LYME DISEASE - DOC by PgvNXP5

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									                                 LYME DISEASE

INTRODUCTION
    Why do tick stay attached to the skin?
                    Barbed hypostomes (biting apparatus)
                    Cement-like salivary secretions which promote attachment
    How are infections transmitted from tick to animal or human?
                    Bugs and neurotoxins are secreted by the salivary glands of ticks
    Lyme disease is the MC vector borne disease in the US
    Borrelia burgdorferi is the causative agent (spirochete)
    Lyme disease has occurred on every continent except antartica
    MC ages is children < 15 yo and adults 30-60yol
    Principle tick vector is Ixodes (several different species)
    Tick hosts: white-foioted filed mouse, deer
    Only 30% of patients will remember a tick bite on presentation
    Most common in spring and summer


PATHOPHYSIOLOGY
    The Borrelia spirochete prefers SKIN, JOINTS, HEART, and NERVOUS SYSTEM tissue
    Late manifestations may be persistent live spirochestes or immunologic response (unknown)
    Three phases of disease
                    Early Lyme Disease = EM, flu-like illness
                    Early Disseminated Lyme Disease = neuropathy, arthritis, carditis
                    Late Lyme Disease = chronic arthritis, neuropathies


EARLY LYME DISEASE
    Tick bites are most common in groin, axilla, gluteal folds, ear lobes
    Skin lesion appears 1 week after bite (on average; range 1 day - 1 month)
    Erythema Migrans (EM)
                    Most characteristic clinical manifestation; occurs in 90% of proven Lyme dz
                    Begins as an erythematous papule or macule
                    Expands in size slowly (1-2 cm/day) to create a patch of erythema
                   The patch may be confluent or have band/ring appearance
                   Central clearing may or may not occur
                   The borders are usually flat but can be raided
                   Sharply demarcated and blanches with pressure
                   Most patients seen 1-7 days after appearance and lesion usually large
                    (8X10cm)
                   Hematogenous spread of spirochetes may lead to MULTIPLE LESIONS
                   Patients can have 20 - 100 lesions (10%)
                   NO blisters, NO mucosal lesions
                   Lesions fade in 1-4 weeks (less with therapy)
    “Viral Syndrome”
                   Fever, malaise, arthralgias, fatigue, lethargy in 80%
                   Low grade fever
                   HSM can occur; can get hepatitis
                   NO cough
                   Mild headache
                   CSF is NORMAL
EARLY DISSEMINATED LYME DISEASE
    Usually a latent period between early lyme dz and early diseminated dz (4-10wks)
    Neurological Manifestations
                   Meningoencephalitis
                           -        Fluctuating course is classic
                           -        Headache, lethargy, sleep distrubances, poor memory and
                                    concentration, often misdiagnosed as viral meningitis
                           -        CXF show mild increase wbc and protein
                           -        CSF B.burgdorferi IgG or IgA is presnetion in 85%
                           -        CXF PCR is only 50% sensitiv
                   Cranial Neuropathies
                           -        Belly’s palsy is the most common; may be bilateral (think of
                                    lyme dz with bilateral bell’s palsy)
                           -        Occurs in 50%
                   Peripheral Neuropathies
                           -        Brachial plexitis, mononeurotis, motor radiculoneuritis
                            -         Weakness, pain, seonsory loss or change with loss of
                                      reflexeds
   Cardiac Manifestations (10%)
                   AV block
                            -         MC cardiac manifestation
                            -         May be intermittent/fluctuating
                            -         3rd degree is MC (50%), 2nd degree 16%, 1st degree 12%
                            -         Gradual resolution occurs as inflammation decreases
                            -         AV block is usually at or above the AV node
                            -         AV block below the bundle of his does occur
                            -         May present with syncope, presyncope, chest pain, dyspnea
                            -         Pacing is occassionally required
                   Myopericarditis
                   CHF uncommon
                   Arrythmias other than blocks uncommon
   Arthritis
                   Classically part of the late manifestation but actually fairly common in early
                    dz
                   Mono or oligoarticular arthritis: knee is the MC joint; shoulder, elbow, hand,
                    wrist, hip, ankles also common
                   Joint tap is intermediate: 25,000 cells/mm3; cultures won’t grow the
                    spirochete
                   Similar to RA except ANA is -ve
   Ocular
                   Keratitis, retinal detachment, optic neuritis, conjunctivitis
LATE LYME DISEASE
    Chronic (LATE) lyme dz = inflammation in an organ system > 1year
    May have relapsing and remitting course
    Arthritis
                    Frank arthritis
                    Periarticular inflammation
                    Arthralgias
                    Fatigue
    Neurologic
                    Chronic encephalopathy: looks like early dementia
                    Can have peripheral neuropathies
    Skin
                    Acrodermatitis Crhonica Atrophicans
                    Atrophic lesion that looks like scleroderma distal to the tick bite site


