Lyme disease

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Lyme disease
Classification & external resources

Nymphal and adult deer ticks can be carriers of Lyme disease. Nymphs are about the size of a poppy seed.
ICD-10	A69.2
ICD-9	088.81
DiseasesDB	1531
MedlinePlus	001319
eMedicine	med/1346

Lyme disease is a bacterial infection with a spirochete from the species complex Borrelia burgdorferi sensu lato, which is most often acquired from the bite of an infected Ixodes tick. Borrelia burgdorferi sensu stricto is the predominant cause of Lyme disease in the U.S.; Lyme disease in Europe is more often caused by Borrelia afzelii or Borrelia garinii.

The disease varies widely in its presentation, which may include a rash and flu-like symptoms in its initial stage, followed by the possibility of musculoskeletal, arthritic, neurologic, psychiatric and cardiac manifestations. Most cases of Lyme disease can be cured with antibiotics, especially if treatment is begun early in the course of illness.

A percentage of patients with Lyme disease have symptoms that last months to years after treatment with antibiotics. These symptoms can include muscle and joint pains, arthritis, cognitive defects, neurological complaints or fatigue. The cause of these continuing symptoms is not yet known. There is some evidence that they may result from an autoimmune type of response, in which a person’s immune system continues to respond even after the infection has been cleared, or may be from ongoing spirochete infection. Further investigation into late stage or chronic Lyme will hopefully elucidate this answer.

Contents 1 History 2 Microbiology 3 Transmission 3.1 By ticks 3.2 Congenital 3.3 Other 4 Ecology 5 Epidemiology 6 Prevention 6.1 Vaccination 6.2 Removal of ticks 7 Symptoms 7.1 Acute (early) symptoms 7.2 Late stage symptoms 8 Diagnosis 8.1 Diagnosis of Late Stage Lyme Disease 9 Treatment 9.1 Antibiotic Treatment Controversy 9.2 Alternative Therapies 10 Prognosis 11 Controversy 12 Advancing Immunology Research 13 References 14 External links

[edit] History

The name of the disease comes from its epidemiological epicenter, the town of Lyme, Connecticut where a cluster of cases was identified in 1976. Although clinical features of the disease had been described as early as the beginning of the 20th century, the disease in its modern form gets it root from the cases in Lyme, Connecticut.^[1]

The first record of a condition associated with Lyme disease dates back to 1883 in Breslau, Germany, where a physician named Alfred Buchwald described a degenerative skin disorder now known as acrodermatitis chronica atrophicans. In a 1909 meeting of the Swedish Society of Dermatology, Arvid Afzelius presented research about an expanding, ring like lesion he had observed. Afzelius published his work 12 years later and speculated that the rash came from the bite of an Ixodes tick, meningitic symptoms and signs in a number of cases and that both sexes were affected. This rash is now known as erythema migrans, the skin rash found in early stage Lyme disease.^[2]

In the 1920s, French physicians Garin and Bujadoux described a patient with meningoencephalitis, painful sensory radiculitis, and erythema migrans following a tick bite, and they postulated the symptoms were due to a spirochetal infection. In the 1940s, German neurologist Alfred Bannwarth described several cases of chronic lymphocytic meningitis and polyradiculoneuritis, some of which were accompanied by erythematous skin lesions.

Interest in tick-borne infections in the U.S. began with the first report of tick-borne relapsing fever (borrelia hermsii) in 1915, following the recognition of five human patients in Colorado.^[3] The discovery of the wood tick's role as a vector of Rocky Mountain spotted fever was not made until later. The full syndrome now known as Lyme disease was not recognized until a cluster of cases originally thought to be juvenile rheumatoid arthritis was identified in three towns in southeastern Connecticut in 1976. Two of these towns, Lyme and Old Lyme, gave the disease its popular name. ^[4]

Before 1976, elements of Borrelia infection were called or known as Tickborne meningopolyneuritis, Garin-Bujadoux syndrome, Bannworth syndrome, Afzelius syndrome, or sheep tick fever.

