Paediatric Infections — Common Childhood Illnesses, Vaccines & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Paediatric infections encompass the wide spectrum of infectious diseases disproportionately affecting infants and children, whose immune systems are still developing and who lack prior immunity to many pathogens. Children average 6-8 upper respiratory tract infections (URTIs) per year in the first years of life — largely viral and self-limiting. However, some infections carry serious complications or require urgent treatment: meningococcal disease (bacterial meningitis and septicaemia — potentially fatal within hours); Group A Streptococcal infection (invasive GAS, scarlet fever, toxic shock syndrome); respiratory syncytial virus (RSV) bronchiolitis (the leading cause of infant hospitalisation in the UK, peaking in winter months); pertussis (whooping cough — particularly dangerous in unimmunised infants under 3 months, with 90% of UK pertussis deaths in this age group); and serious bacterial infections causing febrile illness in neonates. Recognising which febrile child needs urgent assessment, which can be managed at home, and which requires antibiotics versus supportive care is the central clinical skill. The NICE Fever in Under 5s guideline (NG143) provides a validated traffic light system (green, amber, red) for risk stratification of febrile children.

Upper respiratory infections: rhinovirus (most common cause of the common cold — over 100 serotypes); coronavirus (seasonal, including COVID-19 — generally mild in immunocompetent children, though multisystem inflammatory syndrome in children (MIS-C) occurs rarely); influenza A and B; parainfluenza virus; adenovirus (pharyngoconjunctival fever). Lower respiratory infections: RSV (respiratory syncytial virus) — the predominant cause of bronchiolitis (peak in October-March, UK); causes annual epidemics; risk factors for severe RSV disease include prematurity, congenital heart disease, chronic lung disease, immunodeficiency. Influenza A and B — more severe lower respiratory disease and post-influenza bacterial superinfection (Staphylococcus aureus pneumonia). Streptococcal infections: Group A Streptococcus (Streptococcus pyogenes) — pharyngitis/tonsillitis ('strep throat'), scarlet fever (erythrogenic toxin-producing strains causing sandpaper rash and strawberry tongue), impetigo, cellulitis, invasive GAS (iGAS — necrotising fasciitis, streptococcal toxic shock syndrome — significant increase in UK incidence post-COVID); Group B Streptococcus (GBS) — neonatal early-onset or late-onset sepsis and meningitis. Meningococcal disease: Neisseria meningitidis serogroups B (most common UK — MenB vaccine from 2015), C (vaccine-preventable), W and Y; risk factors: asplenia, complement deficiency, household contacts of cases. Vaccine-preventable infections causing resurgence: pertussis (Bordetella pertussis — resurgent due to waning vaccine immunity; UK maternal pertussis vaccination in pregnancy protects newborns); measles (MMR); Hib (Haemophilus influenzae type b); pneumococcal (Streptococcus pneumoniae — PCV13 vaccine). Enteroviruses: Hand-Foot-and-Mouth disease (Coxsackie A16 and EV-71 — vesicular rash, fever, self-limiting); herpangina; aseptic meningitis.

The NICE traffic light system (NG143) for febrile children under 5: Green (low risk — manage at home): alert and content, normal skin colour, normal breathing, strong cry; normal capillary refill; moist mucous membranes. Amber (intermediate risk — safety-net and consider referral): nasal flaring, tachypnoea for age, oxygen saturation 95-96%; not responding to social cues; no wet nappies for 12 hours; fever over 5 days; swollen limb or joint; dry eyes. Red (high risk — immediate specialist assessment): pale, mottled, ashen, or blue skin; grunting, marked tachypnoea, severe respiratory distress; non-blanching rash anywhere (purpura — meningococcal septicaemia); bulging fontanelle in infants; neck stiffness; seizure with fever; not roused or appears ill. Specific condition features: RSV bronchiolitis: coryzal prodrome, followed by wheeze, subcostal and intercostal recession, tachypnoea, and SpO2 fall — peak severity at 48-72 hours after hospitalisation. Bacterial meningitis: headache, photophobia, neck stiffness (may be absent in infants under 18 months — bulging fontanelle, high-pitched cry, poor feeding), non-blanching petechiae or purpura (press a glass against the rash — if rash does not blanch under pressure, this is meningococcal septicaemia). Scarlet fever: fine sandpaper-texture generalised erythematous rash, strawberry tongue, 'flushed cheeks with circumoral pallor', pharyngitis, cervical lymphadenopathy.

