of Lyme disease.
Miscellaneous Complications. Other complications reported include:
- Problems in the eye, including swelling that can cause pain and sensitivity to light
- Hepatitis (inflammation in the liver)
- Respiratory difficulties
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.
- Some studies indicate that Borrelia burgdorferi may be transmitted to the fetus during pregnancy, with the risk highest during the first trimester. If this occurs, however, it is likely to be very rare and not an issue of great concern. There is no evidence of any severe effects in the offspring of infected pregnant women.
- There are no reports of human infant Lyme disease infection from breast feeding. Studies on animals, however, have reported transmission of the organism to infant mice through breast milk, but these findings do not appear to be applicable to people.
Post-Lyme Disease Syndrome
Symptoms persist in many patients after antibiotic treatment, although reports vary as to duration and location of symptoms. In general, about a third of patients have symptoms that last a few weeks. In 10 - 15% of cases, patients complain of persistent symptoms such as fatigue, muscle aches, and headache lasting years after completing antibiotic treatments for the initial infection. This syndrome, which resembles chronic fatigue syndrome (CFS) or fibromyalgia, is referred to as chronic Lyme disease, or post-Lyme disease syndrome. It seems to be reported more frequently in patients who experienced early neurologic symptoms during the initial infection, particularly if their treatment was delayed.
Much controversy surrounds chronic Lyme disease, however, including whether it represents an actual persistence of the original infection, whether it is a persistent inflammatory reaction to the infection, and whether it can be treated.
In most cases of post-Lyme syndrome, advanced diagnostic techniques fail to detect any persistent infection. (Even if there is some evidence of residual immune activity, it does not mean that the Lyme infection is active.) Some doctors contend, however, that Lyme disease was inadequately treated to begin with and that the infection persists, but that the antibody levels are too low to be detected. These doctors recommend intensive antibiotic treatments. However, the majority of experts are opposed to long-term, intensive antibiotic treatment.
A number of studies have reported no differences between groups of patients with post-Lyme disease syndrome who received intensive antibiotic treatments versus those who received placebo. In addition, other studies have reported no evidence of persistent Borrelia infection in many patients with post-Lyme disease syndrome. These results strongly suggest that the condition in some patients has other causes.
Different experts have suggested the following causes for the conditions:
- It may be due to a persistent and abnormal immune response. In such cases, the patient develops an autoimmune response, in which the body produces immune factors that target its own cells and causes inflammation and injury.
- The persistent symptoms may be due to an initial misdiagnosis and many of these patients never had Lyme disease to begin with.
- A co-infection with ehrlichiosis, babesiosis, or other tick-borne pathogens may be the cause of persistent symptoms in many of these patients.
- Because symptoms of post-Lyme syndrome are so nonspecific, some doctors believe they are simply psychological. Others believe that such thinking is a disservice to patients who experience genuine suffering and pain. Depression is certainly a common symptom of both early and late-stage Lyme, but may be a physical result of the disease.
Overall, studies report a low incidence of chronic Lyme disease. Reports from centers that have years of experience treating Lyme disease in children have been reassuring and state that there are very few cases of long-term or untreatable illness.
Diseases with Similar Symptoms
Various features of Lyme disease can be mimicked by many other illnesses. 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 Infections
Other 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 ehrlichiosis (HGE) are transmitted by the same tick that carries Lyme disease. People are often coinfected with one or more of these infections, which can all 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 coinfection 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 prevalent in other parts of the country.
- Tick-borne relapsing fever, a flu-like illness that occurs in mountainous areas of the West during the summer, may be under-reported and misdiagnosed as Lyme disease.
- Rocky Mountain spotted fever, which is also transmitted by ticks, is most prevalent in the south central and southeastern parts of the United States, but occurs throughout North and South America. The most characteristic symptom is a spotty rash that appears 5 to 10 days after infection. The disease is caused by ticks that carry the bacterial organism Rickettsia rickettsii, and is considered the most severe tick-borne illness in the United States. Unlike Lyme disease, which is rarely fatal, Rocky Mountain spotted fever causes death in 10% of all cases. Recent outbreaks of Rocky Mountain spotted fever have been linked to increases in wild dog populations.