In 1982 a novel spirochete was isolated and cultured from the midgut of Ixodes ticks in Shelter Island, New York, and subsequently from patients with Lyme disease. The infecting agent was then identified by Jorge Benach, and soon after isolated by Willy Burgdorfer, a scientist at the National Institutes of Health, who specialized in the study of spirochete microorganisms. The spirochete was named Borrelia burgdorferi in his honor. Burgdorfer was the partner in the successful effort to culture the spirochete, along with Alan Barbour.

After the isolation of the spirochete from the midgut of Ixodes ticks, how ticks actually transmitted this new pathogen was the subject of much discussion. The hypothesis that Lyme disease spirochetes were transmitted via the salivary gland route of Ixodes ticks was confirmed when spirochetes were actually identified in tick saliva in 1987.^[5]

[edit] Microbiology

Main article: Lyme disease microbiology

Lyme disease is caused by spirochetal bacteria from the genus Borrelia, which has well over three hundred known genomic strains. The Borrelia species known to cause Lyme disease are collectively known as Borrelia burgdorferi sensu lato, and have been found to have greater strain diversity than previously estimated.^[6]

Until recently it was thought that only three genospecies caused Lyme disease: B. burgdorferi sensu stricto (predominant in North America, but also in Europe), B. afzelii, and B. garinii (both predominant in Eurasia). However, newly discovered genospecies have also been found to cause disease in humans.

Borrelia is a gram negative bacterium. Chemical analysis of the external membrane of B. burgdorferi revealed the presence of 46% proteins, 51% lipids and 3% carbohydrates. ^[7]

[edit] Transmission

[edit] By ticks

Hard-bodied (Ixodes) ticks are the primary Lyme disease vectors. In Europe, Ixodes ricinus, known commonly as the sheep tick, castor bean tick, or European castor bean tick is the transmitter. In North America, Ixodes scapularis (black-legged tick or deer tick) has been identified as the key to the disease's spread on the east coast, while on the west coast the primary vector is Ixodes pacificus (Western black-legged tick). A CDC-published map showing the relative risk of Lyme disease infection by region can be found here.

Another possible vector is Amblyomma americanum (Lone Star tick),^[8] which is found throughout the southeastern U.S. as far west as Texas, and increasingly in northeastern states as well.

It is believed that the longer the duration of tick attachment, the greater the risk of disease transmission; typically, for the spirochete to be transferred, the tick must be attached for a minimum of 12 hours, although, only the first part of this statement can be said to be strictly correct. (See Removal of ticks.)

Unfortunately only 20% of persons infected with Lyme by the deer tick are aware of any tick bite,^[9] making early detection difficult in the absence of a rash. Tick bites usually go unnoticed due to 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.

New research suggests that transmission can occur within a few hours of tick attachment, and that the rate of transmission by infected ticks may be much higher than previously assumed.^{[citation needed]}

[edit] Congenital

Lyme disease can be transmitted from an infected mother to fetus through the placenta during pregnancy, possibly resulting in stillbirth.^[10][11] The risk of transmission is minimized if the mother receives prompt antibiotic treatment,^{[citation needed]} though physicians disagree as to the duration of treatment required.^{[citation needed]}

[edit] Other

There is at least one case report of transmission by a biting fly.^[12] Lyme spirochetes have been found in biting flies as well as mosquitos.^[13] Some researchers believe biting insects do not feed long enough to transmit the infection, while others including Borrelia burgdorferi discoverer Willy Burgdorfer believe more research is needed.^[14] Sexual transmission has been anecdotally reported; Lyme spirochetes have been found in semen^[15] and breast milk,^[16] however sexual transmission of the spirochete by these routes is not known to occur.^[17]

