Pediatric Infections — Causes, Symptoms & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Paediatric infections are among the most common reasons for childhood illness, medical consultation, and hospitalisation worldwide. Children are particularly vulnerable to infections due to immature immune systems, close contact in school/daycare settings, and incomplete vaccination schedules. The spectrum of paediatric infections includes acute respiratory tract infections (most common, predominantly viral), gastrointestinal infections (gastroenteritis), urinary tract infections, meningitis, skin infections, and vaccine-preventable diseases (measles, pertussis, meningococcal disease). In low- and middle-income countries, pneumonia, diarrhoea, and sepsis remain the leading causes of death in children under 5, collectively responsible for over 5 million child deaths annually. In high-income countries, serious infections are less common due to vaccination, clean water, and accessible healthcare. Recognition of the critical difference between self-limiting viral infections and serious bacterial disease requiring immediate treatment is the most important skill in paediatric clinical assessment, and parents should be clearly empowered with evidence-based guidance on red flag signs that warrant emergency care attendance.

Viral infections account for the majority of paediatric acute respiratory infections: respiratory syncytial virus (RSV — most common cause of bronchiolitis and pneumonia in infants), influenza A and B, rhinovirus (common cold), adenovirus, parainfluenza, and SARS-CoV-2. Bacterial causes of serious infections: Streptococcus pneumoniae (pneumonia, meningitis, bacteraemia), Neisseria meningitidis (meningococcal meningitis — fulminant septicaemia), Group A Streptococcus (tonsillitis, scarlet fever, necrotising fasciitis), Staphylococcus aureus (MRSA — skin, bone, pneumonia). Gastrointestinal: rotavirus (most common preventable cause of child diarrhoea deaths before vaccination), norovirus, Salmonella, E. coli. Parasitic: malaria (Plasmodium falciparum — leading cause of fever and death in children in sub-Saharan Africa). Risk factors: age under 5, malnutrition (impairs immunity), incomplete vaccination, lack of breastfeeding, crowded living conditions, immunodeficiency, prematurity, and sickle cell disease.

Respiratory infections: coryza (runny nose), cough, fever, sore throat (pharyngitis/tonsillitis), earache (acute otitis media), wheeze and respiratory distress (bronchiolitis, asthma exacerbation, pneumonia). Signs of severe respiratory illness: respiratory rate above 50 breaths/minute in infants, intercostal recession, nasal flaring, cyanosis, SpO2 below 92%, grunting, and inability to feed. Gastroenteritis: watery diarrhoea, vomiting, fever, abdominal cramps, and signs of dehydration (dry mucous membranes, sunken eyes, reduced skin turgor, depressed fontanelle in infants, decreased urine output, lethargy). Meningococcal septicaemia: non-blanching petechial or purpuric rash (does not fade with a glass pressed against it — a paediatric emergency), high fever, extreme irritability, photophobia, stiff neck, and rapid deterioration. Urinary tract infection: dysuria, frequency, suprapubic pain in older children; non-specific fever, vomiting, and poor feeding in infants. Kawasaki disease: prolonged fever above 5 days, strawberry tongue, conjunctivitis, polymorphous rash, cervical lymphadenopathy, and red swollen hands/feet.

Clinical assessment and history guide diagnosis. Paediatric Sepsis Six (sepsis identification): temperature above 38°C or below 36°C, tachycardia, tachypnoea, poor perfusion, altered mental status, and high or low white cell count. Blood tests: FBC (neutrophilia suggests bacterial infection; lymphopenia in viral sepsis), CRP and procalcitonin (elevated in serious bacterial infection), blood culture (gold standard for bacteraemia — obtain before antibiotics). Urine dipstick and culture (MSU or catheter specimen in infants) for UTI diagnosis. Nasopharyngeal swab or wash for RSV, influenza, and SARS-CoV-2 PCR. Throat swab for Group A Streptococcus. Lumbar puncture (LP) for meningitis diagnosis: CSF microscopy, culture, PCR, protein, and glucose — essential when meningitis is clinically suspected (do not delay for LP if shock is present; stabilise first and treat empirically). Chest X-ray for pneumonia: lobar or bronchopneumonic consolidation, pleural effusion. CXR may be normal in early pneumonia.

