How can I differentiate Kawasaki Disease from other causes of prolonged fever in children?

To differentiate Kawasaki disease (KD) from other causes of prolonged fever in children, clinicians should focus on specific clinical features that are characteristic of KD and not typically present in other febrile illnesses. KD should be suspected in any child with a fever lasting 5 days or more, especially when accompanied by additional hallmark signs.

Key distinguishing features of Kawasaki disease include:

• Bilateral conjunctival injection without exudate
• Erythema and cracking of the lips, strawberry tongue, or erythema of the oral and pharyngeal mucosa
• Oedema and erythema of the hands and feet
• Polymorphous rash
• Cervical lymphadenopathy

These features may have resolved by the time of assessment, so it is important to ask parents or carers about their presence since the onset of fever NICE NG143.

Children under 1 year may present with fewer clinical features but are at higher risk of coronary artery abnormalities, making a high index of suspicion necessary NICE NG143.

In contrast, other causes of prolonged fever in children often present with different clinical signs:

• Meningococcal disease or bacterial meningitis: fever with non-blanching rash, ill appearance, neck stiffness, bulging fontanelle, decreased consciousness NICE NG143,NICE CKS.
• Herpes simplex encephalitis: fever with focal neurological signs, focal seizures, decreased consciousness NICE NG143,NICE CKS.
• Pneumonia: fever with tachypnoea, chest signs (crackles, nasal flaring, chest indrawing), cyanosis, or low oxygen saturation NICE NG143,NICE CKS.
• Urinary tract infection: fever in young children with urinary symptoms or risk factors NICE NG143,NICE CKS.
• Septic arthritis or osteomyelitis: fever with limb or joint swelling, non-weight bearing NICE NG143,NICE CKS.

Laboratory and imaging investigations may assist but are not definitive for KD diagnosis; clinical recognition remains paramount. Recent literature highlights that KD can sometimes present with shock, mimicking toxic shock syndrome, which underscores the importance of recognizing the classic mucocutaneous features and prolonged fever to differentiate it from other shock causes Wang et al. 2024.

In summary, prolonged fever (>5 days) with the characteristic mucocutaneous signs and lymphadenopathy should raise suspicion of Kawasaki disease, distinguishing it from other febrile illnesses that have different clinical presentations and signs of systemic infection or organ-specific involvement.