Common Childhood Infections

Viral Exanthems I - Red Rash Rumble

• Measles (Rubeola)
  • Virus: Paramyxovirus
  • Prodrome: Cough, Coryza, Conjunctivitis (📌 3 C's), Koplik spots (pathognomonic).
  • Rash: Cephalocaudal maculopapular, confluent, brick-red.
  • Complications: Pneumonia, SSPE.
• Rubella (German Measles)
  • Virus: Togavirus
  • Prodrome: Mild fever, postauricular/suboccipital lymphadenopathy. Forchheimer spots.
  • Rash: Cephalocaudal maculopapular, pink, non-confluent, faster spread.
  • Complications: Congenital Rubella Syndrome (CRS).
• Erythema Infectiosum (Fifth Disease)
  • Virus: Parvovirus B19
  • Rash: "Slapped cheek" → lacy reticular on trunk/limbs.
  • Complications: Aplastic crisis, hydrops fetalis.
• Roseola Infantum (Exanthem Subitum)
  • Virus: HHV-6 / HHV-7
  • Prodrome: High fever (3-5 days), child often well; then defervescence.
  • Rash: Appears after fever; maculopapular, trunk → outward. Nagayama spots.
  • Complications: Febrile seizures.

⭐ Koplik spots in Measles are bluish-white spots on an erythematous base on the buccal mucosa, appearing 1-2 days before the rash.

Viral Exanthems II - Pox, Pink & Slapped Cheeks

• Chickenpox (VZV)

  • Rash: Pruritic, pleomorphic ("dew drop on rose petal" vesicles), all stages simultaneously. Centripetal (trunk > limbs).
  • Prodrome: Mild fever, malaise.
  • Complications: Bacterial superinfection, pneumonia, encephalitis, Reye's (aspirin).
  • Prevention: Vaccine. VZIG for high-risk contacts.

• Rubella (German Measles - Togavirus)

  • Rash: Pink, discrete maculopapular. Face → cranio-caudal spread in 24 hrs. Fades 3 days.
  • Prodrome: Low-grade fever, lymphadenopathy (postauricular, suboccipital). Forchheimer spots.
  • CRS: Deafness, cataracts, cardiac (PDA, PPS). 📌 Mnemonic: "I <3 RUBY EARRINGS".
  • Prevention: MMR vaccine.

• Erythema Infectiosum (Fifth Disease - Parvovirus B19)

  • Rash (3 stages):
    • 1: "Slapped cheek" erythema, circumoral pallor.
    • 2: Maculopapular rash on trunk & limbs.
    • 3: Lacy, reticular rash on extremities; recurs with heat/sun.
  • Complications: Aplastic crisis (hemolytic anemia), hydrops fetalis (pregnancy).

  ⭐ Parvovirus B19 commonly causes arthralgia/arthritis in adults, especially women.

Key Bacterial Infections - Bacterial Blight Brigade

• Diphtheria
  • Agent: Corynebacterium diphtheriae (Gram-positive bacillus).
  • Patho: Exotoxin inhibits protein synthesis → myocarditis, neuritis.
  • Clinical: Greyish, adherent pseudomembrane (pharynx, larynx); "Bull neck" (cervical edema/lymphadenopathy).
  • Rx: Diphtheria Antitoxin (DAT) ASAP + Penicillin/Erythromycin.
• Pertussis (Whooping Cough)
  • Agent: Bordetella pertussis. Highly contagious.
  • Phases: Catarrhal (most infectious) → Paroxysmal (fits of coughs, inspiratory "whoop", post-tussive vomiting, marked lymphocytosis) → Convalescent.
  • Rx: Macrolides (Azithromycin <1 month old, Erythromycin).
• Tetanus (Lockjaw)
  • Agent: Clostridium tetani (anaerobe, spores in soil).
  • Patho: Tetanospasmin (neurotoxin) blocks GABA/glycine release.
  • Clinical: Trismus, risus sardonicus, opisthotonus, painful spasms. Neonatal: umbilical infection.
  • Rx: Human Tetanus Immunoglobulin (TIG) + Metronidazole + Diazepam.

  ⭐ The Spatula Test: Touching posterior pharyngeal wall with a spatula elicits reflex masseter spasm; highly specific for tetanus.

• Haemophilus influenzae type b (Hib)
  • Key syndromes: Meningitis, acute epiglottitis (📌 "Thumb sign" on lateral neck X-ray), pneumonia, septic arthritis.
  • Prevention: Hib conjugate vaccine (part of Pentavalent).

High‑Yield Points - ⚡ Biggest Takeaways

• Measles: Koplik's spots (pathognomonic), cephalocaudal maculopapular rash. Vitamin A reduces morbidity.
• Mumps: Parotitis is classic; orchitis in post-pubertal males is a significant complication.
• Rubella: High risk of Congenital Rubella Syndrome (triad: cataracts, deafness, PDA).
• Diphtheria: Adherent greyish pseudomembrane, bull neck, risk of myocarditis/neuropathy.
• Pertussis: Paroxysmal cough with inspiratory "whoop", post-tussive emesis, marked lymphocytosis.
• Scarlet Fever: Strawberry tongue, sandpaper rash (Pastia's lines); caused by Group A Strep exotoxin.