Communicable diseases spread from person to person by the airborne, droplet, contact, fecal-oral, or vector route. Children are especially affected because of close contact in households, schools, and day care, immature immunity, and gaps in vaccination. Most childhood rash illnesses are viral and self-limited, but several can kill — measles, pertussis, severe dengue, and meningococcal disease — and some endanger pregnant contacts or immunocompromised children.

The nurse's roles are to recognize the illness, isolate early, prevent spread, protect vulnerable contacts, support the child through symptoms, and catch complications.

Transmission-based precautions (in addition to standard precautions)

Exposed susceptible contacts in hospital also need airborne precautions: measles contacts from day 5 through day 21 after exposure; varicella contacts from day 8 through day 21 (day 28 if VariZIG was given).

Dengue — three phases

1. Febrile (about 2–7 days): high fever, aches, flushing, positive tourniquet test
2. Critical (around defervescence, about 24–48 hours): capillary leak → rising hematocrit, falling platelets, pleural effusion, ascites, shock — the child may look "better" because the fever is gone
3. Recovery: reabsorption of leaked fluid; risk of fluid overload if IV fluids continue too long

Dengue warning signs — abdominal pain or tenderness, persistent vomiting, clinical fluid accumulation, mucosal bleeding (gums, nose), lethargy or restlessness, liver enlargement, and rising hematocrit with a rapid fall in platelets. Any warning sign → hospital care.

RSV bronchiolitis in infants (see respiratory topics): watch chest retractions, nasal flaring, grunting, and feeding difficulty as signs of worsening distress.

Dehydration in gastroenteritis — the most accurate measure is acute weight loss; also check capillary refill, mucous membranes, tears, sunken fontanel, urine output, and mental status.

Kawasaki disease (not infectious but often confused with rash illnesses): fever for 5 days or more with conjunctival injection, red cracked lips and strawberry tongue, rash, cervical lymph node, and swelling of the hands and feet — urgent referral for IVIG and aspirin (see cardiac topics). This is a supervised exception to the no-aspirin rule; watch for influenza or varicella exposure because of Reye risk.

• Diagnosis is often clinical; confirm reportable diseases: measles (IgM serology and PCR from throat or nasopharyngeal swab and urine), varicella (PCR of a vesicle), pertussis (nasopharyngeal PCR)
• Rapid strep test or throat culture for suspected group A strep
• Mono: heterophile antibody (may be negative in young children) or EBV serology; CBC with atypical lymphocytes
• Dengue: NS1 antigen or PCR in the first days of fever; IgM from about day 5; CBC every day — hematocrit rising with platelets falling signals plasma leakage; liver enzymes; tourniquet test (supports, does not confirm)
• Gastroenteritis: usually clinical; electrolytes and glucose for moderate to severe dehydration

Supportive care — fluids, antipyretics, rest, skin and mouth care for most viral illnesses.

Antipyretic safety

• Acetaminophen (paracetamol) — weight-based dosing; do not exceed the daily maximum (hepatotoxicity); check combination products
• Aspirin is avoided in children and adolescents with viral illness, especially varicella and influenza — Reye syndrome (encephalopathy and liver failure)
• Ibuprofen and other NSAIDs are avoided in dengue (bleeding risk) and commonly avoided in varicella (linked to severe skin and soft-tissue infection)

Specific treatments

• Measles: supportive; vitamin A for all children with measles (WHO: 200,000 IU daily for 2 days at 12 months or older; 100,000 IU at 6–11 months; 50,000 IU under 6 months), with a third dose 2–6 weeks later if eye signs of vitamin A deficiency are present — reduces complications and death
• Varicella: antihistamines and calamine for itching; oral acyclovir for those at higher risk of severe disease (e.g., older than 12 years, chronic skin or lung disease, long-term salicylate or steroid therapy); IV acyclovir for immunocompromised children — hydrate well and monitor kidney function
• Scarlet fever / strep pharyngitis: penicillin or amoxicillin for 10 days to prevent acute rheumatic fever; ask about penicillin allergy
• Pertussis: azithromycin (in young infants, watch for pyloric stenosis — vomiting after feeds); treat close contacts
• Dengue: no antiviral. Febrile phase — paracetamol, oral fluids, rest, daily review. With warning signs — isotonic crystalloid IV fluids titrated to perfusion, urine output, and hematocrit; reduce fluids as leakage ends; transfusion only for significant bleeding. Avoid IM injections
• Gastroenteritis: oral rehydration solution (ORS) in small, frequent amounts (e.g., 5 mL every 1–2 minutes by spoon or syringe); continue breastfeeding and age-appropriate diet; IV fluids for severe dehydration; ondansetron as ordered may reduce vomiting (QT caution)