[edit] Ecology

Urbanization and other anthropogenic factors can be implicated in the spread of the Lyme disease into the human population. In many areas, expansion of suburban neighborhoods has led to the gradual deforestation of surrounding wooded areas and increasing "border" contact between humans and tick-dense areas. Human expansion has also resulted in a gradual reduction of the predators that normally hunt deer as well as mice, chipmunks and other small rodents--the primary reservoirs for Lyme disease. As a consequence of increased human contact with host and vector, the likelihood of transmission to Lyme residents has greatly increased.^[18][19] Researchers are also investigating possible links between global warming and the spread of vector-borne diseases including Lyme disease.^[20]

The deer tick (Ixodes scapularis, the primary vector in the northeastern U.S.) has a two-year life cycle, first progressing from larva to nymph, and then from nymph to adult. The tick feeds only once at each stage. In the fall, large acorn forests attract deer as well as mice, chipmunks and other small rodents infected with B. burgdorferi. During the following spring, the ticks lay their eggs. The rodent population then "booms." Tick eggs hatch into larvae, which feed on the rodents; thus the larvae acquire infection from the rodents. (Note: At this stage, it is proposed that tick infestation may be controlled using acaricides (miticide).

Adult ticks may also transmit disease to humans. After feeding, female adult ticks lay their eggs on the ground, and the cycle is complete. Note: on the west coast, Lyme disease is spread by the western black-legged tick (Ixodes pacificus), which has a different life cycle.

The risk of acquiring Lyme disease does not depend on the existence of a local deer population, as is commonly assumed. New research suggests that eliminating deer from smaller areas (less than 2.5 ha or 6.2 acres) may in fact lead to an increase in tick density and the rise of "tick-borne disease hotspots".^[21]

[edit] Epidemiology

Lyme disease is the most common tick-borne disease in North America and Europe, and one the fastest-growing infectious disease in the United States. Of cases reported to the United States Center for Disease Control (CDC), the ratio of Lyme disease infection is 7.9 cases for every 100,000 persons. In the ten states where Lyme disease is most common, the average was 31.6 cases for every 100,000 persons for the year 2005^[22]

Although Lyme disease has now been reported in 49 of 50 states in the U.S, about 99% of all reported cases are confined to just five geographic areas (New England, Mid-Atlantic, East-North Central, South Atlantic, and West North-Central).

The number of reported cases of the disease have been increasing, as are endemic regions in North America. For example, it had previously been thought that Borrelia burgdorferi couldn't be maintained in an enzootic cycle in California because it was assumed the large lizard population would dilute the prevalence of Borrelia burgdorferi in local tick poplations, but this has since been proven false as lizards are now known carriers of ticks in North America, Europe and North Africa.

Whereas Borrelia Burgdoferi is most associated with deer tick and the white tailed mouse, Borrelia afzelii is most frequently detected in rodent-feeding vector ticks, Borrelia garinii and Borrelia valaisiana appear to be associated with birds. Both rodents and birds are competent reservoir hosts for Borrelia burgdorferi sensu stricto. The resistance of a genospecies of Lyme disease spirochetes to the bacteriolytic activities of the alternative complement pathway of various host species may determine its reservoir host association.

In Europe, cases of borrelia infected ticks are found predominantly in the Netherlands, Germany, France, Norway, Italy, Slovenia and Poland, but have been isolated in almost every country on the continent.

In South America tick borne disease recognition and occurrence is rising. Ticks carrying borrelia, as well as canine and human tick-borne disease, has been reported widely in Brazil, but the subspecies of borrelia has not yet been defined.^[23] The first reported case of Lyme Disease in Brazil was made in 1993 in Sao Paulo.^[24] Borrelia burgdorferi sensu stricto antigens in patients have been identified in Colombia and in Bolivia.

