Neglected tropical diseases 2 Flashcards
Which pole of leprosy is mild?
Tuberculoid pole
Which pole of leprosy is severe?
Lepromatous pole
Other than the severity of symptoms how are the two poles of leprosy differentiated between?
The type of immune response that they casue
What type of immune response does tuberculoid leprosy cause?
Cell mediated response, Th1
What does the Cell mediated, th1 response involve?
Granuloma formation–> M.leprae is contained within granulomas
Main role of Th1 cells in leprosy response?
Recruiting macrophages and other effector cells to destroy the infected cells
What type of immune response is lepromatous leprosy associated with?
Antibody-mediated response–> Th2
Issue with antibody mediated response against lepromatous leprosy?
Cells are labelled as foreign with antibodies but they are not destroyed
What happens in lepromatous leprosy because the infected cells are not destroyed?
Leprae proliferates within and around foamy macrophages–> M.leprae is not destroyed
Whole spectrum of leprosy?
Tuberculoid<Borderline tuberculoid<borderline borderline<borderline lepromatous< lepromatous
What happens to the epidermis tissue as you go from tuberculoid leprosy to lepromatous leprosy?
Tissue becomes increasingly disorganised, and bacterial load increases
Difference in granulomas between tuberculoid and lepromatous pole?
Organise, circular in tuberculoid
Disorganised in lepromatous pole, instead having foamy macrophages
Theories of how leprosy causes nerve damage?
Immune injury–> release of inflammatory cytokines or activity of cytotoxic t cells
How can the release of inflammatory cytokines or activity of cytotoxic t cells damage nerves?
Ischaemia
Apoptosis–> Demyelination
How can release of inflammatory cytokines or activity of cytotoxic t cells cause ischaemia?
If inflammation occurs in the nerves, it could cause oedema within the perineural sheath–> swelling causes nerve injury through mechanical compression
Appearance of skin lesions in tuberculoid leprosy?
Skin lesions are flat and diffuse (spread out), pink
Appearance of skin lesions in lepromatous leprosy?
Lesions are raised and less red
Other name for tuberculoid leprosy?
Paucibacillary
Other name for lepromatous leprosy?
Multibacillary
Amount of skin lesions in both leprosies?
Tuberculoid–> 1-5
Lepromatous–> 6 or more
Which type of leprosy always have loss of sensation on the skin lesions?
Tuberculoid
Difference in slit skin smear results between leprosies?
Tuberculoid–> low/no bacterial load, low infectivity
Lepromatous–> High bacterial load, high infectivity
Nerve appearance in tuberculoid leprosy?
Swelling of peripheral nerves due to local inflammation
Nerve appearance in lepromatous leprosy?
Diffuse nerve damage, thickening of peripheral nerves under microscopic examination
Which drugs are used in multi-drug therapy for leprosy?
Dapsone, Clofazimine, Rifampicin
What does Dapsone do?
inhibits bacterial synthesis of dihydrofolic acid which is required for synthesis of purines and pyrimidines, and therefore DNA / RNA
What does Rifampicin do?
inhibits bacterial RNA polymerase, prevents RNA synthesis
What does Clofazimine do?
binds guanine bases of bacterial DNA, prevents DNA replication
How long does tuberculoid leprosy treatment last?
6 months
How long does Lepromatous leprosy treatment last?
12 months