- A tick-borne infection carried by the Lone-Star tick strongly resembles Lyme disease, including a similar rash. It is not caused by the Lyme spirochete, however, and has been identified in patients who live in the southern United States.
Researchers speculate that ticks may be responsible for other diseases not previously thought to be carried by these vectors. For example, the Bartonella family of bacteria causes cat-scratch fever (which is transmitted from cat to cat by fleas) and trench fever (historically transmitted by lice). Common Rashes
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 Diseases
A number of autoimmune diseases have chronic and low-level symptoms that may be confused with either acute or chronic Lyme disease.
- Systemic lupus erythematosus (SLE) produces a rash (usually on the face), flu-like symptoms, and arthritis, but they usually develop very slowly over time.
- Rheumatoid arthritis or Reiter's syndrome causes pain, swelling, or stiffness of the joints that may be confused with post-Lyme syndrome.
- Scleroderma has a limited form of the disease called morphea, which produces hard patches of skin. Some studies have even reported an association between B. burgdorferi and some cases of morphea. However, the evidence is weak and if it exists it is possibly limited to a specific variant in Europe and Asia. There is no association between severe scleroderma and Lyme disease.
- In children, juvenile rheumatoid arthritis or rheumatic fever, which follows strep throat, should be considered.
Diseases Resembling Post-Lyme Syndrome
A number of conditions cause chronic fatigue and joint and muscle aches that resemble descriptions of post-Lyme syndrome.
- Mononucleosis -- this virus infection is common in teenagers
- Chronic fatigue syndrome (CFS)
- Fibromyalgia
Depression
Depression that may be mistaken for post-Lyme syndrome is marked by physical symptoms, including persistent fatigue and vague aches and pains.
Meningitis
The 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 bulls-eye rash.
Diagnosis
Proper diagnosis of Lyme disease is important. A diagnosis of Lyme disease is straightforward if the patient meets the following criteria:
- Lives in an area of tick-infestation
- Has the tell-tale bulls-eye rash
- Has other symptoms (headache, joint aches, malaise, flu-like symptoms)
If the patient has all of these symptoms, except the rash, then the doctor may undertake the enzyme-linked immunosorbent assay (ELISA) or the Western Blot test.
Culture
In some cases, if the patient seeks a diagnosis within the first 2 to 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 Testing
If 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:
- Proteins referred to as Osps. These proteins (referred to as Osp A through F) coat the outer surface of the B. burgdorferi spirochete and then attach to human cells after infection.
- Antibodies that attack these Osps. Antibodies are the weapons of the immune system that are launched when a foreign invaders (called antigens) are detected. In the case of Lyme disease, these antigens are the Osps.
Specific Tests.
The U.S. Centers for Disease Control (CDC) recommends a two-step process for Lyme disease blood tests:
- ELISA and Other Initial Tests. The first tests used are either enzyme-linked immunosorbent assay (ELISA) or an indirect fluorescent antibody (IFA) test. ELISA is the immune test used most often for Lyme disease. (The IFA test is less accurate but may be used when ELISA isn't available.) ELISA measures antibodies that are directed against the B. burgdorferi spirochete. A newer variant is a rapid test (PreVue) that can provide results within an hour. Positive results from any of these tests still require confirmation with a Western blot test. Negative results do not require further testing.
- Western Blot. If any of these tests is positive or uncertain, then they are followed by the Western immunoblot (WB), which is more accurate and is very helpful in confirming the diagnosis. The Western blot creates a visual graph showing bands of different colors or shading that experts use to interpret the immune response.
The CDC recommends only these tests. In 2005, the CDC warned against tests such as urine antigen, immunofluroescent staining, and lymphocyte transformation that 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.
Either 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:
- The antibodies to the infectious organism triggering the antibodies are not the Lyme spirochetes. Other organisms that can trigger such antibodies include syphilis and relapsing fever. Dental infections may trigger a false positive response.
- The patient may have been infected with Lyme disease previously and harbor antibodies to the disease.
False negative results are those that 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:
- The test is taken too early in the course of Lyme disease. In such cases, the antibodies that fight the spirochete might not have reached a level that is high enough to be detected. (Only about 20 - 30% of patients can be identified using immune system tests in the first 2 to 4 weeks. By the fourth week, up to 80% of patients will have detectable antibodies.)