Borrelia infested ticks are being found more frequently in Japan, as well as in Northwest China and far eastern Russia.^[25][26] Borrelia has been isolated in Mongolia as well.^[27]

In Northern Africa borrelia has been identified in Morroco, Algeria, Egypt and Tunisia.^[28][29][30]

In Western and Sub-Saharan Africa, tick-borne relapsing fever has been recognized for over a century, first isolated by the British physicians Joseph Dutton and John Todd in 1905. Borrelia in the manifestation of Lyme disease in this region is presently unknown but evidence indicates that the disease may occur in humans in sub-Saharan Africa. The abundance of hosts and tick vectors would favor the establishment of the infection in Africa.^[31]

[edit] Prevention

The best prevention involves avoiding areas in which ticks are found and can reduce the probability of contracting Lyme disease. Other good prevention practices include wearing clothing that covers the entire body when in a wooded area; using mosquito/tick repellent; after exposure to wooded areas, check all parts of the body (including hair) for ticks.

For clothing, you should wear long sleeve shirts and pants that are tucked into socks or boots. One should also wear light colored clothing so that you can see the tick on you before it attaches itself.

[edit] Vaccination

A vaccine against a North American strain of the spirochetal bacteria was available between 1998 and 2002 by GlaxoSmithKline (GSK) called Lymerix and was based on the outer surface protein A (Osp-A) of borrelia. Osp-A causes creation of antibodies from the body's immune system to attack that protein. When taking it off the market, GSK cited poor sales, need for frequent boosters, the high price of the vaccine, and exclusion of children. Some people believe that the actual reason was that the vaccine was neither safe nor effective. A group of patients whom took Lymerix developed arthritis, muscle pain and other troubling symptoms after vaccination. Class-action litigation against GSK followed. ^[32]

It was later learned that patients with the genetic allele HLA-DR4 were susceptible to T cell crossreactivity between epitopes of OspA and lymphocyte function-associated antigen in these patients causing an autoimmune reaction.^[33]

New vaccines are being researched using outer surface protein C (Osp-C) and glycolipoprotein as methods of immunization.^[34][35]

[edit] Removal of ticks

There are many urban legends about the proper and effective method to remove a tick. One legend states that something hot (cigarette; burnt match) should be applied to the back of the tick, which causes the tick to remove its head from the victim. It further states that ticks "screw" their heads into their victims; therefore, one must "unscrew" the head. These legends are incorrect and potentially dangerous because if a tick is disturbed it may regurgitate its stomach contents into the host including the agents of tick borne disease if the tick is infected.

Proper removal of a tick: use a pair of tweezers, grab the head of the tick near the mouth, and pull it straight out, no turning or twisting. The area should then be disinfected with rubbing alcohol or hydrogen peroxide. If the head is not completely removed, local infection of the person/animal bitten may result, and a doctor should be consulted (or a veterinarian if the tick was removed from a pet). It is important not to handle the tick with bare hands or let it crawl on you because simply touching a tick that has RMSF (Rocky Mountain Spotted Fever) may transmit that infection.^[36]

[edit] Symptoms

[edit] Acute (early) symptoms

Early symptoms of Lyme disease may be heterogeneous and nonspecific and include:

• Rash

Erythema migrans rash (EM) - Contrary to popular belief, the characteristic "bull's-eye" rash with central clearing is not the most common form. Rashes that are homogeneously red are seen more frequently.^[37][38] Multiple painless EM rashes may occur, indicating disseminated infection. The true incidence of the rash is disputed, with estimates ranging from less than 50%^[39][40] to over 80%^{[citation needed]} of those infected. EM may be less than 5 cm in diameter.^[41]

• fever
• malaise or fatigue
• headache
• sore throat
• muscle and joint aches
• Heart palpitations
• Tick paralysis

Kidney and intestinal pain may also occur. Early objective manifestations which may be present include meningitis, facial paralysis such as Bells palsy, and/or heart block.

The incubation period from infection to the onset of symptoms is usually 1–2 weeks, but can be much shorter (a couple of days), or even months to years. Asymptomatic infection exists, but the incidence of this is unknown.^{[citation needed]}

[edit] Late stage symptoms

Lyme disease in its tertiary form can have a multitude of symptoms. The symptoms appear heterogeneous in the infected population, which may be due to innate immunity or borrelia sub-species bacterium. The late symptoms of Lyme disease can appear months after initial infection and often progress in cumulative fashion over time. Neuro-psychiatric symptoms often develop much later in disease sequence, much like tertiary neurosyphilis.

