What is the diagnostic difference between - and appropriate response to - post-streptococcal acute rheumatic fever and post-streptococcal reactive arthritis?

You are not alone in asking this question because many physicians are confused about these diagnoses. The first thing to consider is the specifics of the Jones Criteria for the diagnosis of acute rheumatic fever.

Jones Major Criteria

1. arthritis
2. carditis
3. chorea
4. erythema marginatum
5. nodules

Jones Minor Criteria

1. arthralgia
2. fever
3. elevated acute phase reactants
4. Elevated sedimentation rate
5. CRP
6. prolonged PR interval
7. evidence of recent strep infection
8. positive throat culture
9. elevated or rising streptococcal antibody titer.

Definite acute rheumatic fever is thought by many physicians to require two of Jones major criteria plus evidence of a recent strep infection. Everyone agrees children who fulfill these criteria are at risk for carditis with a future streptococcal infection and should receive antibiotic prophylaxis. (The belief that children who did not have carditis with their first episode could not have carditis with future episodes has been proven wrong.)

However, pediatricians are often confronted by children who have evidence of a recent streptococcal infection, an elevated sedimentation rate, and arthritis, but do not have a second major criterion. Many believe that these children have rheumatic fever with one major and two minor criteria; others do not believe these children have rheumatic fever. Post-streptococcal reactive arthritis is a term developed to describe these children. It also is used to describe children with definite arthritis following a strep infection when the arthritis is not migratory.

For a long time physicians continued to debate whether these children should receive prophylaxis. However, in January 1993, the American Heart Association published a reformulated version of Jones Criteria that specifically includes children with migratory polyarthritis following a strep infection. Since these children fit the reformulated Jones Criteria for acute rheumatic fever (arthritis is a major criterion; fever and an elevated ESR are two minor), they should be given penicillin prophylaxis.

When considering what to do about other children, it is important to remember that children with definite rheumatic fever receive prophylaxis to prevent streptococcal infections, which may result in carditis and permanent heart damage. Children who have post-streptococcal reactive arthritis have also been shown to be at increased risk for carditis with subsequent strep infections. Therefore, many pediatricians conclude that children with post-streptococcal reactive arthritis should receive prophylaxis. Even though they do not have one major and two minor Jones Criteria, the American Heart Association states that for these children, "physicians may wish to consider penicillin prophylaxis."

In contrast, I often get calls about children with high ASO titers who look well. This means the patient has a significant immunologic reaction to streptococcal infection. However, the ASO titer often remains elevated for eight to ten weeks after the infection is cleared and, in some cases, for months. A high ASO indicates past infection. It does not necessarily indicate current infection nor require treatment. Thus, a rising ASO titer is good evidence of a recent infection but, of itself, does not require treatment.

The important thing to remember is that our responsibility is to the patient. When I talk to my fellows, I remind them we should do what appears to be best for the patient now. We will worry about the broad applicability of the published criteria later. If you have a confusing case or need more information, please let me know.