Clinical risk stratification: NICE NG143 traffic light assessment — heart rate, respiratory rate, capillary refill, colour, responsiveness, hydration status, fever temperature and duration, and presence of non-blanching rash. Throat swab and Group A Strep rapid antigen test (RADT): for pharyngitis — positive RADT reliably indicates GAS; allows targeted antibiotic use (Centor score is used in adults but less validated in children). Blood tests for seriously ill children: full blood count (neutrophilia suggests bacterial infection; lymphocytosis suggests viral); C-reactive protein (CRP — above 20 mg/L suggests bacterial cause, though non-specific; above 100 mg/L makes serious bacterial infection more likely); blood culture (2 sets before antibiotics for suspected sepsis); procalcitonin (better discriminates viral from bacterial infection than CRP). Lumbar puncture (LP): for suspected meningitis — CSF analysis (appearance, white cell count, glucose, protein, culture, PCR for meningococcal and pneumococcal DNA); perform after blood cultures in stable patients; in purpuric/shocked patients, give antibiotics first, LP later. Nasopharyngeal aspirate (NPA) or PCR swab: RSV rapid antigen test or multiplex respiratory PCR panel (identifies RSV, influenza, parainfluenza, adenovirus, rhinovirus, hMPV, coronavirus) — important for infection control cohorting and guiding antivirals. Chest X-ray: for suspected pneumonia (lobar/segmental consolidation suggests bacterial — treat with amoxicillin; perihilar infiltrates suggest atypical/viral). Urine for culture: NICE CG54 — high risk febrile child under 3 months should have a clean catch urine culture.

Viral upper respiratory infections (URTI/common cold): supportive — adequate hydration; antipyretics as needed (paracetamol 15 mg/kg every 4-6 hours or ibuprofen 5-10 mg/kg every 6-8 hours — alternating if needed for fever control, though evidence for superiority is modest); nasal saline irrigation and aspiration for infants. Antibiotics are not indicated for viral URTI. RSV bronchiolitis: no proven effective antiviral (ribavirin not routinely used); supportive care — high-flow heated humidified nasal cannula oxygen for hypoxaemia (SpO2 below 92% or 90% in former premature infants); nasogastric feeding if unable to feed adequately; nebulised hypertonic saline (modest benefit in hospital length of stay). Palivizumab (anti-RSV monoclonal antibody) — monthly injection during RSV season for very high-risk infants (severe CHD, chronic lung disease of prematurity, severe immunodeficiency). Nirsevimab (Beyfortus): new long-acting anti-RSV monoclonal antibody — single IM injection at birth or before RSV season; highly effective (75% reduction in RSV hospitalisation); introduced into UK childhood immunisation programme from 2024-25 season. Bacterial meningitis: IV ceftriaxone 80 mg/kg (maximum 4 g) immediately (do not delay for LP if child is shocked or severely ill); dexamethasone 0.15 mg/kg QDS for 4 days (reduces neurological sequelae in Hib and pneumococcal meningitis — start before or with first antibiotic dose); IV fluids for sepsis resuscitation. GAS pharyngitis/scarlet fever: phenoxymethylpenicillin (penicillin V) 125-500 mg QDS for 10 days (weight-dependent) — complete course reduces risk of rheumatic fever, glomerulonephritis, and invasive GAS. Penicillin allergy: clarithromycin or azithromycin 5-day course. Amoxicillin must be avoided in suspected EBV infection (causes widespread maculopapular rash). Pertussis: azithromycin 10 mg/kg once daily for 5 days; most effective if given in the catarrhal phase (first 2 weeks); post-exposure prophylaxis for unimmunised household contacts.

