Lesson topic №29 Острая ревматическая лихорадка (Rheumatic fever)

Rheumatic fever

Gorban V.V., D.M. Department of polyclinic therapy with course of general medical practice (family medicine)

Rheumatic fever

Pathophysiology

Symptoms and Signs

Diagnosis

Prognosis

Treatment

Key Points

Poststreptococcal Reactive Arthritis

Rheumatic fever is a nonsuppurative, acute inflammatory complication of group A streptococcal pharyngeal infection, causing combinations of arthritis, carditis, subcutaneous nodules, erythema marginatum, and chorea.

Diagnosis is based on applying the modified Jones criteria to information gleaned from history, examination, and laboratory testing.

Treatment includes aspirin or other nonsteroidal anti-inflammatory drugs, corticosteroids during severe carditis, and antimicrobials to eradicate residual streptococcal infection and prevent reinfection.

A first episode of acute rheumatic fever (ARF) can occur at any age but occurs most often between 5 years and 15 years of age, which are the peak years of age for streptococcal pharyngitis.

ARF is uncommon before 3 years and after 21 years.

However, preceding symptomatic pharyngitis is recognized in only about two thirds of patients with ARF.

Worldwide, incidence is 19/100,000 (range, 5 to 51/100,000), with lowest rates (< 10/100,000) in North America and Western Europe and highest rates (> 10/100,000) in Eastern Europe, the Middle East, Asia, Africa, Australia, and New Zealand.

The attack rate (percentage of patients with untreated group A streptococcal pharyngitis who develop ARF) varies from < 1.0 to 3.0%.

Higher attack rates occur with certain streptococcal M protein serotypes and a stronger host immune response (likely resulting from as-yet-uncharacterized genetic tendencies).

In patients with a prior episode of ARF, the rate of recurrence of ARF in untreated group A streptococcal pharyngitis approaches 50%, underscoring the importance of long-term antistreptococcal prophylaxis.

Incidence has declined in most developed countries but remains high in less developed parts of the world, especially parts with aboriginal or native populations, such as Alaskan Native, Canadian Inuit, Native American, Australian Aboriginal, and Maori New Zealander, where incidence is as high as 50 to 250/100,000.

However, the continued occurrence in the US of local outbreaks of ARF suggest that more rheumatogenic strains of streptococci are still present in the US.

The prevalence of chronic rheumatic heart disease is uncertain because criteria are not standardized and autopsy is not done routinely, but it is estimated that worldwide there are ≥ 33 million patients with rheumatic heart disease, resulting in about 300,000 deaths annually (1, 2).

Patients who have had rheumatic fever have about a 50% likelihood of having a recurrence if they have another episode of group A streptococcal pharyngitis that is untreated.

Pearls & Pitfalls

Pathophysiology of Rheumatic Fever

•Group A streptococcal (GAS) pharyngitis is the etiologic precursor of acute rheumatic fever, but host and environmental factors are important.

•GAS M proteins share epitopes (antigenic-determinant sites that are recognized by antibodies) with proteins found in synovium, heart muscle, and heart valve, suggesting that molecular mimicry by GAS antigens from rheumatogenic strains contributes to the arthritis, carditis, and valvular damage.

•Genetic host risk factors include the D8/17 B-cell antigen and certain class II histocompatibility antigens.

•Undernutrition, overcrowding, and lower socioeconomic status predispose to streptococcal infections and subsequent episodes of rheumatic fever.

•Remarkably, although GAS infections of both the pharynx and of other areas of the body (skin and soft-tissue structures, bones or joints, lungs, and bloodstream) may cause poststreptococcal glomerulonephritis, nonpharyngitis GAS infections do not lead to ARF.

•The reason for this distinct difference in complications resulting from infection by the same organism is not well understood.

•The joints, heart, skin, and central nervous system (CNS) are most often affected. Pathology varies by site.

Joints

Joint involvement manifests as nonspecific synovial inflammation, which if biopsied sometimes shows small foci resembling Aschoff bodies (granulomatous collections of leukocytes, myocytes, and interstitial collagen).

Unlike the cardiac findings, however, the abnormalities of the joints are not chronic and do not leave scarring or residual abnormalities ("ARF licks the joints but bites the heart").

Heart

Cardiac involvement manifests as carditis, typically affecting the heart from the inside out, ie, valves and endocardium, then myocardium, and finally pericardium.

It is sometimes followed years to decades later by chronic rheumatic heart disease, primarily manifested by valvular stenosis, but also sometimes by regurgitation, arrhythmias, and ventricular dysfunction.