Infection/Immunology Flashcards

Question

2 types of allergic reactions?

Answer 1

Non-IgE mediated - Reflux, tummy pain, eczema, diarrhea - Delayed onset and variable clinical presentation IgE mediated (T1 hypersensitivity) - Swelling, urticarial, angioedema, sneezing, bronchospasm, anaphylaxis - Early phase → caused by histamine release and other mediators from mast cells → urticaria, angioedema, sneezing and bronchospasm - Late phase → 4-6 hours later with nasal congestion in upper airway and cough and bronchospasm in lower airway

Answer 2

Sensitisation: - Antigen of allergen taken up by antigen-presenting cell - Antigen is presented on class II MHC to T helper cells - T cell produces cytokines to cause B cells to proliferate and differentiate into IgE-producing plasma cells - IgE molecules attach via constant regions to Fc receptors on mast cells - Once attached IgE molecules can survive for weeks - → Now sensitized Reaction - When exposed to antigen 2nd time, antigen binds to IgE antibodies on mast cells - To trigger response, 2 IgE molecules must interact with specific antigen - This → release of histamine and other inflammatory mediators - → Capillary dilation, airway constriction, mucus secretion, pain, itching

Answer 3

- Antihistamines - Steroids - Epipen provided for anaphylaxis - Possibly systemic desensitisation

Answer 4

- Lymphadenopathy | - Parotitis

Answer 5

- Recurrent bacterial infections - Candidiasis - Chronic diarrhea - Lymphocytic interstitial pneumonitis (LIP) - → This lymphocytic infiltration of lungs may be caused by a response to HIV infection itself, or may be related to EBV infection

Answer 6

- Opportunistic infections, e.g. Pneumocystis jiroveci (carinii) pneumonia (PCP) - Severe FTT - Encephalopathy - Malignancy → rare in children - >1 clinical feature often present - Unusual constellation of symptoms, esp if infectious, should alert one to HIV infection

Answer 7

- Use of maternal antenatal, perinatal and postnatal ARVs to achieve undetectable maternal viral load at time of delivery - Avoidance of breastfeeding - Active management of labour and delivery, to  avoid PROM or unnecessary instrumentation - Prelabour C- section if mother’s viral load detectable close to delivery

Answer 8

Drugs: - As in adults, 3 or 4 dugs used - PCP prophylaxis with co-trimoxazole given to all infants with HIV or older children with low CD4 Other aspects: - Immunisation → give all routine but not BCG (live), also give additional against influenza, Hep A, B and varicella - MDT management with family to ensure compliance and planning for future - Regular follow up – weight, neurodevelopment, clinical S+S of disease

Answer 9

- Fever - Malaise - Tonsillopharyngitis – often severe, limiting oral ingestion of fluids and food; rarely, breathing compromised - Lymphadenopathy – prominent cervical lymph nodes, often diffuse adenopathy - Fatigue

Answer 10

- Symptomatic - When airway severely compromised, corticosteroids considered - In 5%, group A strep grown from tonsils - → May be treated with penicillin - Ampicillin or amoxicillin may cause florid maculopapular rash in children infected with EBV and should be avoided

Answer 11

- Prolonged fatigue (>6m) → >1/10 pts - Anaemia/neutropenia/ thrombocytopenia - Ruptured spleen – 1/500-1000 cases → avoid contact sports during illness - Neurological complications →Guillain Barre, Bell’s palsy, viral meningitis, encephalitis - Secondary infection → pneumonia, pericarditis (usually only if immunocompromised)

Answer 12

Systemic vasculitis (usually in <5yo) - Specific cause unknown - Important diagnosis b/c aneurysms of coronary arteries are potentially devastating complication

Answer 13

Fever (>38) ≥ 5 days duration + ≥4 of (incomplete if <4): - Polymorphous rash (92%) – many different forms, always extensive - Changes in extremities - eg erythema of palms/soles (80%), indurative oedema, desquamation of fingers/toes - Bilateral non exudative bulbar conjunctivitis - Changes in lips and oral cavity - eg dryness, erythema, fissuring of lips, strawberry tongue (71%) - Cervical lymphadenopathy – least common RED RED RED

Answer 14

- Viral exanthems (e.g. measles, adenovirus, enterovirus, EBV) - Scarlet fever - Staphylococcal scalded skin syndrome - Stevens-Johnson syndrome - Juvenile idiopathic arthritis (systemic onset) - Toxic shock syndrome - Drug hypersensitivity reactions

Answer 15

No diagnostic test | --> Clinical diagnosis

Answer 16

- Self-limiting, treat to reduce coronary aneurysms - Coronary arteries affected in 1/3 within 6w, aneurysms can → subsequent narrowing of vessels → myocardial ischaemia and sudden death - Mortality = 1-2% - IVIG given within 10d – reduce aneurysms - Aspirin – reduce thrombosis - If giant coronary aneurysms – may need long term warfarin - Can use antiplatelet if severe thrombocytosis