Mycobacterium Leprae PDF

Mycobacterium leprae LEPROSY 2  Leprosy Chronic infectious disease caused by Mycobacterium leprae an acid-fast, rod-shaped bacillus. Mainly affect the skin, peripheral nerves and mucosa of the upper respiratory tract also the eyes, a...

Mycobacterium leprae LEPROSY 2  Leprosy Chronic infectious disease caused by Mycobacterium leprae an acid-fast, rod-shaped bacillus. Mainly affect the skin, peripheral nerves and mucosa of the upper respiratory tract also the eyes, apart from some other structures. Affects man only, no animal reservoir 3 Transmission through infectious droplets that are spread by an infectious individual through coughing and sneezing Some people may carry the disease but do not develop the disease (healthy carriers) 4  Pathogenesis Incubation period is very long 3-30 years (average 5yrs) only proportion of infected population gets the disease(5-10%) M. leprae affect schwann cells (cells protecting peripheral nerves) After entering the cells it starts to multiply and causes immune- response which causes inflammation of the skin and the peripheral nerve 5  Pathogenesis cont.. The resulting nerve damage is responsible for main clinical feature of leprosy: i.e anaesthesia and muscle paralysis Repeated injury to, and infection of the anaesthetic extremities lead to their gradual destruction 6 Infiltration of the skin and cutaneous nerves by bacilli leads to the formation of visible lesions often with pigmentary changes 7 The first sign of leprosy is non specific skin lesions which often heals spontaneously 8 Skin lesions 9 10 Skin lesion with loss of sensation 11 12 Skin lesion with loss of sensation 13 There are two forms of leprosy disease  Hyper-reactive tuberculoid (TT) leprosy with small numbers of localized skin lesions containing so few bacilli that they are not seen on microscopy.  Also there is an inappropriately intense granulomatous response that often damage major nerve trunks  Anergic lepromatous (LL)leprosy in which the skin lesions are numerous or confluent and contain huge numbers of bacilli usually seen as clusters or globi within monocytes  Cooler parts of the body such as the ear lobes are particularly heavily infiltrated by bacili. There is no histological evidence of an immune response 14 Lepromatous Leprosy (Early/Late Stages 15 Two forms of Leprosy disease Lepromatous Tuberculoid 16  If the disease progresses its clinical manifestations is determined by the specific immune responsiveness of the patient to the bacillus and there is a distinct immunological spectrum 17  Destruction of the nasal bones may lead to collapse of the nose  in addition large numbers of leprosy bacilli are discharged in nasal secretions in multibacilli disease.  The eye is frequently damaged by direct bacillary invasion which cause paralysis of the eyelids.  Blindness is common and a tragic complication of untreated leprosy 18 Bacilli eye invasion can cause paralysis of the eyelids 19  Blindness is common and tragic complication of untreated leprosy 20  Additional tissue damage is caused by immune reaction that are caused by delayed hypersensitivity or to a vasculitis associated with the deposition of antigen- antibody complexes The formal may rapidly cause severe and permanent nerve damage and requires urgent treatment with anti- inflammatory agents and sometimes surgical decompression of a greatly swollen nerve 21 Diagnosis must be based on the history of the symptoms  careful clinical examination of a person for signs of leprosy. only in rare instances is there a need to use laboratory and other investigations to confirm a diagnosis of leprosy 22 In endemic area any individual with one or more of the following symptoms and signs is a suspected leprosy case and should be examined appropriately One or> pale or reddish, hypo-pigmented patch(es) on the skin with or without loss of sensation Painless swelling or lumps in the face and/or earlobes Enlarged or tender nerves Burning sensation of the skin Numbness or tingling of hands and/or feet Weakness of eyelids hand or/and feet Painless wound or burns on the hands and /or feet 23 Diagnose an individual as having leprosy if ONE of the following CARDINAL SIGNS is positive Skin lesion with loss of sensation One or more enlarged peripheral nerves A positive skin smear 24 There are two methods of classifying leprosy  The number of skin lesions  The presence of bacilli in the skin smear  skin smear are recommended for all new doubtful leprosy suspects and relapse or return to control cases Patients can be classified as:  Multibacillary (MB) leprosy: -Patients with 6 or> leprosy skin lesions and positive smear  Paucibacillary(PB) leprosy : -Patients with 1 to 5 leprosy skin lesions and negative skin smear -This is an important distinction for the selection of treatment 25 26 Test sensation 27 Sensation test 28 One or more enlarged peripheral nerves 29 Laboratory diagnosis The clinical diagnosis can be confirmed by histological examination of skin biopsies detection of acid fast bacilli in nasal discharges scrapings from the nasal mucosa and slit skin smears. The latter are prepared by making superficial incisions in the skin scraping out some tissue fluid and cells and making smears on glass slide. smear are obtained from obvious lesions the earlobes and apparently unaffected skin secretion and skin smears are stained by the ZN method 30  It is assumed that leprosy bacilli that stain strongly and evenly are viable while those stain weakly and irregular are dead  The percentage of the former gives the morphological index which declines during chemotherapy  An increase in morphological index is a useful indication of  non compliance of the patient and the emergence of drug resistance.  The PCR is increasingly used to detect M. leprae in clinical specimens 31  Treatment Multi drug treatment (Rifampicin, Clofazimine and Dapsone) is the only adequate chemotherapy that will kill bacilli Monotherapy is avoided due to development of drug resistant Multi bacillary (MB) patients are treated for 12-18 months while paucibacillary (PB) cases are treated for 6-9 months 32 Control Early detection & treatment No vaccine available Health education 33