Physical:

• fatigue
• muscle pain (myalgia)
• joint pain with or without frank arthritis
• rash
• cardiac arrhythmias
• tachycardia (too-rapid heartbeat)
• nausea or vomiting
• adrenal disorders
• immune suppression
• urinary disorder

Neurological:

• muscle twitching
• Bell's palsy
• encephalitis or encephalomyelitis
• vision problems (eg. double vision or intermediate uveitis)
• sensitivity to light, motion, or keratitis
• hyperacusis (severe sensitivity to sound & vibration)
• vestibular symptoms (balance disorder may be mediated by CNS or inner/middle ear) and other Otolaryngologic symptoms ^[42][43]
• nystagmus
• seizures
• myoclonus
• ataxia

Neuropsychiatric:

• panic attacks
• depression
• short-term memory loss
• sleep disturbance
• hallucinations
• depersonalization
• general cognitive impairment (brain fog)
• psychosis (rare) including diagnosis of schizophrenia and bipolar disorder^[44][45]

[edit] Diagnosis

The most reliable method of diagnosing Lyme disease is a clinical exam by an experienced practitioner, taking into account symptoms, history, and possible exposure to ticks in an endemic area. Clinicians who diagnose strictly based on the U.S. Centers for Disease Control (CDC) Case Definition for Lyme are in error, as the CDC explicitly states that this definition is intended for surveillance purposes only, and is "not intended to be used in clinical diagnosis."^[46][47]

The EM rash, which does not occur in all cases, is considered sufficient to make a diagnosis of Lyme disease and prompt treatment without further testing. In fact because of the undisputed high rate of false negatives during the early stage of the disease (before a sufficient antibody response has been established), it is recommended that tests not be performed when a patient has an EM rash.^[38][48][49]

The serological laboratory tests available are the Western blot and ELISA. In the two-tiered protocol recommended by the CDC according to their case definition, the ELISA is performed first, and if it is positive or equivocal, a Western blot is then performed to support the diagnosis. The reliability of testing in diagnosis remains controversial (see Lyme disease controversy#Testing). However studies show the Western blot IgM has a specificity of 94-96% for patients with symptoms suggestive of Lyme disease with infection by Borrelia burgoferi.^[50][51]

False-negative test results have been widely reported in both early and late disease. False Negatives can take place for a broad spectrum of reasons, including cross reaction of other infections such as^[52][53] cytomegalovirus.^[52] and herpes simplex type virus 2.^{[54][55][56][57][58][59]}

Polymerase chain reaction (PCR) tests for Lyme disease may also be available to the patient. A PCR test attempts to detect the genetic material (DNA) of the Lyme disease spirochete, whereas the Western blot and ELISA tests look for antibodies to the organism. PCR tests are rarely susceptible to false-positive results but can often show false-negative results. PCR reliability is still questioned.

With the exception of PCR testing, currently there is no practical means for detection of the presence of the organism, 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. The IgM antibodies may remain after the initial infection, and IgG antibodies may remain for years.^[60]

Western blot, ELISA and PCR can be performed by either blood test via venipuncture or cerebral spinal 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.^[61]

New tests being studied for commercial use include Lymphocyte transformation tests, aka LTT-MELISA(R) and focus floating microscopy (FFM) for borrelia hold more promise for unequivocal testing than the the standard commercial laboratory tests now available.

Skin biopsy can be used to confirm infection of borrelia but it usually reserved for research work and not used in the clinical setting.

[edit] Diagnosis of Late Stage Lyme Disease

In late stage Lyme disease it is often difficult to diagnose due to the multi-faceted appearance which can mimic symptoms of many ailments of better known diseases. For this reason Lyme has often been called the new "Great Imitator".^[62] Lyme disease may be misdiagnosed as multiple sclerosis, rheumatoid arthritis, fibromyalgia, chronic fatigue syndrome (CFS), or other autoimmune and neurodegenerative diseases, which leaves the infection untreated and allows it to disperse and invade various organs and tissue.