- The patient has taken certain medications, such as steroids or certain anti-cancer drugs, which reduce the immune system's ability to produce antibodies, including those in response to Lyme disease.
- There are too many infection-fighting antibodies attached to the bacteria. In this case, there are not enough loose antibodies in the blood sample to trigger a response.
- The laboratory itself has set its sensitivity point too high. Some laboratories establish a standard of very high antibody levels before the test results will trigger a finding of Lyme disease. (They do this to avoid too many false-positive responses.) In so doing, however, their tests may miss the disease in patients with lower antibody levels. A related diagnostic problem concerns the possibility of missing persistent Lyme disease after antibiotic treatments, when antibody levels would be low.
In summary, a negative blood test does not rule out a diagnosis of Lyme disease, particularly if symptoms strongly suggest its presence. Conversely, a weakly 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) Test
The 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 Involvement
Analysis 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.
Treatment
Antibiotics are the drugs of choice for all phases of Lyme disease. In nearly all cases they can cure Lyme, even in later stages. It should be noted that these recommendations apply only to Lyme disease in the US. The organisms that cause Lyme disease in Europe may require different treatments.
Preventive Antibiotics After a Tick Bite
An expert group has recommended that people bitten by deer ticks should not routinely receive antibiotics to prevent the disease.
Nevertheless, an important study in 2001 reported that a single 200-mg dose of the antibiotic doxycycline given within 72 hours of the tick bite was effective in preventing disease (87% protection). If 72 hours have passed, simply waiting for symptoms and then treating the disease at that point is very effective and cures nearly all cases..
In general, the risk of developing Lyme disease after being bitten by a tick ranges from only 1 - 3%. The only people who still might need preventive antibiotics are unvaccinated individuals in high-risk areas who have been bitten by ticks that are in the nymph stage and that are at least partially swollen after feeding. (Adult ticks or nymph ticks that are not swollen pose a very low risk.)
Treating Early Stage Lyme Disease
Three to four weeks of either doxycycline or amoxicillin is the standard regimen. The following are treatment guidelines for treating patients who have been bitten by a tick and have symptoms or a reasonably clear diagnosis of early Lyme disease:
- Doxycycline. This antibiotic is effective against both Lyme disease and ehrlichiosis and so is the standard antibiotic for any patient over 8 years old (except pregnant women). It may also be effective for patients with Bell's palsy (although such patients may have other neurologic problems that need more aggressive treatments). Doxycycline cannot be used routinely in children under 8 years old. It is a form of tetracycline and as such discolors teeth and inhibits bone growth. It can also cause birth defects, so it should not be used during pregnancy.
- Either amoxicillin (one of the penicillins) or cefuroxime (Ceftin)--a drug known as a cephalosporin--is the alternative for young children. Amoxicillin is the first choice and also probably the best antibiotic for pregnant women. Unfortunately, many people are allergic to penicillin. In addition, strains of bacteria are emerging that are resistant to penicillins. Either drug is usually given for 20 days. Large studies are needed to determine which drug is more effective in children.
- Erythromycin or similar antibiotics called macrolides are used if none of these drugs are appropriate.
- Intravenous ceftriaxone--another cephalosporin--is usually warranted if there are signs of infection in the central nervous system (the brain or spinal region).
A 2003 study suggested that a 10-day regimen of doxycycline was sufficient for curing most cases. The duration is a matter of some debate, since many doctors are concerned about persistent symptoms and so prescribe the antibiotic for 20 days. Whether prescribing antibiotics for longer periods of time adds any benefit, however, is uncertain and controversial. For example, according to the same 2003 study, extending the duration to 20 days did not prevent persistent Lyme symptoms any more effectively than the 10-day regimen.
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 the doctor all medications they are taking.
Treating Late Stage Lyme Disease
Lyme Arthritis. Either oral doxycycline (about 2 months) or intravenous ceftriaxone (1 month) are options for Lyme arthritis. The oral antibiotic has fewer side effects and is less expensive. Some patients on the oral medication, however, develop neurologic Lyme complications, which then require intravenous antibiotics. Newer potent oral antibiotics are under investigation. Patients should discuss these issues with their doctor.
