What are the key differences in diagnosis and treatment between scarlet fever and Kawasaki disease?

From the Guidelines

Scarlet fever and Kawasaki disease are two distinct conditions with different diagnostic features and treatment approaches, despite some overlapping symptoms. The key differences in diagnosis and treatment between scarlet fever and Kawasaki disease lie in their etiology, clinical presentation, and management strategies. Scarlet fever is diagnosed primarily through clinical presentation of a sandpaper-like rash, strawberry tongue, and pharyngitis, with confirmation via rapid strep test or throat culture to identify Group A Streptococcus, and treatment consists of a 10-day course of penicillin or amoxicillin 1. Kawasaki disease, however, requires meeting specific diagnostic criteria including fever lasting at least 5 days plus four of five principal features: polymorphous rash, bilateral conjunctival injection, changes in oral mucosa, extremity changes, and cervical lymphadenopathy, and treatment involves high-dose intravenous immunoglobulin (IVIG) at 2 g/kg as a single infusion, along with high-dose aspirin (80-100 mg/kg/day divided into four doses) during the acute phase, followed by low-dose aspirin (3-5 mg/kg/day) for 6-8 weeks or longer if coronary abnormalities develop 1. The most recent and highest quality study recommends that treatment for Kawasaki disease should be initiated within 10 days of fever onset if possible, and that steroid treatment be restricted to children in whom 2 infusions of IVIG have been ineffective in alleviating fever and acute inflammation 1. Some key points to consider in the diagnosis and treatment of Kawasaki disease include:

• The use of echocardiography to assess for coronary artery abnormalities 1
• The importance of prompt therapy to reduce the risk of coronary artery abnormalities 1
• The potential benefits and risks of steroid treatment in Kawasaki disease 1
• The need for long-term management and follow-up to monitor for cardiac complications 1. Overall, the diagnosis and treatment of scarlet fever and Kawasaki disease require careful consideration of their distinct clinical features and management strategies to optimize patient outcomes.

From the Research

Diagnosis of Scarlet Fever and Kawasaki Disease

• Scarlet fever is characterized by fever, rash, circumoral pallor, oropharyngeal edema, Pastia's lines, and peripheral eosinophilia 2
• Kawasaki disease is diagnosed based on clinical criteria, including fever, bilateral bulbar conjunctivitis, erythematous rash, cervical adenopathy, and swelling of the hands and feet 2, 3
• Laboratory tests, such as complete blood count, erythrocyte sedimentation rate, and C-reactive protein, can support the diagnosis of Kawasaki disease 3

Treatment of Scarlet Fever and Kawasaki Disease

• Scarlet fever is typically treated with antibiotics, such as penicillin or amoxicillin, to eradicate the group A streptococcal infection 2
• Kawasaki disease is treated with intravenous immunoglobulin (IVIG) and aspirin to reduce the risk of coronary artery aneurysms 4, 3, 5
• The use of corticosteroids in Kawasaki disease is being investigated, with some studies suggesting that adjunctive corticosteroid treatment may reduce the risk of coronary artery aneurysms 4
• Biologic agents, such as TNF and IL-1 blockers, may be used in refractory cases of Kawasaki disease 6

Key Differences in Diagnosis and Treatment

• Scarlet fever is typically diagnosed based on clinical presentation and laboratory tests, while Kawasaki disease is diagnosed based on clinical criteria and laboratory tests 2, 3
• The treatment of scarlet fever focuses on eradicating the underlying infection, while the treatment of Kawasaki disease aims to reduce the risk of coronary artery aneurysms 4, 3, 5
• The use of aspirin in Kawasaki disease is controversial, with some studies suggesting that high-dose aspirin may be more effective than low-dose aspirin in reducing the risk of coronary artery aneurysms 5