Some of these conditions may be misdiagnosed as Lyme disease, due to the wide range of symptoms found in Lyme disease, the questionable serology testing available, or due to physicians using Lyme disease as an explanation for an unknown malady.

SPECT imaging is often used to look for cerebral hypoperfusion indicative of Lyme encephalitis in the patient. SPECT is not a diagnostic tool in and of itself, but it a useful method of determining brain function.

In Lyme patients cerebral hypoperfusion of frontal subcortical and cortical structures is usually found.^[63] In about 70% of chronic Lyme disease patients with cogntive symptoms, brain SPECT scans typically reveal a pattern of global hypoperfusion in a heterogeneous distribution through the white matter.^[64] This pattern is not definite or specific for Lyme disease per se, as it can also be seen in other central nervous system (CNS) syndromes such as HIV encephalopathy, viral encephalopathy, chronic cocaine use, and vasculitides. The pattern found in Lyme patients is different from what one would see with normal controls or patients with depression or Alzheimer's.

[edit] Treatment

The mainstay of treatment for Lyme disease is antibiotics. Penicillin was first demonstrated by researchers to be useful against borrellia in the 1950's. Today the antibiotics of choice are doxycycline, amoxicillin and ceftriaxone. Macrolide antibiotics are also used.

• Doxycycline - bacteriostatic properties stops synthesis of bacteria replication.
• Amoxicillin - bactericidal properties kill bacterium, Beta-lactam properties inhibit the synthesis of bacterial cell walls.
• Ceftriaxone - (intravenous therapy) bactericidal properties kill bacterium. Has central nervous system penetration.

Persons who remove attached ticks should be monitored closely for signs and symptoms of tick-borne diseases for up to 30 days. A three day course of doxycycline therapy may be considered for deer tick bites when the tick has been on the person for at least 12 hours.^[65] Patients should be advised to report any Erythema migrans over the subsequent two to six weeks. If there should be suspicion of disease, then a course of Doxycycline should be immediately given for ten days; without awaiting serology tests which only yield positive results after an interval of one to two months.

Traditional treatment of acute Lyme disease usually consists of a minimum two-week to one-month course of antibiotics, either doxycycline 100-200mg or amoxicillin 1500-2000mg per day.

In later stages, the bacteria disseminate throughout the body and may cross the blood-brain barrier, making the infection more difficult to treat. Late diagnosed Lyme is treated with oral or IV antibiotics, frequently ceftriaxone, 2 grams per day, for a minimum of four weeks.

Lyme arthritis which is antibiotic resistant may be treated with hydroxychloroquine or methotrexate.^[66]

[edit] Antibiotic Treatment Controversy

Further information: Lyme disease controversy

With little research conducted specifically on treatment for late/chronic Lyme disease, treatment remains controversial. Currently there are two sets of peer-reviewed published guidelines; the International Lyme and Associated Diseases Society (ILADS)^[67] advocates extended courses of antibiotics for chronic Lyme patients in light of evidence of persistent infection, while the Infectious Diseases Society of America^[68] does not recognize chronic infection and recommends no treatment for persistent symptoms . Double-blind, placebo-controlled trials of long-term antibiotics for chronic Lyme have produced mixed results.

[edit] Alternative Therapies

A number of alternative therapies have been suggested, though clinical trials have not been conducted. For example, the use of hyperbaric oxygen therapy (which is used conventionally to treat a number of other conditions), as an adjunct to antibiotics for Lyme has been discussed.^[69] Though there are no published data from clinical trials to support its use, preliminary results using a murine model suggest its effectiveness against Borrelia burgdorferi both in vitro and in vivo.^[70]

Alternative medicine approaches include bee venom because it contains the peptide melittin, which has been shown to exert profound inhibitory effects on lyme bacteria in vitro.^[71] The herb andrographis, though not specifically studied for Borrelia species, has been found to have both antimalarial and antibacterial properties against a wide range of organisms in vitro and in vivo, leading some herbalists to recommend it for Lyme.^[72]

