BORRELIOSIS

Phylogeny

• Phylum – Spirochete• Named after French Biologist Amedee Borrel• 36 known species • 05 pathogenic :

– B. burgdorferi sensu stricto – Arthitogenic– B. burgdorferi sensu lato Lyme’s– B. garinii – Neurogenic – B. afzelii - Cutaneous manifestations– B. recurrentis – Relapsing Fever

Introduction

• 1900s, manifestation first reported in Europe– associated it with tick bites (TBD)

• 1975 - outbreak in Lyme, Connecticut - ‘JRA’

• 1982 - Spirochetes from midgut of the black-legged tick (Ixodes scapularis erst dammimi) and named Borrelia burgdorferi after American scientist Willy Burgdorfer

• Commonest tick-borne infection (US) - >16000 / yr

Structure

• slender helical shaped bacteria• Gram negative• Motile • Extracellular pathogen• Aerobic or microaerophilic

Transmission

• Vector-borne disease – N Am / EU

• Rodents / Deer - black-legged tick (Ixodes scapularis) or Western black-legged tick (Ixodes pacificus)

• Transmits B. burgdorferi while feeding on an uninfected host– the spirochetes are present in the midgut and migrate during

blood feeding to the salivary glands, from which they are transmitted to the host via saliva.

• B. burgdorferi cannot penetrate intact skin

Exposure Risk

• Residential exposure to infected ticks during property maintenance, recreation, and leisure activity

• Outdoor occupations• Forestry• Landscaping

Ixodes sp

• a

Life Cycle

• aa

Pathogenesis

• Initial Inoculation• Expression of Osp A / C• Binding to TLR – 1 / 2• Immunological Cascade• Humoral (Ig M / G)• Complement

Clinical Features

• aa

ACA ; BLC

Erythema Chronicum Migrans (ECM)

• 90% develop ECM at the site of inoculation

• 1–36 (average 9) days after the bite

• local spread of the spirochaete ring formation EXPANDING @ few cms / wk

• Zone of clearing behind the advancing ring producing a target-like morphology (BULL’S EYE LESIONS)

• LAN + Constitutional Symptoms

• aa

Acrodermatitis Chronica Atrophica (ACA)

• Syn – Herxheimer’s Disease• late cutaneous manifestation of dissemination• 01 or more years after the original infection • Hands, feet, knees and elbows

• begins as an erythematous plaque, which slowly enlarges and gradually becomes violaceous and atrophic (‘tissue paper atrophy’)

• Spirochaetes have occasionally been cultured

• aa

DDx

• aa

DDx

17

Diagnosis

SEROLOGY

AB-based • ELISA• Western Blot

AG-based• NAAT (PCR / bDNA / TMA / NASBA)

DIRECT ISOLATION

Stains (WSS / DIETERLE / GS / WGS )HPE

HPE

ECM• Focal epidermal spongiosis and parakeratosis can be seen• Tightly cuffed Dermal perivascular lymphocytic infiltrate

may contain Plasma CellsACA• Epidermal Atrophy • liquefaction degeneration of the basal layer and

telangiectasia of the papillary dermis• Diffuse Dermal perivascular lymphocytic infiltrate

containing Plasma Cells• Warthin–Starry stain identified spirochaetes in 40% of cases

of both morphologies

HPE

• aa

Dr.T.V.Rao MD 21

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