Pediatric Infectious Diseases and Immunization
This domain tests the febrile infant algorithm, empiric antibiotic choices, classic exanthems, tuberculosis screening and vaccine rules.
Immunization
- In the Iranian EPI schedule, BCG, oral polio and hepatitis B are given at birth; pentavalent (DTP, Hib, hepatitis B) and oral polio at 2, 4 and 6 months; MMR at 12 and 18 months; boosters at 18 months and 6 years.
- Live vaccines (BCG, MMR, OPV, varicella) are contraindicated in severe immunodeficiency, pregnancy and high-dose corticosteroid therapy.
The febrile infant
- Under 28 days with temperature at or above 38.0 C: full sepsis evaluation including lumbar puncture, admission, and intravenous ampicillin plus cefotaxime (or gentamicin).
- 29-90 days: risk stratification using appearance, urinalysis, white cell count and procalcitonin; low-risk infants may be managed with close follow-up.
Specific infections
- Bacterial meningitis beyond the neonatal period: ceftriaxone plus vancomycin; add ampicillin when Listeria is possible.
- Measles: cough, coryza, conjunctivitis, Koplik spots, then a descending maculopapular rash 3-4 days later.
- Tuberculosis: tuberculin skin test induration of 5 mm or more is positive in close contacts and immunocompromised children; 10 mm or more in others.
- Pertussis: paroxysmal cough with post-tussive vomiting and lymphocytosis; azithromycin treats and limits transmission.
Worked example
A 6-week-old has a temperature of 38.2 C, is feeding poorly but has a normal examination. Reasoning: age under 90 days with fever of 38.0 C or higher requires a full sepsis workup including lumbar puncture. Admit, obtain blood, urine and cerebrospinal fluid cultures, and start intravenous ampicillin plus cefotaxime while awaiting results.
Traps
Omitting the lumbar puncture in a young febrile infant; giving MMR to a child on high-dose steroids; treating asymptomatic bacteriuria; and forgetting ampicillin coverage for Listeria under 3 months.