Post-exposure prophylaxis (PEP)

Vaccination is the main prevention: MMR and varicella are live vaccines — not given to severely immunocompromised children or during pregnancy.

Listed in priority order.

1. Airway, breathing, circulation — apnea monitoring and suction for infants with pertussis; watch for respiratory distress (measles pneumonia); shock recognition in dengue (narrow pulse pressure, cold extremities, delayed capillary refill, restlessness, falling urine output)
2. Isolate immediately on suspicion — for measles and varicella, place in an airborne infection isolation room; staff should be immune; keep pregnant and immunocompromised people away; notify infection prevention
3. Hydration — ORS, frequent small fluids, popsicles for mouth ulcers; daily weight and intake and output; in dengue, hourly urine output and vital signs during the critical phase (aim for adequate output, commonly at least about 0.5 mL/kg/h in children as ordered), hematocrit trend
4. Fever and comfort — weight-based acetaminophen; light clothing; fluids
5. Skin care (varicella) — trim fingernails short, mittens for infants, cool baths with oatmeal or baking soda, loose cotton clothing, calamine; watch for secondary bacterial infection (spreading redness, fever returning)
6. Mouth care — soft diet, cool fluids, avoid acidic foods in hand, foot, and mouth disease
7. Eye care (measles) — dim lights for photophobia; clean eye discharge
8. Report notifiable diseases to public health according to local rules
9. Rest and activity — for mononucleosis, no contact sports or heavy lifting until cleared (usually at least 3–4 weeks) because of the risk of splenic rupture

• Keep the child home from school or day care while contagious (e.g., measles until 4 days after rash onset; chickenpox until all blisters crust; mumps 5 days after swelling; strep at least 12–24 hours after starting antibiotics and fever-free, per local policy)
• Hand hygiene is the most important step for enteric and hand, foot, and mouth disease; clean toys and surfaces; do not share cups or utensils
• No aspirin for children; for dengue, use only paracetamol — no ibuprofen or other NSAIDs
• Dengue home care: plenty of oral fluids, rest, daily follow-up; return immediately for warning signs — especially when the fever breaks; use mosquito nets and repellents so the sick child does not infect mosquitoes
• Finish antibiotics for strep throat even when well
• Vaccinate on schedule; bring records; catch-up doses for missed vaccines
• Tell pregnant contacts about rubella, varicella, or parvovirus exposure so they can be evaluated
• Mosquito control: remove standing water around the home, cover water containers, use screens and repellents approved for children

• Airborne: measles, varicella (plus contact) — negative-pressure room, N95
• Droplet: mumps (5 days after swelling), rubella (7 days after rash), pertussis (5 days of therapy), strep (24 hours of antibiotics)
• Measles: 3 Cs + Koplik spots, rash from hairline downward; vitamin A
• Varicella: lesions in all stages, contagious until all lesions crusted; trim nails; no aspirin
• Roseola: rash appears after fever breaks; fifth disease: slapped cheek
• Scarlet fever: sandpaper rash, strawberry tongue; 10 days of penicillin prevents rheumatic fever
• Measles PEP: MMR within 72 hours or immune globulin within 6 days
• Dengue: danger comes at defervescence; watch warning signs, hematocrit up + platelets down; paracetamol only, no NSAIDs or IM injections
• Dehydration: weight change is the most accurate measure; use small frequent ORS
• Mono: no contact sports — splenic rupture