Borreliosis is an infectious disease caused by bacteria of the Borrelia type. The most common sign of infection is an expanding area of redness, known as erythema migrans, that begins at the site of a tick bite about a week after it has occurred. The rash is typically neither itchy nor painful. About 25% of people do not develop a rash. Other early symptoms may include fever, headache, and feeling tired. If untreated, symptoms may include loss of the ability to move one or both sides of the face, joint pains, severe headaches with neck stiffness, or heart palpitations, among others. Months to years later, repeated episodes of joint pain and swelling may occur. Occasionally, people develop shooting pains or tingling in their arms and legs. Despite appropriate treatment, about 10 to 20% of people also develop joint pains, have memory problems, and feel tired much of the time.
Borreliosis can affect multiple body systems and produce a broad range of symptoms. Not all patients with Lyme disease have all symptoms, and many of the symptoms are not specific to Lyme disease, but can occur with other diseases, as well. The incubation period from infection to the onset of symptoms is usually one to two weeks, but can be much shorter (days), or much longer (months to years).
Symptoms most often occur from May to September, because the nymphal stage of the tick is responsible for most cases. Asymptomatic infection exists, but occurs in less than 7% of infected individuals in the United States. Asymptomatic infection may be much more common among those infected in Europe.
Early localized infection
Early localized infection can occur when the infection has not yet spread throughout the body. Only the site where the infection has first come into contact with the skin is affected. The classic sign of early local infection with Lyme disease is a circular, outwardly expanding rash called erythema chronicum migrans (EM), which occurs at the site of the tick bite three to 32 days after the tick bite. The rash is red, and may be warm, but is generally painless. Classically, the innermost portion remains dark red and becomes indurated (is thicker and firmer), the outer edge remains red, and the portion in between clears, giving the appearance of a bull's eye. However, partial clearing is uncommon, and the bull's-eye pattern more often involves central redness.
The EM rash associated with early infection is found in about 80% of patients and can have a range of appearances including the classic target bull's-eye lesion and nontarget appearing lesions. The 20% without the EM and the nontarget lesions can often cause misidentification of Lyme disease. Affected individuals can also experience flu-like symptoms, such as headache, muscle soreness, fever, and malaise. Lyme disease can progress to later stages even in patients who do not develop a rash.
Early dissemanited infection
Within days to weeks after the onset of local infection, the Borrelia bacteria may begin to spread through the bloodstream. EM may develop at sites across the body that bear no relation to the original tick bite. Another skin condition, apparently absent in North American patients, but found in Europe, is borrelial lymphocytoma, a purplish lump that develops on the ear lobe, nipple, or scrotum. Other discrete symptoms include migrating pain in muscles, joints, and tendons, and dizziness.
Various acute neurological problems, termed neuroborreliosis, appear in 10–15% of untreated patients. These include facial palsy, which is the loss of muscle tone on one or both sides of the face, as well as meningitis, which involves severe headaches, neck stiffness, and sensitivity to light. Inflammation of the spinal cord's nerve roots can cause shooting pains that may interfere with sleep, as well as abnormal skin sensations. Mild encephalitis may lead to memory loss, sleep disturbances, or mood changes. In addition, some case reports have described altered mental status as the only symptom seen in a few cases of early neuroborreliosis. The disease may adversely impact the heart's electrical conduction system and can cause abnormal heart rhythms such as atrioventricular block.
Late dissemanited infection
After several months, untreated or inadequately treated patients may go on to develop severe and chronic symptoms that affect many parts of the body, including the brain, nerves, eyes, joints, and heart. Many disabling symptoms can occur, including permanent impairment of motor or sensory function of the lower extremities in extreme cases. The associated nerve pain radiating out from the spine is termed Bannwarth syndrome, named after Alfred Bannwarth.
The late disseminated stage is where the infection has fully spread throughout the body. Chronic neurologic symptoms occur in up to 5% of untreated patients. A polyneuropathy that involves shooting pains, numbness, and tingling in the hands or feet may develop. A neurologic syndrome called Lyme encephalopathy is associated with subtle cognitive difficulties, insomnia, a general sense of feeling unwell, and changes in personality. Other problems, however, such as depression and fibromyalgia, are no more common in people with Lyme disease than in the general population.
