Disease

BASICS


DESCRIPTION


• Lyme disease is a worldwide inflammatory, immune-mediated, multisystem disease that begins with a pathognomonic skin rash. Later, neurologic, cardiac, rheumatologic, dermatologic, and ophthalmologic manifestations may occur.


• It is named after the village of Lyme, Connecticut, where a group of children were studied who had an unusual rash associated with rheumatoid arthritis. As they developed the illness during the warmer months a tick transmission was suspected.


• It commonly begins in the spring, summer, and fall owing to the timing of the tick’s blood meals. Less common in winter.


EPIDEMIOLOGY


• The Centers for Disease Control and Prevention (CDC) began surveillance for Lyme disease in 1982. In 1991, Lyme was classified as a nationally reportable disease.


• It is the most common tick-borne disease in the temperate northern hemisphere, in the USA and Europe.


• It is one of the fastest growing infectious diseases in the USA.


• It has been reported in 49 of the 50 states, but the majority of cases are confined to five geographical areas (New England, Mid-Atlantic, East-North Central, South Atlantic, and West North-Central). It has also been reported in China, Europe, Japan, and parts of the former Soviet Union.


Incidence


• In the 10 states where Lyme disease is most common, the average was 31.6 cases for every 100,000 persons for the year 2005.


• In 2006, 19,931 new cases were reported in the USA.


Prevalence


Of cases reported to the US CDC, the ratio of Lyme disease infection is 7.9 cases for every 100,000 persons.


RISK FACTORS


It is present in an area where one could be bitten by a tick.


GENERAL PREVENTION


• Avoidance of tick bites is the most important way to prevent Lyme disease.


• Avoide the woods, high brush, and grasses where ticks are present.


• Wear protective clothing when out of doors; long pants, long sleeves, and light colored clothing make it easier to spot ticks.


• Apply tick repellant (DEET) to clothing.


• Remove clothing before entering the house.


• Take a shower and examine skin for ticks soon after returning from wooded areas or areas with high grass or brush. Complete inspection of the skin and scalp in children is recommended.


• Remove attached ticks as soon as possible.


• Use care when handling outdoor pets inside homes.


• Reduce deer population in suburban and rural areas.


• Reduce the number of primary hosts on which the deer tick depends, such as rodents.


• A vaccine was developed for its cure, but was voluntarily withdrawn from the market in 2002 by the manufacturer due to poor sales.


PATHOPHYSIOLOGY


• Because the bacteria’s flagellae are located inside the periplasm between the inner and outer cell membranes, the cell is able to travel through bodily fluids and tissues.


• It is believed that the bacteria use a variety of mechanisms to evade the host immune response. The bacteria produce specific outer surface proteins in order to successfully invade and inhabit certain organisms. The bacterial outer surface proteins are able to bind host factor H, a regulator in the complement activating pathway. By binding this regulator, the bacteria may be able to protect themselves from complement killing.


• Once the bacteria have entered the host, it becomes very invasive and can spread quickly throughout the entire system.


• The exact mechanisms for its pathology are still trying to be understood.


• The outer membrane of Borrelia burgdorferi is composed of various unique outer surface proteins. These can be varied in response to immune attack.


• Another way B. burgdorferi evades the immune system is to establish a chronic infection. The exact mechanisms for its pathology are not completely understood.


ETIOLOGY


B. burgdorferi is the infectious agent. It is Gram-negative spirochete in the genus Borrelia and is named for Willy Burgdorfer who isolated it from the intestine of the Ixodes tick in 1982.


• Its life cycle is complex and requires ticks, rodents, and deer at various times. The white-footed mouse is the primary reservoir for the bacteria.


• The bacteria are maintained in a natural cycle of infection by ticks. The ticks acquire and transmit the bacteria by feeding on the mouse, which acts as a reservoir. Ixodes ticks harbor the bacteria in their stomachs.


• After attaching themselves to deer, the ticks transfer the bacteria during a blood meal. The ticks fall off onto vegetation and are transferred inadvertently to humans as they travel in tick-infected areas and are bitten.


• Once the bacteria enter the host it becomes very invasive and can spread very quickly throughout the entire system.


• The disease is not transmitted from one human to another.


DIAGNOSIS


• Ocular symptoms: Blurred vision, eye pain, injection of conjunctiva, diplopia, floaters, progressive visual loss, paresthesias


• Ocular manifestations: Third, fourth, or sixth cranial nerve palsies with diplopia, conjunctival injection, follicular conjunctivitis, keratitis, exposure keratopathy (facial nerve palsy) with hypesthesia, idiopathic orbital inflammation, episcleritis, scleritis, granulomatous anterior uveitis, pars planitis, vitreitis, afferent pupillary defect, optic and retrobulbar neuritis, ischemic optic neuropathy, retinal arteriole occlusion, optic nerve edema, retinitis


• Ocular complaints usually occur during stages I and II (see the ‘Physical Exam’ section below).


HISTORY


• Travel to an endemic area


• Tick bite


PHYSICAL EXAM


• Complete systemic, neurologic, and ophthalmologic examinations


Stage 1:


• The diagnosis of Lyme disease is based on clinical features in a person who has traveled to or lives in an endemic area during the spring, summer, or fall.


• After the tick bite, the first symptom is a skin rash called erythema migrans, which is usually a flat, reddish rash that spreads from the site of the bite.


• The rash is usually >2 inches wide and can grow larger.


