Mycobacterium Leprae

Causes and Meaning of Scientific Name

• Causes Leprosy also known as Hanson’s disease1873

• Chronic infectious disease affects:

• Skin• Peripheral nerves• upper resp tract• Eyes

TRANSMISSION

• Respiratory tract• Skin• Prolonged exposure

needed• Low prevalence of

disease

incidence

• 10 million cases glob• ASIA effected • Pakistan: 1996 contr

Karachi; 56000 t/m• 0.027/10,000 or • 1.68/100,000 pop • Punjab increase• 400 new cases/year

INCUBATION• 2-10yrs• 10% children acquire • Treatment of cases

abolishes infectivityTRANSMISSION• Small children exposed

to heavy shedders of nasal sec

PATHOLOGY

AFB• Single• Parallel bundles• Globular massesSites:• Skin• Mucosa; nasal

septum

CELL• Endotheleal cells BV• Mononuclear cellsGROWTH:• Footpads of mice• Granulomatous L• Armadello: LL

TYPES

TUBERCULOIDNon-progressiveBenignSKIN: macular lesionsAFB: few or noneNerves: asymmetric,

sudden; thick nerveLepromin test: +CD4++

LEPROMATOUS• Progressive• Malignant• Skin: nodular,

abundant AFB• Nerves: symetrical• CD 8 +++ in skin• Lepromin test: -

Classification & immunity

• High level of immunity/granulatio in Tuberculoid

• One or few skin lesio• Flattened with raised

edges/plaque• Hypo-pigmented• No prespiration

• T cell poor/absent• Wide areas affected• Lesions

small,many,shiny, no sensory loss

• Large no of AFB in body even normal skin & nasal smear in histiocytes of dermis

BORDERLINE LEPROSY

• BT: good immunity• Moderate ….mark

loss of pig/perspirat/sensation

• Skin smearsFew or no bacteriaBiopsy may be needed

to classify

• BB; BL: poor immunty

• Slight….moderate

• Several….many

INDETERMINATE STAGES

• Small macule in early stages

• Cant classify in clinical forms

• Persist for months/yrs• Heal completely• Or progress to a

typical

PAUCIBACILLARY• V few bacilli seen• Include tuberculoid• Borderline

tubercuoid• IndeterminateMultibacillaryLep,bl

PAUCIBACILLARY:MULTIBACILLARY

• 1-5 LESIONS• Hypo-pigmented• Assymetrical• Loss f sensation• One nerve involved• (loss of

sensation/muscle weakness)

• More than 5 lesions• Symmetrical lesions• Loss of sensation• Many nerves involved• SKIN SMEAR : for

these 2 states • Go to dermis, 100hp

fields

SYSTEMIC EFFECTS

• Anemia: normocytic• Lymphadenopathy• Eye • Amylodosis• Rheumatoid factor+• Anti-nuclear factor+• LE cells may be seen

in buffy coat

DIAGNOSIS

SCRAPINGS• SKIN• NASAL MUCOSACaution: HIV, HBV,HCVBIOPSYEar lobe skinHistologyZN stain

• ENZYME: Diphenoloxidase

• Serology: none• False + for syphilus• DIAGNOSIS IS

CLINICAL• SMEAR: PAUCI &

MULTI STATE FOR THERAPY

Morphology, Gram Staining, and Oxygen Requirements

• A straight or slightly non-sporing curved rod ZN stain done,1% HCL; fix gently• It is non-motile. Measures .2-.5*5-8um,

Temperature and pH it grows best at and Motility

• It grows best in pH of humans which is 7.35 to 7.45

• It grows best in tropical climates• It also grows on feral armadillos

Contraction of disease

through direct contact air dispersement from coughing or sneezing• Contracting the disease depends on • how susceptible the person is to the disease,

how long you are exposed, • and environmental conditions• Only 10 to 29% of people actually develop

leprosy

Treatment ( yrs)

• Dapsone has been successfully used for over 50 years with emergence of drug resistant.

• Multidrug therapy since 1985 Rifampicin, Clofazamine, and Dapsone has reduced the global incidence by 85%

• Minocycline, clarithromycin, flouroquinolones• Goal: elimination to < 1 per 10,000 population• 2 million need yet to be detected; rehabilitatd

Symptoms

• Symptoms usually take 3 to 5 years to show up after a person has been infected.

• Severe pain, muscle weakness• Loss of fingers or toes• Skin lesions• Symmetrical skin rash mostly found on face, ears,

wrists, elbows, knees, or butt• More severe forms of leprosy can include the

collapsing of the nose

PREVENTION

THOROUGH EXAMINATION• HOUSEHOLD CONTACTS• RELATIVES• Skin• PNS• Therapeutic trial for suspected cases

armadello