Chronic encephalomyelitis, which may be progressive, can involve cognitive impairment, brain fog, migraines, balance issues weakness in the legs, awkward gait, facial palsy, bladder problems, vertigo, and back pain. In rare cases, untreated Lyme disease may cause frank psychosis, which has been misdiagnosed as schizophrenia or bipolar disorder. Panic attacks and anxiety can occur; also, delusional behavior may be seen, including somatoform delusions, sometimes accompanied by a depersonalization or derealization syndrome, where the patients begin to feel detached from themselves or from reality.
Lyme arthritis usually affects the knees. In a minority of patients, arthritis can occur in other joints, including the ankles, elbows, wrists, hips, and shoulders. Pain is often mild or moderate, usually with swelling at the involved joint. Baker's cysts may form and rupture. In some cases, joint erosion occurs.
Acrodermatitis chronica atrophicans (ACA) is a chronic skin disorder observed primarily in Europe among the elderly. ACA begins as a reddish-blue patch of discolored skin, often on the backs of the hands or feet. The lesion slowly atrophies over several weeks or months, with the skin becoming first thin and wrinkled and then, if untreated, completely dry and hairless.
Lyme disease is caused by spirochetal bacteria from the genus Borrelia. Spirochetes are surrounded by peptidoglycan and flagella, along with an outer membrane similar to other Gram-negative bacteria. Because of their double-membrane envelope, Borrelia bacteria are often mistakenly described as Gram negative despite the considerable differences in their envelope components from Gram-negative bacteria. The Lyme-related Borrelia species are collectively known as Borrelia burgdorferi sensu lato, and show a great deal of genetic diversity.
B. burgdorferi sensu lato is made up of 18 closely related species, but only three clearly cause Lyme disease: B. burgdorferi sensu stricto (predominant in North America, but also present in Europe), B. afzelii, and B. garinii (both predominant in Eurasia). Some studies have also proposed B. bissettii and B. valaisiana may sometimes infect humans, but these species do not seem to be important causes of disease.
Lyme disease is classified as a zoonosis, as it is transmitted to humans from a natural reservoir among rodents by ticks that feed on both sets of hosts. Hard-bodied ticks of the genus Ixodes are the main vectors of Lyme disease (also the vector for Babesia). Most infections are caused by ticks in the nymphal stage, as they are very small and may feed for long periods of time undetected. Larval ticks are very rarely infected. Although deer are the preferred hosts of deer ticks, and the size of the tick population parallels that of the deer population, ticks cannot acquire Lyme disease spirochetes from deer. Rather, deer ticks acquire Borrelia microbes from infected rodents, such as the white-footed mouse, Peromyscus leucopus.
Within the tick midgut, the Borrelia's outer surface protein A (OspA) binds to the tick receptor for OspA, known as TROSPA. When the tick feeds, the Borrelia downregulates OspA and upregulates OspC, another surface protein. After the bacteria migrate from the midgut to the salivary glands, OspC binds to Salp15, a tick salivary protein that appears to have immunosuppressive effects that enhance infection. Successful infection of the mammalian host depends on bacterial expression of OspC.
Tick bites often go unnoticed because of the small size of the tick in its nymphal stage, as well as tick secretions that prevent the host from feeling any itch or pain from the bite. However, transmission is quite rare, with only about 1% of recognized tick bites resulting in Lyme disease. Transmission may occur within 24 hours of the tick bite.
In Europe, the vector is Ixodes ricinus, which is also called the sheep tick or castor bean tick. In China, Ixodes persulcatus (the taiga tick) is probably the most important vector. In North America, the black-legged tick or deer tick (Ixodes scapularis) is the main vector on the East Coast.
The lone star tick (Amblyomma americanum), which is found throughout the Southeastern United States as far west as Texas, is unlikely to transmit the Lyme disease spirochetes, though it may be implicated in a related syndrome called southern tick-associated rash illness, which resembles a mild form of Lyme disease.