• It often develops a central clear area known as a “bull’s eye.” The rash doesn’t itch or hurt.


• Some individuals do not recall the rash.


• Ophthalmological manifestations include conjunctivitis and periorbital edema.


• Other symptoms at this stage can include fever, chills, nausea, muscle and joint aches, fatigue, headache, severe stiff neck, and swollen lymph nodes.


Stage 2:


• Early infection (1–4 months) occurs when the spirochete has disseminated to many organs including the skin, heart, joints, and nervous system. Fatigue may be present.


• The original skin lesion may fade and then recur and become chronic and may appear in other areas of the body.


• Ophthalmological manifestations include blepharospasm, iritis/uveitis, panophthalmitis, choroiditis, optic disc edema, macular edema, pseudotumor cerebri, optic neuropathy, nonarteritic ischemic optic neuropathy, temporal arteritis, optic atrophy, Horner’s syndrome, and Argyll Robertson pupil.


• Cardiac effects include palpitations, arrhythmias, and A-V blocks.


• Neurologic changes include meningitis, meningoencephalitis, cranial neuritis, and radiculoneuritis. Severe headaches, nausea, vomiting, and photophobia may occur.


Stage 3:


• Clinical manifestations may continue for years.


• Ophthalmological manifestations include stromal keratitis, episcleritis, orbital myositis, and cortical blindness.


• Skin changes called acrodermatitis chronica atrophicans may be present as a red swollen skin area that causes the underlying skin to atrophy.


• Arthritis may occur and be present in the majority of patients and may simulate rheumatoid arthritis.


DIAGNOSTIC TESTS & INTERPRETATION


Diagnostic Procedures/Other


• Two-step diagnosis with a screening assay and confirmatory Western blot for B. burgdorferi.


• Serum RPR and FTA-ABS. High positive FTA-ABS titer may produce a low false-positive antibody titer against B. burgdorferi.


• Consider lumbar puncture when meningitis is suspected or neurologic signs or symptoms are present.


DIFFERENTIAL DIAGNOSIS


The differential diagnosis of retinitis and optic nerve edema includes cat-scratch disease, syphilis, acute retinal necrosis, and toxoplasmosis.


TREATMENT


ADDITIONAL TREATMENT


General Measures


B. burgdorferi bacteria are very slow growing, with a doubling time of 12–18 h. Since most antibiotics kill bacteria only when they are dividing, this longer doubling time necessitates the use of relatively longer treatment courses for Lyme disease.


Ocular:


• Topical corticosteroids for anterior segment inflammation


Early Lyme disease (including Lyme-related uveitis, keratitis, or seventh nerve palsy):


• Doxycycline 100 mg PO b.i.d for 10–21 days


• In children, pregnant women, and those who cannot take doxycycline, substitute amoxicillin 500 mg PO t.i.d., cefuroxime axetil 500 mg PO b.i.d., clarithromycin 500 mg PO b.i.d., or azithromycin 500 mg PO daily.


Patients with neuro-ophthalmic signs of recurrent or resistant infection:


• Ceftriaxone 2 g intravenously daily for 2–3 weeks


• Alternatively, penicillin G, 20 million units intravenously daily for 2–3 weeks


SURGERY/OTHER PROCEDURES


Tick removal: Removal with forceps is preferred. The tick should not be crushed or squeezed; this may cause regurgitation of blood from the tick into the skin thereby increasing the likelihood of Borrelia transmission. After the tick has been removed the site should be cleansed.


ONGOING CARE


FOLLOW-UP RECOMMENDATIONS


Every 1–3 days until improvement is demonstrated, and then weekly until resolved


PATIENT EDUCATION


• Wear protective light colored clothing so as to make it easier to spot ticks.


• Carefully inspect skin for ticks.


• Remove ticks rapidly.


• Remove clothing when entering the house.


• Shower after entering the house.


PROGNOSIS


• Most patients respond well to antibiotics.


• Prognosis depends upon promptness of diagnosis and treatment.


COMPLICATIONS


Ophthalmic complications include visual loss from a variety of mechanisms.


ADDITIONAL READING


• Aaberg TM. The expanding ophthalmologic spectrum of Lyme disease. Am J Ophthalmol 1981:77–80.


• Ehlers J, Shah C. (Eds). The Wills eye manual. 5th edn. Wolters Kluwer/Lippincott, Williams and Wilkins, 2007:371–372.


• Nau R, Christen HJ, Eiffert H. Lyme disease – current state of knowledge. Deutsches Ärzteblatt Int 2009;106(5):72–82.


• Winterkorn JMS. Lyme disease: Neurologic and ophthalmologic manifestations. Surv Ophthalmol 1990;35(3):191–204.


• Winward KE, Smith JL, Culbertson WW, et al. Ocular Lyme borreliosis. Am J Ophthalmol 1989;108:651–657.


CODES


ICD9


088.81 Lyme disease


370.50 Interstitial keratitis, unspecified


372.39 Other conjunctivitis


CLINICAL PEARLS


• Lyme disease has many ophthalmic manifestations, including uveitis, optic neuropathy, and arteritis.


• Lyme disease has many systemic manifestations, including meningoencephalitis and cardiac arrhythmias.


• Lyme disease can be prevented by avoiding tick bites.


• Timely diagnosis and initiation of treatment improve prognosis of Lyme disease.


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Nov 9, 2016 | Posted by in OPHTHALMOLOGY | Comments Off on Disease

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