Transcript Leprosy

Leprosy
Leprosy (Hansen ‘s disease ) is caused by the
acid- fast bacillus Mycobacterium leprae.Unlike
other mycobacteria , it does not grow in
artificial media or even in tissue culture.Man is
the only natural host of M. leprae.
The precise mode of transmission of leprosy is
still uncertain but it is likely that nasal
secretions play a role.Infection is related to
poverty and overcrowding.Once an individual is
has been infected ,subesquent progression to
clinical disease appears to be dependent on
several factors.Males appear to be more
susceptible than females.
Two polar types of leprosy are recognized
(Ridly-Jopling system):
1.Tuberculoid leprosy:a localized disease that
occurs in individuals with a high degree of cellmediated immunity(CMI).The T cell response to
the antigen releases interferon which activates
macrophages to destroy the bacilli (Th 1
response) but with associated destruction of
the tissue.The lepromin test is positive.
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2.Lepromateous leprosy: a generalized
disease that occurs in individuals with impaired
CMI.Here the tissue macrophages fail to be
activated and the bacilli multiply
intracellularly.Th 2 cytokines are produced. The
lepromine test is negative.
The WHO classification of leprosy depends on
the number of skin lesions and the number of
bacilli detected on the skin smears
:paucibacillary leprosy has 5 or more fewer
skin lesions with no bacilli ;multibacillary
leprosy has 6 more lesions which may have
bacilli.
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Clinical features
The incubation period varies from 2-6 years.The
onset is generally insidious.Acute onset is
known to occur , and the patients may present
with a transient rash , with features of an acute
febrile illness , with evidence of nerve
involvement , or with any combination of
these.
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The major signs of leprosy are:
1.Skin lesions , usually anaesthetic ( generally
tuberculoid ).
2.Thickened peripheral nerves , nerves of
predilection which are superficial or lie in fibroosseous tunnels- ulnar(elbow ), median
(wrist ) ,radial cutenous(wrist ),common
peroneal ( knee), posterior tibial and sural
( ankle) , facial (crossing zygomatic arch
), and greater auricular( posterior triangle
of the neck ).
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The spectrum of disease can be divided into five
clinical groups:
1.Tuberculoid leprosy
The infection is localized because the patient has
unimpaired cell-mediated immunity.The
characteristic , usually single , skin lesion is a
hypopigmented , anaesthetic patch with
thickened ,clearly demarcated edges, central
healing , and atrophy.The face , gluteal region
and extremities are most commonly
affected.The nerve leading to the
hypopigmented patch , and the regional nerve
trunck , are often thickened and tender.
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Unlike other parts of the body ,a tuberculoid
patch on the face is not anaesthetic.Nerve
involvement leads to marked muscle
atrophy.Tuberculoid lesions are known to heal
spontaneously.The prognosis is good.
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2.Borderline tuberculoid (BT)leprosy
This resembles TT but skin lesions are usually
more numerous , smaller ,and may be present
as small ‘satellite’ lesions around larger
ones.Peripheral but not cutaneous nerves are
thickened , leading to deformity of hands and
feet.
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3.Bordeline(BB) leprosy
Skin lesions are numerous, varying in size and
form( macules, papules , plaques ).The
annular,rimmed lesion with punched-out ,
hypopigmented anaesthetic centre is
characteristic .There is widespread nerve
involvement and limb deformity.
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4.Borderline lepromatous (BL) leprosy
There are a large number of florid asymmetrical
skin lesions of variable form , which are
strongly positive for acid- fast bacilli.Skin
between the lesions is normal and often
negative for bacilli.
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5.Lepromatous leprosy (LL)
Although practically every organ can be
involved , the changes in the skin are the
earliest and most obvious
manifestation.Peripheral oedema and rhinitis
are the earliest symptoms.The skin lesions
predominantly occur on the face ,the gluteal
regions and the upper and the lower
limbs.They may be macules , papules ,
nodules or plaques: of these , the macules is
the first to appear.Infiltration is most
noticeable in the ear lobes.