Most viral respiratory infections are self-limiting and require only supportive care: adequate hydration, paracetamol or ibuprofen for fever and discomfort, nasal saline drops, and rest. Do not give aspirin to children under 16 years (risk of Reye's syndrome). Bacterial infections requiring antibiotics: streptococcal tonsillitis — amoxicillin or phenoxymethylpenicillin 10 days; community-acquired pneumonia — amoxicillin (first-line for Streptococcus pneumoniae); UTI — trimethoprim or nitrofurantoin (oral) or IV cefuroxime if severely unwell. Meningococcal septicaemia: immediate IV or IM benzylpenicillin or cefotaxime at first clinical suspicion — do not wait for investigations. Bronchiolitis (RSV): supplemental oxygen if SpO2 below 92%, nasogastric feeding if feeding difficulties — no role for bronchodilators or steroids. RSV prophylaxis: nirsevimab (monoclonal antibody) recommended for all infants under 8 months entering their first RSV season. Rotavirus gastroenteritis: oral rehydration therapy (ORS) — WHO-recommended formula; nasogastric or IV fluids if severe dehydration. Malaria: artemisinin-based combination therapy (ACT); severe malaria — IV artesunate.

While most childhood infections are self-limiting, certain infections carry risk of serious complications. Meningococcal septicaemia (Neisseria meningitidis) can kill a previously healthy child within 24 hours from fulminant septicaemic shock, DIC, and multi-organ failure — survivors face limb amputation from purpura fulminans ischaemia, hearing loss, cognitive impairment, and skin scarring. Bacterial meningitis complications: hearing loss (15-20% of pneumococcal meningitis survivors), cognitive impairment, learning disability, epilepsy, hydrocephalus, and cerebral palsy. Pneumonia complications: empyema (pleural pus requiring drainage), lung abscess, septicaemia, and respiratory failure. Group A Streptococcal throat infection complications: rheumatic fever (causing rheumatic heart disease — still a major cause of cardiac morbidity in low-income countries); post-streptococcal glomerulonephritis. RSV bronchiolitis in infants: severe episodes requiring ICU and mechanical ventilation; long-term elevated asthma risk. Chickenpox (varicella) complications: secondary bacterial skin superinfection (S. aureus, GAS), necrotising fasciitis, pneumonia, cerebellar ataxia, and encephalitis. Febrile seizures (3-5% of children aged 6 months to 5 years) are mostly benign and self-limiting but frightening for parents; complex febrile seizures increase subsequent epilepsy risk. Hepatitis A and B, and some enteroviruses can cause fulminant hepatic failure.

Vaccination is the single most effective preventive strategy. Ensure children complete their immunisation schedule — including vaccines against pneumococcal disease (PCV13/PCV15), meningococcal ABCWY, Hib, pertussis (DTaP), MMR (measles, mumps, rubella), varicella, rotavirus, influenza, and HPV. Breastfeeding for at least 6 months provides passive immunity and reduces respiratory and gastrointestinal infection risk. Frequent handwashing with soap and water prevents gastrointestinal and respiratory infection spread. Safe food preparation and clean drinking water prevent enteric infections. Avoid exposure to cigarette smoke — impairs respiratory ciliary function and increases child susceptibility to respiratory infections. Use insecticide-treated bed nets in malaria-endemic regions. RSV burden is reduced by nirsevimab monoclonal antibody prophylaxis in infants.

Call emergency services immediately for a child with: a non-blanching purple or red rash (purpuric rash — possible meningococcal disease), breathing difficulty (laboured breathing, blue lips or skin, grunting, SpO2 below 92%), seizures, loss of consciousness, extreme lethargy (unable to be roused), dehydration with no urine for 8+ hours and sunken fontanelle, or a bulging fontanelle. Seek urgent medical attention for: high fever over 39°C in a child under 3 months or any child appearing very unwell, fever lasting over 5 days, difficulty breathing, signs of dehydration, severe or worsening headache with stiff neck, and a febrile child who has returned from a malaria-endemic country. If in doubt about a sick child, always seek medical advice — paediatric conditions can deteriorate rapidly.