On the West Coast of the United States, the main vector is the western black-legged tick (Ixodes pacificus). The tendency of this tick species to feed predominantly on host species such as lizards that are resistant to Borrelia infection appears to diminish transmission of Lyme disease in the West.
Transmission across the placenta during pregnancy has not been demonstrated, and no consistent pattern of teratogenicity or specific "congenital Lyme borreliosis" has been identified. As with a number of other spirochetal diseases, adverse pregnancy outcomes are possible with untreated infection; prompt treatment with antibiotics reduces or eliminates this risk.
While Lyme spirochetes have been found in insects, as well as ticks, reports of actual infectious transmission appear to be rare.Lyme spirochete DNA has been found in semen and breast milk, but transmission has not been known to take place through sexual contact. According to the CDC, live spirochetes have not been found in breast milk, urine, or semen. However, more recent studies published in 2014, suggest a link might exist.
Ticks that transmit B. burgdorferi to humans can also carry and transmit several other parasites, such as Theileria microti and Anaplasma phagocytophilum, which cause the diseases babesiosis and human granulocytic anaplasmosis (HGA), respectively. Among early Lyme disease patients, depending on their location, 2–12% will also have HGA and 2–40% will have babesiosis. Ticks in certain regions, including the lands along the eastern Baltic Sea, also transmit tick-borne encephalitis.
Coinfections complicate Lyme symptoms, especially diagnosis and treatment. It is possible for a tick to carry and transmit one of the coinfections and not Borrelia, making diagnosis difficult and often elusive. The Centers for Disease Control studied 100 ticks in rural New Jersey, and found 55% of the ticks were infected with at least one of the pathogens.
Protective clothing includes a hat, long-sleeved shirt, and long trousers tucked into socks or boots. Light-colored clothing makes the tick more easily visible before it attaches itself. People should use special care in handling and allowing outdoor pets inside homes because they can bring ticks into the house.
Permethrin sprayed on clothing kills ticks on contact, and is sold for this purpose. Insect repellents with Picaridin, IR3535, DEET, or oil of lemon eucalyptus repel ticks, as well.
A community can reduce the incidence of Lyme disease by reducing the numbers of primary hosts on which the deer tick depends, such as rodents, other small mammals, and deer. Reduction of the deer population may, over time, help break the reproductive cycle of the deer ticks and their ability to flourish in suburban and rural areas.
Management of host animals
Lyme and all other deer tick-borne diseases can be prevented on a regional level by reducing the deer population on which the ticks depend for reproductive success. (Although deer ticks do acquire Lyme disease pathogens from rodents and not from deer, the size of the tick population tends to parallel that of the deer population.) This has been demonstrated in the communities of Monhegan, Maine and Mumford Cove, Connecticut.
For example, in the U.S., reducing the deer population to levels of 8 to 10 per square mile (from the current levels of 60 or more deer per square mile in the areas of the country with the highest Lyme disease rates), the tick numbers can be brought down to levels too low to spread Lyme and other tick-borne diseases. However, such a drastic reduction may be impractical in many areas. Routine veterinary control of ticks of domestic animals, including livestock, by use of chemical acaricides can contribute to reducing exposure of humans to ticks. However, the risk of acquiring Lyme disease does not depend on the existence of a local deer population, as is commonly assumed. Eliminating deer from smaller areas 2.5 ha (6.2 acres) may in fact lead to an increase in tick density and the rise of "tick-borne disease hotspots".
Action can be taken to avoid getting bitten by ticks by using insect repellants, for example those that contain DEET. DEET-containing repellants are thought to be moderately effective in the prevention of tick bites.
In Europe known reservoirs of Borrelia burgdorferi were 9 small mammals, 7 medium-sized mammals and 16 species of birds (including passerines, sea-birds and pheasants). These animals seem to transmit spirochetes to ticks and thus participate in the natural circulation of B. burgdorferi in Europe. The house mouse is also suspected as well as other species of small rodents, particularly in Eastern Europe and Russia.