Lyme Encephalopathy and Other Neurologic Symptoms. Intravenous (IV) antibiotic treatments (usually ceftriaxone) are typically used for 21 to 30 days. Good alternatives are intravenous cefotaxime or penicillin G. This treatment is nearly always successful in treating Lyme encephalopathy. Symptoms usually resolve in a week, but in some cases it can take months.
Heart Arrhythmia. Lyme disease, in some cases, effects the electrical conduction to the heart and can disrupt heart rhythms. Mild heart involvement usually responds to oral antibiotics. Severe disturbances in heart rhythms require intravenous antibiotics. Heart monitoring is important. For some patients, it may be necessary to insert a pacemaker for a week or two, although a permanent pacemaker is rarely needed.
Treating Post-Lyme Disease Syndrome
In about 10% of cases after treatment symptoms persist, a condition referred to as post-Lyme disease syndrome. In such cases, patients have persistent fatigue, muscle and joint aches, and neurologic symptoms. Treatment for this syndrome is highly controversial.
Intravenous Antibiotics. Some doctors believe that patients with such chronic symptoms have been inadequately treated previously. They recommend extremely aggressive treatments with 30 days of intravenous antibiotics followed by a month of oral doxycycline. This approach has some significant risks.
An important 2001 study compared a group of patients with this antibiotic regimen with a group that received a placebo. All of these patients had been previously treated for Lyme and reported persistent pain, fatigue, and neurologic symptoms. After treatment, there were no differences among any of the treatment approaches, including the placebo. In general, 36% of patients improved, 39% worsened, and 25% experienced no change. None of the patients showed any evidence of persistent infection with B. burgdorferi. Two 2004 studies confirmed that additional antibiotics have no beneficial effects on patients with Lyme disease symptoms who had previously received antibiotic therapy.
Such findings do not mean that post-Lyme disease syndrome is simply a psychologic problem, but rather that this condition is probably not treatable with antibiotics. Such patients still require a careful and well-thought out treatment plans.
Other Treatments. Some other approaches for post-Lyme disease syndrome include:
- Pain control and cognitive behavioral therapies may be helpful. Cognitive behavioral treatment, which helps patients learn to cope and manage their symptoms, may be very helpful. According to one study, this process can take many months of three to four sessions a week before the patient experiences its full benefits.
- Some experts believe that the condition is caused by a persistent and abnormal immune response. In such cases, anti-inflammatory drugs may be tried.
- In rare cases of severe and persistent arthritis of the knee or other joints, surgery may be required.
Alternative Therapies. Some individuals 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 exists on their benefits. 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. Any such therapies should be discussed with a doctor.
Herbs and SupplementsGenerally, 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. |
Prevention
Everyone should avoid specific tick-infested areas, including tall grass, woods, and bushes where ticks tend to congregate. If this is not possible, then people should take additional preventive measures. The CDC also recommends:
- Use of tick repellant
- Routine tick checks --removal of infected ticks within 48 hours of attachment substantially reduces the likelihood of transmission
- Prompt antibiotic prevention for tick bites -- although this method is controversial, the CDC concludes that it is probably beneficial
- Removing brush and leaves -- such landscaping measures can reduce transmission rates by 50 - 90%.
- Use of pesticides to yards once or twice per year, which can decrease the number of ticks by 68 - 100%
Protecting Property from Tick Infestation
Mowing 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.
Damminix, available in hardware stores, consists of cardboard tubes stuffed with permethrin-treated cotton. The tubes are placed where mice can find them (e.g., 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. As many neighbors as possible should use it to be effective. (It is not effective on the West Coast.)
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 Deer
Fencing. Deer fencing, a wire fence about three to four yards high, or electrified fencing can be helpful, but it is costly to put up and maintain.
Ivermectin. Corn that is laced with ivermectin (Ivomec and others) and then eaten by deer helps prevent ticks from feeding on them. It should be noted that 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 Woods
Hiking 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:
- Light-colored clothing -- makes it easier to spot ticks
- Long-sleeved shirts and long pants with cuffs tucked into shoes or socks
- High boots, preferably rubber boots
- Tick-collars for small dogs -- can be worn around a person's ankles over socks or pants
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 Repellent
DEET. 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. Experts recommend that most adults and children over 12 years old 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, the following precautions should be taken:
- Do not use on the face and apply only enough to cover exposed skin on other areas.