Meningococcal disease: the most feared paediatric infection — untreated meningococcal septicaemia carries over 50% mortality; even with aggressive treatment, mortality is approximately 5-10% and 10-15% of survivors have major sequelae (limb amputation from necrosis, hearing loss, brain damage, renal failure). The non-blanching purpuric rash must be recognised by parents as requiring immediate 999 emergency call and benzylpenicillin IV/IM (if available — 1.2 g IV adult dose, 600 mg age 10+, 300 mg under 1) before hospital. Untreated streptococcal pharyngitis complications: rheumatic fever (Group A Strep triggering autoimmune cardiac valve damage — the leading cause of acquired heart disease in children globally in low-income countries; largely eliminated in high-income countries by prompt antibiotic treatment); post-streptococcal glomerulonephritis; peritonsillar abscess; retropharyngeal abscess; Lemierre's syndrome (jugular vein septic thrombophlebitis from Fusobacterium). Pertussis complications in infants: apnoea, cyanosis, secondary bacterial pneumonia, pulmonary hypertension — the whoop may be absent in young infants (paroxysmal cough followed by apnoea). Untreated RSV bronchiolitis causing severe hypoxaemia — particularly in preterm infants and those with CHD, congenital airway abnormalities, or immunodeficiency.

Vaccination is the most effective preventive intervention for childhood infections. UK childhood immunisation schedule 2024 includes: 8 weeks — DTaP/IPV/Hib/HepB (6-in-1), MenB (Bexsero), rotavirus; 12 weeks — 6-in-1, rotavirus; 16 weeks — 6-in-1, MenB; 12 months — MMR (measles, mumps, rubella), PCV (pneumococcal), MenB; 3 years 4 months — DTaP/IPV, MMR; 12-13 years — HPV (2 doses 6-12 months apart — protects against cervical cancer); 14 years — Td/IPV (diphtheria, tetanus, polio). For RSV prevention in infants: nirsevimab (Beyfortus) single injection. Maternal pertussis vaccination (Tdap booster at 16-32 weeks of each pregnancy) — protects neonates through transplacental antibody transfer. Hygiene and infection control: handwashing with soap and water for 20 seconds, particularly after contact with a sick child and before feeding; decontamination of surfaces; household isolation during infectious period (measles: 4 days from rash onset; scarlet fever: 24 hours after starting antibiotics; pertussis: 48 hours after antibiotics or 3 weeks from cough onset). Exclusive breastfeeding for the first 6 months: provides passive immunity (maternal IgA, lactoferrin, lysozyme) — reduces RSV hospitalisation risk by 35-40% and protects against UTI, gastroenteritis, and otitis media.

Call 999 immediately for: any child with a non-blanching purpuric or petechial rash (do not wait — this is possible meningococcal septicaemia; give benzylpenicillin IM or IV if available and go to A&E immediately); a baby or child who is pale, mottled, blue or ashen; breathing difficulties with grunting or marked chest recession; a child who is floppy, very difficult to wake, or unresponsive; a seizure; and any infant under 3 months with a fever (temperature over 38°C) — paediatrician assessment is required. Call NHS 111 or see a GP today for: a child aged 3-6 months with a fever over 39°C; any febrile child with amber features (amber traffic light), a bulging fontanelle, severe sore throat making swallowing impossible, or earache with discharge; a rash that is spreading or not going away; a child not improving after 48-72 hours of illness; and a high fever lasting more than 5 days. Manage at home with safety netting if: the febrile child has all green features, is alert and interacting, has normal breathing and skin colour, is drinking fluids, and has no amber or red features.