"The reservoir species that contain the most pathogens are the European roe deer Capreolus capreolus;"it does not appear to serve as a major reservoir of B. burgdorferi" thought Jaenson & al. (incompetent host for B. burgdorferi and TBE virus) but it is important for feeding the ticks, as red deer and wild boars (Sus scrofa), in which one Rickettsia and three Borrelia species were identified", with high risks of coinfection in roe deer. Nevertheless, in the 2000s, in roe deer in Europe " two species of Rickettsia and two species of Borrelia were identified.
A recombinant vaccine against Lyme disease, based on the outer surface protein A (ospA) of B. burgdorferi, was developed by SmithKline Beecham. In clinical trials involving more than 10,000 people, the vaccine, called LYMErix, was found to confer protective immunity to Borrelia in 76% of adults and 100% of children with only mild or moderate and transient adverse effects. LYMErix was approved on the basis of these trials by the Food and Drug Administration (FDA) on December 21, 1998.
Following approval of the vaccine, its entry in clinical practice was slow for a variety of reasons, including its cost, which was often not reimbursed by insurance companies. Subsequently, hundreds of vaccine recipients reported they had developed autoimmune side effects. Supported by some patient advocacy groups, a number of class-action lawsuits were filed against GlaxoSmithKline, alleging the vaccine had caused these health problems. These claims were investigated by the FDA and the Centers for Disease Control, which found no connection between the vaccine and the autoimmune complaints.
Despite the lack of evidence that the complaints were caused by the vaccine, sales plummeted and LYMErix was withdrawn from the U.S. market by GlaxoSmithKline in February 2002, in the setting of negative media coverage and fears of vaccine side effects. The fate of LYMErix was described in the medical literature as a "cautionary tale"; an editorial in Nature cited the withdrawal of LYMErix as an instance in which "unfounded public fears place pressures on vaccine developers that go beyond reasonable safety considerations." The original developer of the OspA vaccine at the Max Planck Institute told Nature: "This just shows how irrational the world can be... There was no scientific justification for the first OspA vaccine LYMErix being pulled."
New vaccines are being researched using outer surface protein C (OspC) and glycolipoprotein as methods of immunization. Vaccines have been formulated and approved for prevention of Lyme disease in dogs. Currently, three Lyme disease vaccines are available. LymeVax, formulated by Fort Dodge Laboratories, contains intact dead spirochetes which expose the host to the organism. Galaxy Lyme, Intervet-Schering-Plough's vaccine, targets proteins OspC and OspA. The OspC antibodies kill any of the bacteria that have not been killed by the OspA antibodies. Canine Recombinant Lyme, formulated by Merial, generates antibodies against the OspA protein so a tick feeding on a vaccinated dog draws in blood full of anti-OspA antibodies, which kill the spirochetes in the tick's gut before they are transmitted to the dog.
Attached ticks should be removed promptly, as removal within 36 hours can reduce transmission rates. Folk remedies for tick removal tend to be ineffective, offer no advantages in preventing the transfer of disease, and may increase the risks of transmission or infection. The best method is simply to pull the tick out with tweezers as close to the skin as possible, without twisting, and avoiding crushing the body of the tick or removing the head from the tick's body. The risk of infection increases with the time the tick is attached, and if a tick is attached for less than 24 hours, infection is unlikely. However, since these ticks are very small, especially in the nymph stage, prompt detection is quite difficult. The Australian Society of Clinical Immunology recommends against using tweezers to remove ticks but rather to kill the tick first by using a product to rapidly freeze the tick to prevent it from injecting more allergen-containing saliva. In a tick allergic person, the tick should be killed and removed in a safe place (e.g. an emergency department of a hospital).
The risk of infectious transmission increases with the duration of tick attachment. It requires between 36 and 48 hours of attachment for the bacteria that causes Lyme to travel from within the tick into its saliva. If a deer tick that is sufficiently likely to be carrying Borrelia is found attached to a person and removed, and if the tick has been attached for 36 hours or is engorged, a single dose of doxycycline administered within the 72 hours after removal may reduce the risk of Lyme disease. It is not generally recommended as development of infection is rare: about 50 people would have to be treated this way to prevent one case of infection.
