NCLEX Review Guide: Pediatric Infectious Diseases - Scarlet Fever & Fifth Disease

Scarlet Fever (Scarlatina)

• Scarlet fever is caused by Group A beta-hemolytic Streptococcus pyogenes that produces erythrogenic toxin, resulting in the characteristic rash and systemic symptoms.
• Most commonly affects children ages 5-12 years and spreads through respiratory droplets or direct contact with infected secretions.
• The incubation period is 1-4 days, with patients being contagious for 24-48 hours after antibiotic therapy begins.

Fifth Disease (Erythema Infectiosum)

• Fifth disease is caused by Parvovirus B19 and is characterized by the classic "slapped cheek" appearance followed by a lacy rash.
• Primarily affects children ages 5-14 years with transmission through respiratory droplets and blood products.
• Incubation period ranges from 4-21 days, with patients being most contagious during the prodromal phase before rash appears.

Scarlet Fever Signs & Symptoms

• Strawberry tongue (red, swollen tongue with white coating initially, then bright red) is pathognomonic for scarlet fever.
• Fine, sandpaper-like rash begins on chest/neck, spreads to extremities, and spares the face while creating circumoral pallor.
• Fever (101-104°F), sore throat, headache, and Pastia's lines (petechial rash in skin folds) are characteristic findings.

Fifth Disease Signs & Symptoms

• Classic "slapped cheek" appearance with bright red facial rash that spares the nasolabial fold and circumoral area.
• Lacy, reticular rash appears 1-4 days after facial rash on trunk and extremities, may be pruritic and worsened by heat/sun exposure.
• Mild prodromal symptoms include low-grade fever, headache, and malaise, but many children are asymptomatic during infectious period.

Scarlet Fever Management

1. Implement droplet precautions for 24 hours after antibiotic initiation
2. Administer prescribed antibiotics (typically penicillin or erythromycin) as ordered
3. Provide comfort measures: cool mist humidifier, throat lozenges, soft diet
4. Monitor for complications: rheumatic fever, glomerulonephritis, otitis media

Fifth Disease Management

1. No isolation needed once rash appears - child is no longer contagious
2. Provide supportive care: antipyretics for fever, antihistamines for pruritus
3. Educate family about rash recurrence with heat, exercise, or emotional stress
4. Monitor high-risk contacts (pregnant women, immunocompromised individuals)

High-Yield Facts

• Remember: Scarlet fever = Strep = Sandpaper rash = antibiotic needed
• Fifth disease = "Fifth" finger slap = slapped cheek = viral = supportive care
• Both diseases have circumoral pallor but for different reasons
• Strawberry tongue is pathognomonic for scarlet fever only

Common Pitfalls

• Don't give antibiotics for Fifth Disease - it's viral and self-limiting
• Don't isolate Fifth Disease patients once rash appears - they're no longer contagious
• Remember that Fifth Disease rash can reappear weeks later with triggers
• Always consider pregnancy status of contacts with Fifth Disease exposure