Bacterial Infections

Borreliosis (Lyme disease)

Background

Borreliosis [bore-El-ee-Oh-sis] (Lyme disease) is caused by a slow-growing spirochaetal bacterium of the Borrelia genus.

There are hundreds of strains and sub-types of Borrelia bacteria. Borrelia burgdorferi sensu stricto (Bb s.s.) is the strain of bacterium which caused an outbreak of infection in Old Lyme, Connecticut, in the US, in 1975. This is how the term Lyme disease came into being. However, in 1909 Arvid Afzelius associated the tick Ixodes ricinus with an expanding rash (Erythema Migrans) and in Europe the disease has been known since the 1980's under a variety of names including Erythema Migrans, acrodermatitis chronica atrophicans and Bannwarth's syndrome.

To date Borrelia burgdorferi (Bb) can be divided into at least 15 genospecies. B. afzelii, B. bavariensis, B. burgdorferi sensu stricto (s.s.), B. garinii and B. spielmanii are all known to be capable of causing disease. There is currently a lack of consistent evidence to determine whether B. bissettii, B. lusitaniae and B. valaisiana also cause disease. The group as a whole is referred to as B. burgdorferi sensu lato (Bb s.l.). Borreliosis is an umbrella term to cover infection of any genospecies.

In the UK Borreliosis predominantly causes neurological complications and cases of Lyme-associated arthritis are uncommon compared to the US.

Signs & Symptoms

The incubation period of Borreliosis is generally from 3-32 days after tick exposure. As with other spirochaetal infections, Borreliosis occurs in stages, with remissions and exacerbations, and different clinical manifestations at each stage. The early stages may be asymptomatic but the patient may present later with more systemic manifestations of the illness.

Early Localised Borreliosis

The early stages of disease classically presents with a single, expanding Erythema Migrans (EM or "bull's-eye") rash, which may last for weeks. However, the rash may be absent or remain hidden under hair or in an inaccessible place. Epidemiological data from the Health Protection Agency over the last few years has demonstrated that fewer than 50% of laboratory-confirmed cases have reported a rash.

There can be a significant range of rashes beyond the classic, target-like EM, including multiple, flat, raised, or blistering rashes. The rash may also vary in colour from light pink to dark purple. Because of the variations misdiagnoses can occur and allergic reaction, ringworm, cellulites and other more common skin ailments can be considered the cause. Rashes can also be missed if they are faint or if the patient's skin is dark.

Recent evidence suggests that B. afzelii can result in more ring-like lesions while B. garinii can result in more irregular lesions, which tend to develop more rapidly.

Other early symptoms tend to be flu-like (mild and without the runny nose, cough and sore throat).

Borrelia lymphocytoma is an uncommon form of early disease. It is normally seen on the earlobe, nipple or scrotum. It appears as a dark, bluish-red, painless patch of skin.

Borrelial Lymphocytoma

Early Disseminated Borreliosis

During this stage the Borrelia spreads into other tissues which can include the skin, nervous system, heart and musculoskeletal system. This can result in a wide variety of signs and symptoms which may present from a few weeks to over a year after the initial infection.

More severe symptoms can include multiple EM (often smaller than an initial lesion), joint and muscle pain and inflammation, radiculopathy (usually occurring months rather than weeks after infection) and carditis with conduction defects (usually partial heart block).

None of the presentations are unique to Borreliosis but combined with a history of tick exposure, or confirmed tick bite, are suggestive of the condition.

Early Neuroborreliosis

The presentation of early neuroborreliosis can include facial or other cranial nerve palsies (paralysis), aseptic (viral-like) meningitis or encephalopathy, Polyradiculitis and peripheral neuritis. Other manifestations such as transverse myelitis, cardiomyopathy, anterior and posterior uveitis, panophthalmitis, hepatitis, myositis and orchitis have been reported.

Facial Palsy

Late Borreliosis

Late disease presents several years after the initial infection and may involve the skin (acrodermatitis chronica atrophicans), the joints (arthritis) or chronic neurological syndromes.

Acrodermatitis chronica atrophicans

Acrodermatitis chronica atrophicans (ACA) is a dermatological manifestation of Borreliosis which can take a chronically progressive course and finally leads to a widespread atrophy of the skin. Involvement of the peripheral nervous system (predominantly sensory polyneuropathy) is frequently observed. The condition is due to the effects of continued active infection. Live spirochaetes have been isolated from skin biopsies as long as ten years after the patient was initially infected.