Lyme disease is diagnosed clinically based on symptoms, objective physical findings (such as EM, facial palsy, or arthritis), or a history of possible exposure to infected ticks, as well as serological blood tests. The EM rash is not always a bull's eye, i.e., it can be solid red. When making a diagnosis of Lyme disease, health care providers should consider other diseases that may cause similar illnesses. Not all patients infected with Lyme disease develop the characteristic bull's-eye rash, and many may not recall a tick bite.
Because of the difficulty in culturing Borrelia bacteria in the laboratory, diagnosis of Lyme disease is typically based on the clinical exam findings and a history of exposure to endemic Lyme areas. The EM rash, which does not occur in all cases, is considered sufficient to establish a diagnosis of Lyme disease even when serologic blood tests are negative. Serological testing can be used to support a clinically suspected case, but is not diagnostic by itself.
Diagnosis of late-stage Lyme disease is often complicated by a multifaceted appearance and nonspecific symptoms, prompting one reviewer to call Lyme the new "great imitator". Lyme disease may be misdiagnosed as multiple sclerosis, rheumatoid arthritis, fibromyalgia, chronic fatigue syndrome, lupus, Crohn's disease, HIV, or other autoimmune and neurodegenerative diseases. As all patients with later-stage infection will have a positive antibody test, simple blood tests can exclude Lyme disease as a possible cause of the patients' symptoms.
Several forms of laboratory testing for Lyme disease are available, some of which have not been adequately validated. The most widely used tests are serologies, which measure levels of specific antibodies in a patient's blood. These tests may be negative in early infection, as the body may not have produced a significant quantity of antibodies, but they are considered a reliable aid in the diagnosis of later stages of Lyme disease. Serologic tests for Lyme disease are of limited use in people lacking objective signs of Lyme disease because of false positive results and cost.
The serological laboratory tests most widely available and employed are the Western blot and ELISA. A two-tiered protocol is recommended by the Centers for Disease Control and Prevention: the sensitive ELISA test is performed first, and if it is positive or equivocal, then the more specific Western blot is run. The reliability of testing in diagnosis remains controversial. Studies show the Western blot IgM has a specificity of 94–96% for patients with clinical symptoms of early Lyme disease. The initial ELISA test has a sensitivity of about 70%, and in two-tiered testing, the overall sensitivity is only 64%, although this rises to 100% in the subset of people with disseminated symptoms, such as arthritis.
Erroneous test results have been widely reported in both early and late stages of the disease, and can be caused by several factors, including antibody cross-reactions from other infections, including Epstein-Barr virus and cytomegalovirus, as well as herpes simplex virus. The overall rate of false positives is low, only about 1 to 3%, in comparison to a false-negative rate of up to 36% in the early stages of infection using two-tiered testing.
Polymerase chain reaction (PCR) tests for Lyme disease have also been developed to detect the genetic material (DNA) of the Lyme disease spirochete. PCR tests are susceptible to false positive results from poor laboratory technique. Even when properly performed, PCR often shows false negative results with blood and cerebrospinal fluid specimens. Hence, PCR is not widely performed for diagnosis of Lyme disease, but it may have a role in diagnosis of Lyme arthritis, because it is a highly sensitive way of detecting ospA DNA in synovial fluid.
With the exception of culture or PCR, no practical means for detecting the presence of the organism is currently available, as serologic studies only test for antibodies of Borrelia. High titers of either immunoglobulin G (IgG) or immunoglobulin M (IgM) antibodies to Borrelia antigens indicate disease, but lower titers can be misleading, because the IgM antibodies may remain after the initial infection, and IgG antibodies may remain for years.
Western blot, ELISA, and PCR can be performed by either blood test via venipuncture or cerebrospinal fluid (CSF) via lumbar puncture. Though lumbar puncture is more definitive of diagnosis, antigen capture in the CSF is much more elusive; reportedly, CSF yields positive results in only 10–30% of patients cultured. The diagnosis of neurologic infection by Borrelia should not be excluded solely on the basis of normal routine CSF or negative CSF antibody analyses.