Anecdotal clinical research has shown potential for the antifungal azole medications such as diflucan in the treatment of Lyme, but has yet to be repeated in a controlled study or postulated a developed hypothetical model for its use.^[73]

[edit] Prognosis

For early cases, prompt treatment is usually curative.^[74] However, the severity and treatment of Lyme disease may be complicated due to late diagnosis, failure of antibiotic treatment, simultaneous infection with other tick-borne diseases including ehrlichiosis, babesiosis, and bartonella, and immune suppression in the patient (sometimes resulting from inappropriate treatment with steroids).

A meta-analysis published in 2005 found that some patients with Lyme disease have fatigue, joint and/or muscle pain, and neurocognitive symptoms persisting for years despite antibiotic treatment.^[75] Patients with Late Stage Lyme disease have been shown to experience a level of physical disability equivalent to that seen in congestive heart failure.^[76] The disease can be fatal in and of itself; deaths have been reported.^{[77][78][79][80][81]} The first CDC recognized death from Lyme disease was Amanda Schmidt, 11.^[82]

[edit] Controversy

Main article: Lyme disease controversy

There is no doubt that Lyme disease exists, and most clinicians agree on the treatment of early Lyme disease,^[83] there is considerable controversy as to the prevalence of the disease, the proper procedure for diagnosis and treatment of later stages, and the likelihood of a chronic, antibiotic-resistant Lyme infection. On one side are those who believe that Lyme disease is relatively rare, easily diagnosed with available blood tests, and easily treated with two to four weeks of antibiotics.^[84] On the other side are those who believe that Lyme disease is under-diagnosed, that available blood tests are unreliable, and that extended antibiotic treatment is often necessary.^{[85][86][87][88]}

The majority of public health agencies such as the U.S. Centers for Disease Control maintain the former position. While this narrower position is sometimes described as the "mainstream" view of Lyme disease, published studies involving non-randomized surveys of physicians in endemic areas found physicians evenly split in their views, with the majority recognizing seronegative Lyme disease, and roughly half prescribing extended courses of antibiotics for chronic Lyme disease.^[89][90]

Since October 2006, the Lyme controversy has heated up dramatically beginning with the release of updated diagnosis and treatment guidelines from the Infectious Diseases Society of America (IDSA).^[91] The new IDSA recommendations are even more restrictive than before, requiring either an EM rash or positive laboratory tests for diagnosis. Seronegative Lyme disease is no longer acknowledged, except in early Lyme. The authors of the guidelines maintain that chronic Lyme disease does not result from persistent infection, and therefore treatment beyond 2-4 weeks is not recommended by the IDSA, even in late stage cases.

[edit] Advancing Immunology Research

The role of T cells concomitant to borrelia was first made in 1984,^[92] the role of cellular immunity in active Lyme disease was made in 1986,^[93] and long term persistance of T cell lymphocyte responses to B. burgdorferi as an "immunological scar syndrome" was hypothesized in 1990.^[94] The role Th1 and interferon-gamma (INF-gamma) in borrelia was first described in 1995.^[95] The cytokine pattern of Lyme disease, and the role of Th1 with down regulation of interleukin-10 (IL-10) was first proposed in 1997.^[96]

Recent studies in both acute and antibiotic refractory, or chronic, Lyme disease have shown a distinct pro-inflammatory immune process. This pro-inflammatory process is a cell-mediated immunity and results in Th1 upregulation. These studies have shown a significant decrease in cytokine output of (IL-10), an upregulation of Interleukin-6 (IL-6) and IFN-gamma and disregulation in TNF-alpha predominantly.^[97]

These studies suggest that the host immune response to infection results in increased levels of IFN-gamma in the serum and lesions of Lyme disease patients that correlate with greater severity of disease. IFN-gamma alters gene expression by endothelia exposed to B. burgdorferi in a manner that promotes recruitment of T cells and suppresses that of neutrophils.

