Laboratory diagnosis of leprosy

11
LABORATORY DIAGNOSIS OF LEPROSY T. ARUVI II MBBS

description

laboratory diagnosis of leprosy

Transcript of Laboratory diagnosis of leprosy

Page 1: Laboratory diagnosis of leprosy

LABORATORY DIAGNOSIS OF LEPROSYT. ARUVI

II MBBS

Page 2: Laboratory diagnosis of leprosy

LEPROSY

• Leprosy, also known as Hansen's disease

(HD), is a chronic infection caused by the

bacteria Mycobacterium leprae and

Mycobacterium lepromatosis.

• It is primarily a granulomatous disease of

the peripheral nerves and mucosa of the

upper respiratory tract; skin lesions are the

primary external sign.

Page 3: Laboratory diagnosis of leprosy

DIAGNOSIS OF LEPROSY

• Diagnosis of leprosy is most commonly based on the clinical signs and symptoms.

• Only in rare instances is there a need to use laboratory and other investigations to confirm a diagnosis of leprosy.

• In an endemic country or area, an individual should be regarded as having leprosy if he or she shows ONE of the following cardinal signs:

o skin lesion consistent with leprosy and with definite sensory loss, with or without thickened nerves

o positive skin smears

Page 4: Laboratory diagnosis of leprosy

• For patients presenting the above symptoms, a leprosy diagnosis is confirmed after analysis of tissues biopsied from infected sites.• Typically, a stain for acid-fast bacteria is performed . • Additional steps may include

culturing infected tissue to confirm other bacteria are not involved - M. leprae cannot be culture in vitro

using PCR amplification to verify the presence of DNA specific to M. leprae.

Page 5: Laboratory diagnosis of leprosy

PHOTOMICROGRAPH DEPICTING AN ACID FAST STAIN OF MYCOBACTERIUM LEPRAE

BACTERIA.

Page 6: Laboratory diagnosis of leprosy

SAMPLE COLLECTION FROM SKIN LESION

• Specimen are collected from nasal mucosa, skin lesion and clear lobules.

• Blunt, narrow scalpel is introduced into the nose and a piece of mucous membrane is taken. – NASAL MUCOSA

• Skin is pinched and cut about 5mm and a deep infiltrated layer is taken with a scalpel. – SKIN LESION

Page 7: Laboratory diagnosis of leprosy

A PHOTOMICROGRAPH OF MYCOBACTERIUM LEPRAE TAKEN FROM A

LEPROSY SKIN LESION.

Page 8: Laboratory diagnosis of leprosy

OTHER TESTS

• Lepromin skin test : • Although not diagnostic of exposure to or infection with M leprae, this test assesses a patient's ability to mount a granulomatous response against a skin injection of killed M leprae. • Patients with tuberculoid leprosy or borderline lepromatous leprosy typically have a positive response (>5 mm). • Patients with lepromatous leprosy typically have no response.

Page 9: Laboratory diagnosis of leprosy

• Polymerase chain reaction (PCR): • PCR and recombinant DNA technology have allowed for the

development of gene probes with M leprae –specific sequences. • This technology can be used to identify the mycobacterium in

biopsy samples, skin and nasal smears, and blood and tissue sections.

• Lymphocyte migration inhibition test (LMIT): • As determined by a lymphocyte transformation and LMIT, cell-

mediated immunity to M leprae is absent in patients with lepromatous leprosy but present in those with tuberculoid leprosy.

• Contact or family screening for history of leprosy

Page 10: Laboratory diagnosis of leprosy

PCR DETECTION OF M. LEPRAE DNA IN BIOPSY SAMPLES FROM LEPROSY PATIENTS.

Page 11: Laboratory diagnosis of leprosy

THANK YOU