New techniques for clinical testing of Borrelia infection have been developed, such as LTT-MELISA, although the results of studies are contradictory, The first peer reviewed study assessing the diagnostic sensitivity and specificity of the test has been presented in 2012, showing potential for LTT to become a supportive diagnostic tool. In 2014, research of LTT-MELISA concluded that it is "sensible" to include the LTT test in the diagnostic protocol for putative European-acquired Lyme borreliosis infections. Others, such as focus floating microscopy, are under investigation. New research indicates chemokine CXCL13 may also be a possible marker for neuroborreliosis.
Some laboratories offer Lyme disease testing using assays whose accuracy and clinical usefulness have not been adequately established. These tests include urine antigen tests, PCR tests on urine, immunofluorescent staining for cell wall-deficient forms of B. burgdorferi, and lymphocyte transformation tests. The CDC does not recommend these tests, and stated their use is "of great concern and is strongly discouraged".
Neuroimaging is controversial in whether it provides specific patterns unique to neuroborreliosis, but may aid in differential diagnosis and in understanding the pathophysiology of the disease. Though controversial, some evidence shows certain neuroimaging tests can provide data that are helpful in the diagnosis of a patient. Magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT) are two of the tests that can identify abnormalities in the brain of a patient affected with this disease. Neuroimaging findings in an MRI include lesions in the periventricular white matter, as well as enlarged ventricles and cortical atrophy. The findings are considered somewhat unexceptional because the lesions have been found to be reversible following antibiotic treatment. Images produced using SPECT show numerous areas where an insufficient amount of blood is being delivered the cortex and subcortical white matter. However, SPECT images are known to be not specific because they show a heterogeneous pattern in the imaging. The abnormalities seen in the SPECT images are very similar to those seen in patients with cerebral vacuities and Creutzfeldt-Jakob disease, which makes them questionable.
For early cases, prompt[Specific Time?] treatment is usually curative. However, the severity and treatment of Lyme disease may be complicated due to late diagnosis, failure of antibiotic treatment, and simultaneous infection with other tick-borne diseases (coinfections), including ehrlichiosis, babesiosis, and immune suppression in the patient.
A meta-analysis published in 2005 found some patients with Lyme disease have fatigue, joint or muscle pain, and neurocognitive symptoms persisting for years, despite antibiotic treatment. Patients with late stage Lyme disease have been shown to experience a level of physical disability equivalent to that seen in congestive heart failure.
In dogs, a serious long-term prognosis may result in glomerular disease, which is a category of kidney damage that may cause chronic kidney disease. Dogs may also experience chronic joint disease if the disease is left untreated. However, the majority of cases of Lyme disease in dogs result in a complete recovery with, and sometimes without, treatment with antibiotics. In rare cases, Lyme disease can be fatal to both humans and dogs
Antibiotics are the primary treatment. The specific approach to their use is dependent on the individual affected and the stage of the disease. For most people with early localized infection, oral administration of doxycycline is widely recommended as the first choice, as it is effective against not only Borrelia bacteria but also a variety of other illnesses carried by ticks. Doxycycline is contraindicated in children younger than eight years of age and women who are pregnant or breastfeeding; alternatives to doxycycline are amoxicillin, cefuroxime axetil, and azithromycin. Individuals with early disseminated or late infection may have symptomatic cardiac disease, refractory Lyme arthritis, or neurologic symptoms like meningitis or encephalitis. Intravenous administration of ceftriaxone is recommended as the first choice in these cases; cefotaxime and doxycycline are available as alternatives.
These treatment regimens last from one to four weeks. If joint swelling persists or returns, a second round of antibiotics may be considered. Outside of that, a prolonged antibiotic regimen lasting more than 28 days is not recommended as no clinical evidence shows it to be effective. IgM and IgG antibody levels may be elevated for years even after successful treatment with antibiotics. As antibody levels are not indicative of treatment success, testing for them is not recommended.