Studies also suggest suppressors of cytokine signaling (SOCS) proteins are induced by cytokines, and T cell receptor can down-regulate cytokine and T cell signaling in macrophages. It is hypothesized that SOCS are induced by IL-10 and Borellia burgdorferi and its lipoproteins in macrophages, and that SOCS may mediate the inhibition of IL-10 by concomitantly elicited cytokines. IL-10 is generally regarded as an anti-inflammatory cytokine, since it acts on a variety of cell types to suppress production of proinflammatory mediators.

Researchers are also beginning to identify microglia as a previously unappreciated source of inflammatory mediator production following infection with Borellia burgdorferi. Such production may play an important role during the development of cognitive disorders in Lyme neuroborreliosis. This effect is associated with induction of nuclear factor-kappa B (NF-KB) by borrelia.^{[98][99][100]}

Disregulated production of pro-inflammatory cytokines such as IL-6 and TNF-alpha can lead to neuronal damage in the borrelia infected patient.^[101] IL-6 and TNF-Alpha cytokines produce fatigue and malaise, two of the more prominent symptoms experienced by patients with chronic Lyme disease.^[102]IL-6 is also significantly indicated in cognitive impairment.^[103]

A developing hypothesis is that the chronic secretion of stress hormones as a result of borrelia infection may reduce the affect of neurotransmitters, or other receptors in the brain by cell-mediated pro-inflammatory pathways, thereby leading to the dysregulation of neurohormones, specifically glucocorticoids and catecholamines, the major stress hormones.^[104][105]

SSRI's, SNRI's and tricyclic antidepressants acting on serotonin, norepinephrine and dopamine receptors have been shown to be immunomodulatory and anti-inflammatory against pro-inflammatory cytokine processes, specifically on the regulation of IFN-gamma and IL-10, as well as TNF-alpha and IL-6.^{[106][107][108]} Antidepressants have also been shown to suppress TH1 upregulation.^[109]These studies warrant investigation for antidepressants for use in a psycho-neuroimmunological approach for optimal pharmacotherapy of antibiotic refractory Lyme patients.

The culmination of these new and ongoing immunological studies suggest this cell-mediated immune disruption in the Lyme patient amplifies the inflammatory process, often rendering it chronic and self-perpetuating, regardless of whether the borrelia bacterium is still present in the host, or in the absence of the inciting pathogen in an autoimmune pattern.^{[110][111][112][113][114][115]}

Researchers hope that this new developing understanding of the biomolecular basis and pathology of cell-mediated signaling events caused by Borrelia burgdoferi infection will lead to a greater understanding of immune response and inflammation caused by Lyme disease and, hopefully, new treatment strategies for chronic antibiotic-resistant disease.

[edit] References

[edit] External links

Government and university resources

• CDC Lyme disease page
• CDC - Vector Interactions and Molecular Adaptations of Lyme Disease and Relapsing Fever Spirochetes Associated with Transmission by Ticks

• Links to pictures of Lyme disease (Hardin MD/Univ of Iowa)
• Columbia University - Overview of Neuropsychiatric Lyme Disease
• Pasteur Institute (Borrelia Molecular Biology Home Page)

Professional societies, disease foundations and advocacy resources

• American Lyme Disease Foundation
• The Lyme Disease Foundation
• Lyme Disease Association
• Lyme Disease Network
• Lyme Disease Action-UK based
• Canadian Lyme Disease Foundation
• Eurosurveillance: Lyme disease in Europe
• Greater Hartford Lyme Disease Support & Action Group
• TAGS (Tick Alert Group Support) Inc. Australia
• International Lyme and Associated Diseases Society
• Infectious Disease Society of America

Other resources, memorials etc.

• The National Lyme Disease Memorial Park Project
• Lyme Disease Medical Literature Summaries
• Lyme Disease Research Database
• Quackwatch opinion on lyme treatment
• Living Smart with Patricia Gras: Episode on Lyme Disease