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Thinning of the lateral margins of the eyebrows is
characteristic.The mucous membranes are frequently
involved , resulting in nasal stuffiness , laryngitis and
horseness of voice.Nasal septal perforation with
collapse of the nasal cartilages produces a saddle-nose
deformity.With progression of the disease the typical
leonine facies due to infiltration of the skin becomes
apparent.Glove and stocking anaesthesia ,
gynaecomastia , testicular atrophy , ichthyosis and
nerve palsies( facial , ulnar , median and radial)
develop late in the disease.Neurotrophic atrophy
affecting the phalanges leads to the gradual
disappearance of fingers.Nerve involvement is less
pronounced than in TT.
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Lepra reactions
These are immunologically mediated acute
reactions that occur in patients with the
borderline or lepromatous spectrum of disease
, usually during treatment.Two forms are
recognized :
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A.Non-lepromatous lepra reaction ( type 1
lepra reaction )
This is seen following treatment of patient with
borderline disease ; it is a type IV delayed
hypersensitivity reaction.Both upgrading ( or
reversal ) reactions ( i.e. a clinical change
towards a more tuberculoid form) and
downgrading reactions ( i.e. a change towards
the lepromatous form ) can occur.Neurological
deficits such as an ulnar nerve palsy may occur
abruptly.
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B.Erythema nodosum leprosum (ENL; type ll
lepra reaction )
This is a humoral antibody response to an
antigen-antibody complex ( i.e. a type lll
hypersensitivity reaction).It is seen in 50% of
patients with treated LL.ENL is characterized by
fever , arthralgia , iridocyclitis , crops of painful
, subcutaneous erythematous nodules, and
other systemic manifestations.It may last from
a few days to several weeks.
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Diagnosis
The diagnosis of leprosy is essentially clinical with:
*Hypopigmented/ reddish patches with loss of sensation.
*Thickening of peripheral nerves.
*Acid –fast bacilli(AFB) seen on skin- slit smears/
biopsy.Small slits are made in pinched skin and the
fluid obtained is smeared on a slide and stained for
AFB.
N.B…..patients should be examined carefully for skin
lesions in adequate natural light.Occasionally nerve
biopsies are helpful.Detection of M.leprae DNA is
possible in all forms of leprosy using PCR.
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Management
Multidrug therapy (MDT) is essential because of
developing drug resistance ( up to 40% of
bacilli in some areas are resistance to
dapsone).Much shorter courses of treatment
are now used: the current WHO recommended
drug regimens for leprosy are :
Multibacillary leprosy (LL,BL,BB )
*Rifampicin 600mg once –monthly , supervised
*Clofazimine 300 mg once – monthly, supervised
*Clofazimine 50 mg daily ,self-administered
*Dapsone 100 mg daily ,self-administered
Treatment continued for 6 months
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Paucibacillary leprosy (BT,TT)
*Rifampicin 600 mg once-monthly ,supervised
*Dapsone 100 mg daily , self- administered
Treatment continued for 6 months
Single lesion paucibacillary leprosy
*Rifampicin 600 mg
*Ofloxacin 400 mg
as a single dose
*Minocycline 100 mg
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*Longer therapy may be required in severe
cases.Follow up including skin smears is
essential.
*Patient education is essential.Patients should be
taught self- care of their anaesthetic hands and
feet to prevent ulcers.
*Leprosy should be treated in specialist centres
with adequate physiotherapy and occupational
therapy support.
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Treatment of lepra reaction
This is urgent , as irreversible eye and nerve
damage can occur.Antileprosy therapy must be
continued.Type II lepra reactions (ENL) can be
treated with analgesics , chloroquine ,
clofazimine, and antipyretics.Prednisolone 4060 mg daily for 3-6 months is effective in type I
reactions.
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