- Do not over apply and do not use under clothing.
- Do not apply over any cuts, wounds, or irritated skin.
- Parents or an adult should apply repellent to a child and not let the child apply it him- or herself. They should first put DEET on their own hands and then apply it to the child. They should avoid putting DEET not only near the child's eyes and mouth, but also on the hands (since children frequently touch their faces).
- Wash any treated skin after going back inside.
- If using a spray, apply DEET outdoors--never indoors. Spray repellents should not be applied inside or directly on anyone's face.
Other Insect Repellent Products. In 2005, the U.S. Centers for Disease Control (CDC) added two new mosquito repellents to its list of recommended products: Picaridin and oil of lemon eucalyptus.
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. According to the CDC, insect repellents containing DEET or picaridin work better than other products.
In scientific tests, oil of lemon eucalyptus, also known as PMD, worked as well as low concentrations of DEET. However, oil of lemon eucalyptus is not recommended for children under the age of 3 years.
Self-Inspection and Tick Removal
Self-Inspection. The tick is unlikely to transmit the infection within three days of the bite, but prompt removal is still important. The following tips are important for self-inspection:
- Ticks responsible for Lyme disease are very small and may resemble freckles or scabs.
- People spending time in tick-infested locations should inspect themselves several times a day, including at bedtime.
- Check nonexposed areas, such as the back of the knee, as well as exposed areas. Someone else should check the scalp, back of the neck, and other difficult to reach areas.
- Check clothing as well as skin. A tick on can be hidden in folds or creases.
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 the following:
- Grasp the tick's mouth area with clean tweezers as close to the skin as possible. (Take care not to handle it with bare fingers as this can also spread infection.)
- Next, pull upward with a steady even pressure. Do not twist, crush, or squeeze the body area of the tick, because this region contains the infectious organism. In fact, do not be alarmed if some of the mouth parts remain in the skin. They are not infectious.
- Put the tick in a jar or container of alcohol, which will kill it. Some people lay a piece of adhesive tape to the top of the tick and fold it over, without touching the insect. Then they simply throw it away. Tape is also effective for trapping a tick that has not yet attached to the skin.
- Once the tick is removed, wash the bite area with soap and water or with an antiseptic to destroy any contaminating microorganisms. Wash hands as well.
Vaccines
The 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 is that the vaccine was effective only in about 75% of cases and the effects are not long lasting. There were also reports of arthritic and neurologic symptoms in a few vaccinated people, however there is no evidence at this time that the vaccine was responsible for these symptoms. In fact, a 2002 study based on the major government vaccine reporting system of 1,400,000 doses reported no unusual adverse side effects, although there was a higher risk for allergic reactions than expected. It should be noted, however, that most patients do not report their symptoms to this system.
Other Vaccines. Deer ticks lay their eggs on mice and other small rodents. These eggs develop into larvae that feed on these small animals. When the larvae develop into nymphs, they seek a larger host like a deer or human. Scientists are exploring the idea of vaccinating mice and other rodents against B. burgdorferi. Inserting an oral vaccine into these animals’ food supply helps reduce the number of nymph ticks and may be a more effective preventive strategy than vaccinating humans. Recent studies suggest that vaccination of mice produces 89 – 100% protection from B. burgdorferi infection.
Protecting Pets
Since dogs, cats and even horses can get Lyme disease, pets should be inspected 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 two to five months after a tick bite and include fever, lameness, and lack of appetite. In rare cases, it can cause kidney damage if it is 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. And, 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.
Ehrlichiosis
Ehrlichiosis refers to several tick-borne diseases caused by very small organisms called Ehrlichiae, which affect both humans and animals. Ehrlichiae are gram negative bacteria that infect and destroy white blood cells. Two human diseases are caused by varieties of Ehrlichiae found in the U.S.