Arthritis

In the UK and most of Europe, Lyme arthritis is rare. It is more frequently seen in North America. It typically presents as a swelling of the large joints, most often the knee, but rarely causes erosion to the cartilage or bone. Direct infection of the joint has been implicated by culture of spirochaetes or DNA detection in joint fluid. Some patients present with inflammation of the tendons attached to the bone.

Chronic Neurological Syndromes

Direct infection of the nervous system can result in encephalopathy. This may present as memory loss, depression, sensory polyneuropathy or spastic paraparesis. Some manifestations of encephalopathy may resemble Chronic Fatigue Syndrome (CFS) or Fibromyalgia (FM). However, CFS and FM may be triggered by a preceding Bb infection (along with many other possible triggers) but evidence of ongoing, active infection may not be present.

Diagnosis

It is important for a patient's history of possible tick exposure to be taken into account. Lyme borreliosis is endemic throughout the UK and Ireland, although some areas pose a higher risk than others. The Health Protection Agency advises that any area that supports a hard tick population poses a risk. However, an assessment of tick exposure can be problematic as it is also recognised that ticks can be present in urban parks and gardens as well as rural areas. Bites may occur in places that are not considered to be risk areas. It has been highlighted by the World Health Organisation that, "In urban areas, nests of feral pigeons in the lofts of houses can result in invasions of soft ticks (such as the pigeon tick, Argas reflexus) into closely situated flats and apartments" and, "blackbirds in urban parks are carriers of infected ticks". Other urban wildlife species, such as foxes and hedgehogs, can also carry and transport infected ticks.

A diagnosis can be problematic if the patient does not recall a tick bite. Over the last few years, epidemiological data from the Health Protection Agency has demonstrated that fewer than 50% of laboratory-confirmed cases of Lyme borreliosis reported a tick bite. It is therefore important to take into consideration a patient's recreational and occupational activities.

Diagnosis can also be problematic if a patient is infected with other tick-borne pathogens concurrently (co-infections) as this may alter the way in which Borreliosis presents, as well as the way in which it should be treated.

Testing

In the UK, laboratory tests for Borreliosis consist of a two-tier system which detects antibodies to Borreliae. The first of these is an Enzyme Linked Immunosorbent Assay (ELISA). This test superseded the Immunoflorescence Assay (IFA) and is the most commonly used serodiagnostic screening method for Lyme borreliosis.

If the ELISA is positive or equivocal, the sample is then tested with an Immunoblot, also known as a Western blot. Western blot, ELISA and PCR (polymerase chain reaction) can be performed on blood or cerebrospinal fluid (CSF), which is obtained via a lumbar puncture. However, antigen capture in CSF can be extremely elusive; reportedly CSF yields positive results in only 10-30% of patients cultured. Therefore, the diagnosis of neurologic Borrelial infection should not be excluded solely on the basis of a negative CSF antibody analysis.

The detection of Borrelia DNA using PCR can also be performed. This type of molecular test can be useful on joint fluids in cases of suspected Lyme arthritis, and on biopsies from suspected skin infection. It isn't normally used for blood samples as Borreliae are rarely present in the bloodsteam after the early stage of infection. PCR isn't favoured for CSF.

All methods of testing have their limitations and can produce both false-positive and false-negative reactions. Antibodies may not be present for the first few weeks after infection so a negative test does not exclude infection. A second sample taken 2-4 weeks later may then go one to show seroconversion. In late stage disease, patients can be seronegative although this is considered a rare phenomenon.

False-positive results can occur if the patient has antibodies to Bb without having a current infection (e.g. people who are occupationally exposed, such as foresters, or people who are recreationally exposed to tick bites).

The significance of any result, negative or positive, should be interpreted carefully by clinicians in the overall context of a patient's clinical findings and tick-exposure history. Other conditions such as glandular fever, syphilis, or certain neurological illness can also trigger a false-positive reaction.

Other techniques for testing are in development but their clinical usefulness are the subject of debate and have yet to be adequately established.

Treatment

Treatment has become a controversial issue over recent years. Although most doctors would agree that treatment of a Borrelial infection (in its early, localised phase) is clinically successful in most cases, there is far less agreement regarding the treatment of neuroborreliosis and disseminated infection.

In most cases treatment involves a course of oral antibiotics but in cases of neuroborreliosis or cardiac complications, intravenous antibiotics may be required.

The NHS 'Map of Medicine Healthguides' on Lyme disease highlights the different approaches to treatment.

