How do you differentiate and manage Scarlett fever vs acute rheumatic fever?

From the Guidelines

Scarlet fever and acute rheumatic fever are distinct conditions requiring different management approaches, with scarlet fever being an acute infection treated with a single antibiotic course, and acute rheumatic fever being an immune-mediated complication requiring anti-inflammatory treatment and long-term prophylaxis. The management of scarlet fever involves prompt antibiotic treatment, typically with penicillin V (250-500 mg orally twice daily for 10 days) or amoxicillin (50 mg/kg/day divided twice daily for 10 days), as recommended by the Infectious Diseases Society of America 1. For penicillin-allergic patients, alternatives include clindamycin or macrolides. In contrast, acute rheumatic fever is an inflammatory sequela occurring 2-3 weeks after untreated streptococcal pharyngitis, characterized by migratory polyarthritis, carditis, chorea, erythema marginatum, and subcutaneous nodules. Diagnosis relies on the Jones criteria, with evidence of preceding streptococcal infection, as updated by the American Heart Association in 2015 1. Management includes anti-inflammatory therapy with aspirin (80-100 mg/kg/day) or other NSAIDs for arthritis, and corticosteroids for severe carditis. Additionally, all patients with acute rheumatic fever require antibiotic treatment to eradicate any remaining streptococcal infection, followed by long-term prophylaxis with monthly benzathine penicillin G injections or daily oral penicillin to prevent recurrence and rheumatic heart disease, as recommended by the American College of Cardiology/American Heart Association 1. The key distinction is that scarlet fever is an acute infection requiring a single antibiotic course, while acute rheumatic fever is an immune-mediated complication requiring anti-inflammatory treatment and long-term prophylaxis. Some key points to consider in the management of these conditions include:

• The use of penicillin as the first-line treatment for streptococcal pharyngitis, as recommended by the American Heart Association 1
• The importance of long-term prophylaxis in preventing recurrence and rheumatic heart disease in patients with acute rheumatic fever, as recommended by the World Heart Federation 1
• The need for careful diagnosis and management of patients with repeated episodes of acute pharyngitis and cultures or RADTs positive for group A streptococci, as recommended by the Infectious Diseases Society of America 1.

From the FDA Drug Label

To reduce the development of drug-resistant bacteria and maintain the effectiveness of amoxicillin and other antibacterial drugs, amoxicillin should be used only to treat infections that are proven or strongly suspected to be caused by bacteria It is recommended that there be at least 10 days’ treatment for any infection caused by Streptococcus pyogenes to prevent the occurrence of acute rheumatic fever.

The provided drug labels do not directly address the differentiation and management of Scarlett fever vs acute rheumatic fever. However, they do mention the importance of treating Streptococcus pyogenes infections to prevent acute rheumatic fever.

• Key points:
  • At least 10 days of treatment with amoxicillin is recommended for Streptococcus pyogenes infections to prevent acute rheumatic fever 2.
  • Amoxicillin should only be used to treat infections proven or strongly suspected to be caused by bacteria 2. No direct conclusion can be drawn regarding the differentiation and management of Scarlett fever vs acute rheumatic fever from the provided drug labels.

From the Research

Differentiation of Scarlett Fever and Acute Rheumatic Fever

• Scarlett fever is an infectious disease resulting from a group A Streptococcus (group A strep) infection, the same bacteria that cause strep throat, while acute rheumatic fever is an inflammatory sequela of group A Streptococcus pharyngitis that can occur at two to four weeks after infection 3.
• The diagnosis of acute rheumatic fever is based on the presence of documented preceding Group A Streptococcal infection, in addition to the presence of two major manifestations or one major and two minor manifestations of the Jones criteria 4.
• Scarlett fever is characterized by a rash, fever, and sore throat, whereas acute rheumatic fever is characterized by carditis, polyarthritis, and Sydenham's chorea as the most common major manifestations 4, 5.

Management of Acute Rheumatic Fever

• Primary prevention of acute rheumatic fever is accomplished by proper identification and adequate antibiotic treatment of group A beta-hemolytic streptococcal (GAS) tonsillopharyngitis 6.
• Penicillin (either oral penicillin V or injectable benzathine penicillin) remains the treatment of choice for acute rheumatic fever, because it is cost-effective, has a narrow spectrum of activity, has long-standing proven efficacy, and GAS resistant to penicillin have not been documented 6.
• The individual who has had an attack of rheumatic fever is at very high risk of developing recurrences after subsequent GAS pharyngitis and needs continuous antimicrobial prophylaxis to prevent such recurrences (secondary prevention) 6.
• Antibiotic prophylaxis likely reduces the risk of recurrence of rheumatic fever compared to no antibiotics, and intramuscular benzathine benzylpenicillin is probably superior to oral antibiotics 3.

Management of Scarlett Fever

• There is no specific evidence provided in the studies for the management of Scarlett fever, but it is generally treated with antibiotics to eradicate the group A strep infection.
• The focus of the provided studies is on the prevention and management of acute rheumatic fever, which can be a complication of untreated or inadequately treated group A strep infections, including Scarlett fever.