DIAGNOSIS
    Clinical dx: tick bite hx only 30%, think of in endemic areas, think of with
     rash/arthritis/cardiac manifestations and neurologic findings
    Culture of Borellia is very difficult and generally not done
    Serology is the best diagnostic test
                    Acute and convalescent IgM; false -ves early in disease
                    IgG present after a few months and peaks at 12 months: IgG persistent
                     elevation does not necessarily mean ongoing infection
    ELISA on serum: 90% sensitive and 70% specific; false +ve with syphillus
    Western blood done after positive or equivocal ELISA
    Ddx
                    Viral illness in summer: enteroviruses are common; no diarrhea in Lyme dz
                    Rash: SLE malar rash, erythema marginatum of acute rheumatic fever,
                     erythema nodosum, urticaria, cellulitis, drug eruption, plant dermatitis, insect
                     bites, serum sickness
                    Erythema marginatum: lyme disease migrates SLOWER
                    Rheumatoid arthritis: more joints involved, symmetric polyarthritis, +ve FR
                     and ANA
                    Lyme dz commonly misdiagnosed as seronegative arthritis (reiters, AS, etc)


MANAGMENT
    A vaccine exists and is indicated for high risk individuals
    Prophylaxis after a tick bite is NOT warranted even in endemic areas (prospective study of
     600 tick bites showed prophylaxis not warranted): counsel to return for arthritis, rash,
     headache, myalgias, febrile illness, neurologic symptoms
    See treatment table
    EXAM ANSWER ON TREATMENT
                    The treatment of lyme disease is complicated and dependant on which
                     organ systems are involved s well as the duration and severity of symptoms
                    I do not have the details of treatment memorized; I would consult ID
                    Treatment is continued for 21 - 30 days depending on involvement
                    The basic drugs are: Doxycycline, Penicillin G, Amoxicillin, Ceftriaxone
             Pregnancy: amoxil X 4 weeks



                              RELAPSING FEVER

INTRODUCTION
    Fever caused by several Borrelia species
    Tick-borne relapsing fever
    Maintained in an animal resevoir: wild rodents, squirresl, rabbits
    Western moutain states
    Persons who are exposed to ticks


FEATURES
    Recurrent, cycling fever is the main clue
    Fever, myalgias, headache, N/V
    May develop a pruritic eschar at bite site
    Usually a high temp 39-40
    Petechial rash can occur
    Fever pattern: fever X 3 days, resolves, fever returns a week later, repeats 3-5 times (“I’ve
     had 5 viral infections in the last month”!)
    Dx = blood smear (like malaria smears); may take sever smears; best is when fever starts
     to rise




MANAGEMENT
    Tetracycline or doxycycline




                                     TULAREMIA

INTRODUCTION
    Febrile illness with generalized lymphadenopathy originally described after eating rabbit meat
    Francisella tularensis
    Transmitted from rodents and rabits to humans through a tick vector
    Can also be picked up from inhalation of dust or ingetion of water that is contaminated with
     the bug
    Commonly enters skin cut or abrasion contamined by exporue to an infected animal
FEATURES
    Tende4r erythematous papule at the primary infection site
    Regional lymphadenopathy followed by SKIN ULCERATION which is the main clinical clue
    May lead to BUBOE formation (huge nodes: ddx is bubonic plague)
    Several different forms
                    Ulcerogrlandular: 80%; skin lesion that ulcerated, heals slowly, large regional
                     lymphadenopathy
                    Glandular: 10%; prominent cervical lymph nodes without ulcer formation
                    Other: typhoidal, pulmonary
    Dx = acute and covalescent antibody titers
MANAGEMENT
    Streptomycin X 14 days

    ROCKY MOUNTAIN SPOTTED FEVER (RMSF)