The Jarisch-Herxheimer reaction

The Jarisch-Herxheimer reaction (also referred to as a J-H reaction, Jarisch-Herxheimer, or a herx) can occur during the treatment of Borreliosis. It is believed to result from large quantities of endotoxin-like substances (toxic structural components of bacteria) being released into the body as bacteria are lysed (killed) by the antibiotic therapy. It is thought that the release of endotoxins occurs faster than the body can remove them through the natural detoxification process performed by the liver and kidneys.

The J-H reaction is most commonly associated with the treatment of syphilis (another spirochaetal infection), and was named after two dermatologists (Adolf Jarisch and Karl Herxheimer) who first observed the reaction in syphilis patients during treatment. The reaction also occurs in the treatment of tick-borne Relapsing fever, Q-fever and certain other diseases.

The J-H reaction typically manifests between 1 and 12 hours after the initiation of antibiotic therapy. Symptoms can include fever (generally low grade), chills, headache, myalgias, rigors, hyperventilation, tachycardia, hypertension followed by hypotension (due to vasodilation and declining peripheral resistance), and an exacerbation of cutaneous lesions (which can be mistaken for an allergic reaction to treatment). Careful management (supportive therapy and the use of certain medications such as Diphenhydramine hydrochloride) can help avoid premature cessation of antibiotic treatment.

There is some disagreement regarding the duration of the J-H reaction in the treatment of Borreliosis, with reports varying from a few hours to repeated reactions during the course of treatment.

Transmission

Other than being a tick-borne disease, Borreliosis may be passed from an infected mother to her foetus. It may also be passed through transfusion of infected blood. Borrelia bacteria can survive for up to 48 days at 4 degrees centigrade in human blood processed for transfusion.

Bartonellosis

Background

Bartonellosis [bar-ton-el-lo-sis] is an infection that is caused by bacteria of the Bartonella species. These are faculative intracellular bacteria which are associated with a number of emerging anthropozoonoses. They have been detected in, or isolated from, diverse vertebrate hosts, including humans, various domestic animals, and a wide range of wildlife which serve as natural hosts.

Bartonellosis

Of the ten Bartonella species that are believed to produce infection in humans, the most commonly encountered are Bartonella henselae, B. quintana, and B. bacilliformis. The latter causes Oroya fever and Verruga peruana. Outbreaks are limited to the Andes and cases elsewhere have been found in travellers. B. quintana is the cause of Trench fever, which is found world-wide and causes febrile outbreaks. Poor sanitation and lack of personal hygiene strongly correlates with transmission by the body louse, Pediculis humanus. B. quintana is emerging as a recognised cause of disease amongst homeless people and AIDS sufferers. B. henselae is the cause of Cat Scratch Disease and is found throughout the world in association with domestic and feral cats. In the UK, B. henselae is considered to be endemic to the cat and dog population. Both the cat flea Ctenocephalides felis and Ixodid ticks are arthropod vectors.

Signs & Symptoms

Bartonella infections can cause varying degrees of illness, from benign lymphadenopathy to life-threatening systemic disease. In cases of B. henselae infections, lymph nodes (especially around the head, neck, and upper limbs) may become inflamed. Fever, headache, and loss of appetite may occur. Rare complications are bacillary angiomatosis and Parinaud's oculoglandular syndrome.

A number of studies demonstrate the roll of B. henselae as a concurrent infection in cases of Borreliosis. In one study, elevated levels of B. henselae-specific antibodies were detected by immuneflorescent assay in a number of patients, and B. henselae-specific DNA was detected in their blood and cerebrospinal fluid. B. henselae-specific DNA was also detected in live ticks obtained from the households of two of these patients.

The incubation of B. henselae is generally 3-12 days. A lesion may appear at the site of inocculation, but this may be difficult to identify in cases of Borreliosis when it could be combined with an Erythema Migrans rash. After 1-3 weeks, lymphadenopathy generally appears and is combined with a low-grade fever. Atypical presentations include encephalopathy, joint inflammation, vision loss and respiratory dysfunction. More acute disease may precede, or occur without, lymphadenopathy.

Testing

An indirect Immunofluorescence Assay (IFA) is the principle test used.

Treatment

Bartonella infections are generally treated with macrolides, tertracyclines, aminoglycosides, or chloramphenicol. The latter is not usually used to treat either B. henselae or B. quintana infections, although it has been used to treat B. bacilliformis.

Duration of therapy is commonly at least three weeks, but longer courses may be required for disseminated disease. Because these infections often fail to respond to therapy, or patients experience relapse later, switching to antibiotics from other classes may be needed.