Paediatric Infectious Diseases and Immunology
Infectious disease items test age-stratified fever algorithms, recognition of the classic exanthems and Kawasaki disease, and safe use of the Czech immunisation schedule. Immunology items are usually red-flag recognition rather than detailed laboratory interpretation.
Fever by age
- Under 28 days, any fever of 38.0 C or more means a full sepsis workup: blood culture, urine culture from catheter or suprapubic aspirate, lumbar puncture, full blood count, CRP and procalcitonin, and empirical intravenous antibiotics after admission.
- Between 1 and 3 months, use the same structure but stratify by inflammatory markers and clinical appearance.
- Above 3 months, a well child with a clear source needs no routine lumbar puncture.
Recognisable syndromes
Kawasaki disease: fever for 5 days or more plus 4 of 5 criteria (conjunctivitis, oral changes, cervical lymphadenopathy, rash, extremity changes); treat with intravenous immunoglobulin and aspirin, and arrange echocardiography for coronary aneurysms. Measles, rubella, varicella, parvovirus and scarlet fever are distinguished by the rash sequence, Koplik spots and the enanthem.
Vaccination rules
Live vaccines (MMR, varicella) are contraindicated in significant immunodeficiency, during high-dose steroids and in pregnancy. Inactivated vaccines are safe but may be less immunogenic. Tick-borne encephalitis vaccination is recommended in the Czech Republic because of endemic risk.
Immunology red flags
Two or more severe infections, recurrent pneumonia, deep abscesses, failure to thrive with chronic diarrhoea, family history, or an infection with an unusual organism should prompt immunoglobulin levels, lymphocyte subsets and complement testing.
Worked example
A 6-week-old presents with 38.5 C, mild irritability and no localising signs. Age alone drives management: the infant is under 3 months, so admission, blood and urine cultures, lumbar puncture and intravenous antibiotics follow, even with a normal-looking blood count. Observation without lumbar puncture in this age group is a classic wrong answer.
Traps
Relying on a normal white cell count to exclude sepsis in a neonate; giving MMR to a child on high-dose steroids; missing Kawasaki because the fever has lasted only 4 days at presentation; treating a viral exanthem with antibiotics to be safe.