- Human monocyte ehrlichiosis (HME) infects white cells known as monocytes. More than 1000 cases of HME have been reported since it was first identified in 1986. It is caused by the bacterium Ehrlichiachaffeensis and is carried by the Lone Star tick, found primarily in the southcentral and southeastern U.S.
- Human granulocytic ehrlichiosis (HGE) infects granulocyte white blood cells. It is more likely than HME to be carried by adult Ixodes ticks and so is most often found northeastern and upper midwestern states.
Ehrlichiosis caused by other or unspecified organisms is a new category that was added in 2000 to account for other cases of these bacteria that have been detected.
Both HGE and HME have been reported in Europe. In fact, a Swedish study reported an almost equal prevalence of ehrlichiosis and Lyme disease in one population group. The European form of HGE appears to be a less severe condition than in the U.S. HME has also been reported in Africa.
Some studies indicate that middle-aged and elderly men are most likely to be infected with either form of ehrlichiosis.
Symptoms of Ehrlichiosis
Ehrlichiosis usually develops rapidly. Patients who are infected with ehrlichiosis will begin to feel symptoms between 3 to 16 days after being bitten by an infected tick. A patient may feel fine early in the day only to experience very severe, debilitating symptoms a few hours later. While ehrlichiosis is often very mild, with only flu-like symptoms, in some cases, symptoms can be severe:
- Rash -- about one-third of HME patients and a smaller proportion of HGE patients develop a rash; the rash does not form a circle as it does in Lyme disease
- Fever
Other common symptoms may include:
- Malaise
- Confusion
- Severe headache
- Muscle and joint aches
- Chills
- Cough
- Nausea, vomiting, and lack of appetite
In serious cases, the patients may develop mental abnormalities, breathing difficulties, and kidney problems. Symptoms that affect the central nervous system, including seizures, coma, a stiff neck, sensitivity to light, and others, may be mistaken for meningitis. There does not appear to be a chronic phase for the ehrlichiosis, although much is still unknown about the disease.
Outlook and Complications of Ehrlichiosis
Some experts estimate that only about 10% of people infected with ehrlichiosis develop symptoms, which are often so mild and flu-like that probably many people recover without seeking either a diagnosis or treatment. In symptomatic patients, however, ehrlichiosis can be more severe than Lyme disease. In studies of reported cases of both HME and HGE, 57 - 62% percent of patients required hospitalization, and estimated morality rates were 5% for HME and 10% for HGE. These percentages, however, probably reflect an overrepresentation of serious cases, and there is some evidence that they are significantly lower (2.7% for HME and 0.7% for HGE). The accuracy of any figures relating to ehrlichiosis is uncertain because there are so few cases.
In general, it is important to initiate treatment for ehrlichiosis as soon as possible. The longer a patient is untreated, the worse the outcome will be. The disease is more severe in the elderly, those with anemia, and people with impaired immune systems such as those with AIDS. HME may be more severe in children because initial symptoms are often mild and even doctors are often unaware of it. The following are severe complications associated with ehrlichiosis when left untreated:
- Either form of ehrlichiosis can damage white-blood cells to the point where a patient can die from serious infections such as fungal pneumonia.
- HGE may infect young white blood cells in the bone marrow, which are then released into general circulation. Infected white blood cells can affect in the spleen, liver, lymph nodes, bone marrow, lung, kidney, and cerebrospinal fluid.
- Signs of central nervous system abnormalities, such as changes in mental state, are indicators of a very dangerous condition.
Ehrlichiosis does not appear to have a chronic phase as Lyme disease does, although blood tests of patients previously treated indicates that the infection persists in many cases. At this time not enough is known about ehrlichiosis to come to any confident conclusions about long-term effects.
Diagnosing Ehrlichiosis
A diagnosis of HME or HGE is based on observation of the patient's symptoms, usually supported by immunofluorescence assay or polymerase chain reaction tests. Few doctors, however, are aware of ehrlichiosis, and even the knowledgeable ones are unable to diagnose ehrlichiosis simply on the basis of symptoms. Experts suggest that doctors consider a diagnosis for ehrlichiosis in the following patients:
- Those with fever and flu-like symptoms who report being bitten by a tick
- Those whose blood tests indicate lower amounts of white blood cells and platelets and elevated liver enzyme levels
During the convalescent stage of ehrlichiosis, blood samples can be examined for antibodies to the organism, but even these are positive in only 80 - 87% of cases of HME. Researchers are currently working on laboratory tests to facilitate more precise diagnoses of ehrlichiosis.