INTRODUCTION
    Acute, febril systemic tick - bourne illness
    Rickettsia rickettsii is the causative agent
    Called “tick fever”
    Relatively uncommon
    SouthEastern US is the MC location now; does occur in Canada
    Any warm blooded animal can house the tick: deer,rabbits, dogs, mice, weasels, farm
     animals


PATHOPHYSIOLOGY
    Ricketsia prefers VASCULAR ENDOTHELIUM for replication hence the VASCULITIS
    Small vessel permeability: rash, extravasation of fluid, hypotension
    Vasculitis microinfarction: stroke, MI, pnumonitis, ARF, etc
    Encephalitis from cerebral vasculitis
    Interstitial pneumonitis looks like ARDS


FEATURES
    General
                    Tick bites by history in 60%; Incubation 2-14 days
                    Sudden onset of fever, headache, myalgias, N/V is classic
                    Myositis of the abominal wall is common (abdo pain)
                    Fever is nearly always fresent early (39-40 degrees)
                    Fever, rash, tick bit triad (only 3%)
    Cutaneous Manifestations
                    Vasculitis
                    Rash in 90%; starts on day 4-6
                    Starts in periphery: ankles, wrists, hands, feet
                    Pink irregular macules about 5 mm, not palpable
                   Progress over hours to axillae, buttocks, neck, trunk
                   Large convalescent areas
                   Tournique may incease distal petechie = Rumpel Leede phenomenon
   Cardiopulmonary Manifestations
                   Myocarditis common
                   Many ECG changes: NSST, AV block, arrythmias, Afig, LVH
                   Pneumonitis and ARDS picture occurs in 25%
   Neurologic Manifestations
                   Lethargy, headache, seizures, coma
                   Sever headache common: 75%
                   Cerebral vasculitis may caus focal deficits, focal seizures
   Diagnosis is difficult; must rely on clinical criteria as testing will not be immediately available
                   Serology: acute and convalescent serology
                   Skin biopsy: immunofluoresent Ab staining of tissue bx is BEST dx test early
                   Isolation is difficult and hazardous b/c of possible spread


MANAGMENT
   Tetracycline oral or chloramphenicol iv until patient afebrile X 5 days
   Manage DIC, ARDS, distributive shock (STEROIDs controversial; generally don’t use)

                                       Q FEVER

   Coxiella burnetti
   Farmers are at risk
   Cattle, sheep, goats and ticks are the primary resevoirs
   POKER PLAYER’S PNEUMONIA = exposure to partuent cats!!
   Most are related to farm animals, not ticks
   VERY INFECTIOUS; one organism can cause disease; as bad as anthrax!
   Severe headache, high fever, myalgias, chills, variable pneumonitis
   May lead to a chronic infectin: hepatitis, endocarditis (culture -ve)
   Diagnosis = serology, ELISA but results not immediately available
   Tx = tetracycline (treatment X 2-5 years for endocarditis!)
   Mortality rate 1%
                                      BABEIOSIS

   Tick bourne, malaria like illness caused by Babesia parasites
   Similar transmissio to Lyme dz: deer and mice resevoirs that are transmitted to humans by
    the Ixodes tick
   Flu-like illnes, fever, chills, headache, fatigue, anorexia
   Rash is not a feature
   Splenectomized patients can get really sick: DIC, ARDS
   Dx = blood smears (like malaria)
   Tx = quinine + clindamycin


     COLORADO TICK FEVER = ORBIVIRUS
   Tick borne illness
   Primarily in the Western USA
   Looks like Rocky Mountain Spotted Fever
   Fever, chills, lethargy, headache, photophobia, abdominal pain, severe myalgias
   Saddle-backed fever: fever on day 2-3 which resolves and returns on day 5-6
   Mx = r/o RMSF, no specific treatment




                              TICK PARALYSIS
   Occurs b/c of a NEUROTOXIN that is released from the tick’s saliva; usually Dermacentor tick
   Occurs in tick seasons: spring and summer
   MOA of neurotoxin not proven but thought to be block at NMJ
   4-7 days after tick bite, ascending paralysis, ataxia or combination
   Bulbar involvement may predominate = facial paralysis, diplopia, dysphagia, etc
   Respiratory failure may occur; may need intubation
   Ddx: GBS, botlism, Myasenthenia, Eaton-Lambet, other peripheral neuropathies, post infectious
    cerebellitis or acute disseminated encephalomyelitis (with ataxic presentations)
   Mx = tick removal , improves within a few hours to days

								
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