What are the common febrile rash illnesses in pediatrics and what are their typical age ranges?

From the Guidelines

There are several common febrile rash illnesses in pediatrics, each with typical age presentations, including measles, rubella, chickenpox, scarlet fever, fifth disease, roseola, hand, foot, and mouth disease, Kawasaki disease, and meningococcemia, affecting various age groups. When considering the management of febrile pediatric patients, it's crucial to differentiate between those with serious bacterial infections and those with benign, viral infections, as noted in a study published in the Annals of Emergency Medicine 1. The age-specific risks of serious bacterial infections (SBI) in febrile infants and children have been reported, with the highest risk in neonates (13%) and decreasing with age, as seen in studies from the prepneumococcal vaccine era 1. Some key points to consider in the initial assessment include:

• The definition of fever, typically a rectal temperature of greater than or equal to 38.0 C (100.4 F) 1
• The risk of SBI by age, with neonates having the highest risk 1
• The importance of determining the accuracy or validity of the temperature obtained with a home measuring device 1
• The potential for antipyretic use to result in a normal or lower temperature when the infant or child presents to the ED or other health care setting 1 In terms of specific febrile rash illnesses and their typical age presentations:
• Measles typically affects unvaccinated children of any age but peaks between 1-5 years
• Rubella commonly occurs in unvaccinated children aged 3-10 years
• Chickenpox (varicella) most frequently affects children 2-8 years old
• Scarlet fever typically presents in children 5-15 years of age
• Fifth disease (erythema infectiosum) commonly affects children 3-10 years old
• Roseola (sixth disease) primarily affects infants 6-24 months
• Hand, foot, and mouth disease usually affects children under 5 years
• Kawasaki disease typically occurs in children under 5 years, with peak incidence between 18-24 months
• Meningococcemia can affect any age but is more common in children under 5 years These age ranges reflect typical presentations, though any of these conditions can occur outside these ranges, and vaccination has significantly altered the epidemiology of several of these illnesses, making some quite rare in regions with high immunization coverage.

From the Research

Febrile Rash Illness in Pediatrics

There are several febrile rash illnesses that can affect pediatric patients, including:

• Roseola: typically affects children under the age of 2 years, characterized by a high fever followed by a rash 2
• Erythema infectiosum (fifth disease): usually affects children between 3-12 years old, characterized by a "slapped cheek" facial rash 2
• Scarlet fever: can affect children of any age, characterized by a rash that develops on the upper trunk and spreads throughout the body 2
• Impetigo: a superficial bacterial infection that can affect children of any age, typically found on the face and extremities 2
• Molluscum contagiosum: a highly contagious viral infection that can affect children of any age, characterized by flesh-colored or pearly white papules with central umbilication 2
• Tinea: a common fungal skin infection that can affect children of any age, can affect the scalp, body, groin, feet, hands, or nails 2
• Atopic dermatitis: a chronic, relapsing inflammatory skin condition that can affect children of any age, may present with a variety of skin changes 2

Age of Onset for Febrile Rash Illness in Pediatrics

The age of onset for febrile rash illnesses in pediatrics can vary depending on the specific condition:

• Roseola: typically affects children under the age of 2 years 2
• Erythema infectiosum (fifth disease): usually affects children between 3-12 years old 2
• Scarlet fever: can affect children of any age, but is most common in children between 5-12 years old 2
• Impetigo: can affect children of any age, but is most common in children between 2-5 years old 2
• Molluscum contagiosum: can affect children of any age, but is most common in children between 1-10 years old 2
• Tinea: can affect children of any age, but is most common in children between 3-12 years old 2
• Atopic dermatitis: can affect children of any age, but is most common in children between 6 months to 5 years old 2

Diagnostic Considerations

When evaluating a febrile child with a rash, it is essential to consider the entire clinical presentation, including the appearance and location of the rash, the clinical course, and associated symptoms, such as pruritus or fever 2, 3, 4, 5, 6. A systematic approach involving detailed history taking, careful clinical examination, and attention to epidemiological features can help make a diagnosis and distinguish between benign and life-threatening causes of skin rash in febrile pediatric patients 6.