Treating Ehrlichiosis
When treated early, ehrlichiosis responds very well to the antibiotics tetracycline, doxycycline, and rifampin. Some experts report that it is effectively treated for a minimum course of 5 to 7 days. If ehrlichiosis goes untreated, however, it can escalate into a life-threatening condition.
Unfortunately, it does not respond to most of the antibiotics commonly used for Lyme disease, including ampicillin, ceftriaxone, erythromycin, ciprofloxacin, and azithromycin. It is important, then, if ehrlichiosis is at all suspected, to give patients antibiotics, most often doxycycline, that are effective against both tick-derived diseases.
Babesiosis
The tick that carries Lyme disease and ehrlichiosis also can carry babesiosis. Babesiosis is 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 Babesiosis
Symptoms of babesiosis occur 1 to 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 the following:
- Headache
- Fever and chills, with night sweats
- Nausea and vomiting
- Muscle aches
- Anemia
Complications of Babesiosis
In healthy people, babesiosis generally causes only mild and temporary problems, but research indicates that the infection might persist in some people and is 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. Coinfection with Lyme disease may also increase its severity. Unfortunately, it also very difficult to diagnose.
Treatment of Babesiosis
Babesiosis is a protozoa, not a bacteria. It does not respond to conventional antibiotics. Standard treatment at this time is clindamycin (an antibiotic) and quinine sulfate. About 25% of patients cannot tolerate quinine, however. Adverse effects associated with quinine include hearing loss, tinnitus, stomach upset, diarrhea, and dizziness.
One study suggested that a combination of atovaquone and azithromycin was as effective as clindamycin and quinine and had fewer side effects. The most common adverse effects were rash and diarrhea. Other combinations used are atovaquone, an antimalarial drug, and azithromycin, an antibiotic. Blood transfusions may also be helpful in some patients.
Resources
- www.niaid.nih.gov -- National Institute of Allergy and Infectious Disease
- www.cdc.gov/ncidod/dvbid/lyme -- Centers for Disease Control
- www.lyme.org -- Lyme Disease Foundation
- www.aldf.com -- American Lyme Disease Foundation
- www.lymenet.org -- Lyme Disease Network
- www.idsociety.org -- Infectious Diseases Society of America
- www.rheumatology.org -- American College of Rheumatology
- www.arthritis.org -- The Arthritis Foundation
References
U.S. Centers for Disease Control and Prevention. Caution regarding testing for Lyme disease. MMWR Morb Mortal Wkly Rep. 2005;54(5):125.
Coulter P, Lema C, Flayhart D, Linhardt AS, Aucott JN, Auwaerter PG, et al. Two-year evaluation of Borrelia burgdorferi culture and supplemental tests for definitive diagnosis of Lyme disease. J Clin Microbiol. 2005;43(10):5080-5084.
Demma LJ, Traeger MS, Nicholson WL, Paddock CD, Blau DM, Eremeeva ME, et al. Rocky Mountain spotted fever from an unexpected tick vector in Arizona. N Engl J Med. 2005;353(6):587-594.
Dumler JS, Walker DH. Rocky Mountain spotted fever--changing ecology and persisting virulence. N Engl J Med. 2005;353(6):551-553.
Gomes-Solecki MJ, Brisson DR, Dattwyler RJ. Oral vaccine that breaks the transmission cycle of the Lyme disease spirochete can be delivered via bait. Vaccine. 2005 Sep 27; [Epub ahead of print].
Rauter C, Mueller M, Diterich I, Zeller S, Hassler D, Meergans T, et al. Critical evaluation of urine-based PCR assay for diagnosis of Lyme borreliosis. Clin Diagn Lab Immunol. 2005;12(8):910-917.
Scheckelhoff MR, Telford SR, Hu LT. Protective efficacy of an oral vaccine to reduce carriage of Borrelia burgdorferi (strain N40) in mouse and tick reservoirs. Vaccine. 2005 Nov 4; [Epub ahead of print].
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital
