Leprosy and plague Flashcards
(39 cards)
How long after starting therapy is a patient non infectious with leprosy? Who gets nodules?
Almost immediately
Nodules only in lepromatous leprosy (image) (and in BL)
leprosy transmission
Respiratory droplets [not proven]
Where can leprosy be cultivated
Mouse foot pads or armadillo
Why are few bacteria cultivated in tuberculoid leprosy?
Cell mediated immunity (phagocytes / T cells) contains infection
Classic skin lesion leprosy
Anaesthetic macules with thickened nerves
Tuberculoid to lepromatotous leprosy is generally a scale with borderline in the middle.
Which has more bacteria cultivated?
Which has larger skin lesions?
Thicker nerves?
Defines borders?
- Lepromatotous are larger with more thickened nerves and bacilli. Often just global erythematous lesions.
Sensation preserved initially - Tuberculoid has more defined borders (better cell mediated immunity)
Leprosy rx? How long?
Rifampicin (monthly)
Dapsone (daily)
Clofazamine daily
and steroids for
Paucibacillary 6 months (TL, BT, B)
Multibacillary 12 months (BB, BL, LL)
Dapsone / rifampicin mechanism
- D inhibits folic acid synthesis
- R inhibits RNA polymerase
Clofazimine key side effect
- Discoloration of skin which may turn icthyotic
When do Leprosy type 1 and 2 reactions occur? What are they? Rx?
- Usually in first two months of rx but can occur any tome
Type -1 due to delayed hypersensitivity to m leprae. Erythema and tenderness of lesions and sometimes rapid nerve damage
Type 2 - Erythema nodosum leprosum. Caused by immune complex deposition. Get systemic upset
- Treat both with steroids
- Erythema nodosum leprosum will also need thalidomide
Which vaccine provides some protection from leprosy
BCG
How many lesions in pure tuburculoid leprosy
Usually 1 (may have a coupe in 1 area) erythematous macule/plaque with well defined borders
Characteristic lesions in borderline leprosy
Has a central lesion with ‘punch out’ normal skin in middle
Seen on biopsy of leprosy? Which stain?
Inflammatory Infiltrate along vessels and nerves
Mycobacteria seen on Modified Ziehl-Neelsen Stain (Wade-Fite Stain)
How do you define Paucibacillary leprosy
Negative samples for AFB
Plague distribution
Madagascar has most worldwide >60% total
Still loads wtf
Plague cause - appearance ? Temp grown at
Yersinia pestis
Gram negative bacillus, bipolar staining
(closed safety pin) - bipolar nuclei
Optimal growth rate 28 º C
Name 2 virulence factors in plague
Yersinia outer membrane proteins (Yops)
-Inhibit phagocytosis
- Downregulate pro inflammatory cytoquines
- Induce cell death
Fraction1 antigen ( 37 o C, antiphagocytic
V antigen LcrV Survive and multiply within
macrophages anti inflamatory activity
Coagulase - Blood clots in the proventriculus of the flea
-Active at 30 ºC
Plauge resevoirs
Urban - Rattus rattus
Rural - other rodents
Plague tranmission
Flea regurgitates infectious remnants (Y pestis) from a
previous blood meal into bite wound
-Ingestion of contaminated animal tissues
-Handling of contaminated animal tissues, laboratory infections
-Man to man (coughing) inhalation pneumonic
[Xenopsylla cheopis]
Where does y pestis go to (if not inhaled)?
Skin -> regional lymph nodes
->lymphatic obstruction -> lymphedema
Thrombosis in blood vessels -> haemorrhagic necrosis
Sudden onset Chills, fever, weakness, headache
Intense pain over a lymph node
Absence of ascending lymphangitis
High fever ?
Bubonic plague -Most common presentation of y pestis
Absence of ascending lymphangitis is key. Usually a single lesion
Plague usually doesnt have skin lesions (bar bubos) but what might you see?
Papules, vesicles, pustules, eschars, carbuncles
- Rarelycellulitis, abscesses Purpuric
->necrotic -> gangrene
Pneumonic plague transmission? outcomes
Inhalation
Haemategonus
100% fatal (often within 24hrs) without Rx
50% with rx
