Rheumatic fever overview

# Overview
Rheumatic fever is a systemic immune disease that may develop after an infection with Streptococcus bacteria, such as strep throat and scarlet fever. It usually affects the heart, joints, blood vessels, and brain. Based on the duration of symptoms, rheumatic fever may be classified into either acute or chronic. The most common cause of rheumatic fever is Group A beta-hemolytic streptococci infection. If left untreated, rheumatic fever may cause valvular diseases including stenosis, regurgitation of mitral/aortic valves and myocarditis. This may lead to decreased cardiac output, pulmonary edema, and ultimately cardiac failure. For cases without carditis,  the prognosis is excellent, demonstrating no residual heart disease. In cases with preexisting heart disease, the prognosis is poor, leading to mortality. Common complications of rheumatic fever include arrhythmias, systemic emboli, and stroke. Common physical examination findings include fever, cardiac murmurs, and erythema marginatum. Echocardiogram and radiograph may be diagnostic of rheumatic fever. The Jones criteria is used to establish the diagnosis of rheumatic fever. Rheumatic fever is usually treated using antibiotics to control Streptococcus infection and medications such as aspirin and corticosteroids to decrease inflammation. A long-lasting dose of penicillin is important and effective to prevent further complications and recurrence.

# Historical Perspective
Rheumatic fever was first described by Hippocrates, a Greek physician, between 400-370 B.C. The term was first used post-Renaissance by Guillaume de Baillou, a French physician, in the early 1600s. T. Duckett Jones, MD was the first to publish a set of diagnostic criteria in 1944.

# Classification
Based on the duration of symptoms, rheumatic fever may be classified into either acute or chronic.

# Pathophysiology
Rheumatic fever is the result of an autoimmunological sequelae to a virulent Streptococcus pyogenes infection in a patient who was immunologically sensitized from prior infections. During a streptococcal infection, activated antigen-presenting cells, such as macrophages, present the bacterial antigen to helper T cells. Helper T cells subsequently activate B cells and induce the production of antibodies against the cell wall of Streptococcus. However the antibodies also act against the myocardium and joints, producing the symptoms of rheumatic fever.

# Causes
Rheumatic fever is usually caused by an infection with Group A beta-hemolytic Streptococcus pyogenes.

# Differentiating Rheumatic Fever from Other Diseases
Rheumatic fever must be differentiated from other diseases that cause fever, skin rash, nausea and fatigue, such as typhoid fever, malaria, lassa fever, ebola, and scarlet fever.

# Epidemiology and Demographics
The incidence of rheumatic fever among developed countries such as the USA and Canada was approximately 20-40 per 100,000 individuals during the period 1970-1990 with rheumatic heart disease occurring sporadically. Over past two decades, the prevalence of rheumatic fever has decreased to 5-20 per 100,000 individuals in Canada and <5 per 100,000 individuals in the USA with no new cases of rheumatic heart disease. Rheumatic fever is endemic in many developing countries and is usually observed among children between the ages of 5-15.

# Risk Factors
Common risk factors in the development of rheumatic fever include low socioeconomic status, inadequate healthcare, and poor sanitation.

# Screening
Screening of rheumatic fever is important as many cases of rheumatic heart disease are subclinical. Echocardiography among inhabitants of high risk regions is recommended. If any abnormality is detected on echocardiography, further cardiac evaluation is performed followed by antimicrobial therapy.

# Natural History, Complications, and Prognosis
If left untreated, patients with rheumatic fever may progress to develop arrhythmias, systemic emboli, and endocarditis, which may lead to cardiac failure. Common complications of rheumatic fever include stenosis, carditis, and stroke. Prognosis is generally poor if left untreated.

# Diagnosis

## Jones Criteria
The Jones criteria can be used to establish the diagnosis of rheumatic fever. The Jones Criteria for definitive rheumatic fever require evidence of streptococcal infection: elevated or rising antistreptolysin O titre or DNAase and either:
- Two major criteria
OR
- One major and two minor criteria

## History and Symptoms
A detailed and thorough history from the patient is necessary. Specific areas of focus when obtaining a history from the patient include prior rheumatic fever infection, family history of rheumatic fever, and recent streptococcal infection. Common symptoms of rheumatic fever include fever, nose bleeds, and skin rash.

## Physical Examination
Examination of patients with rheumatic fever is usually remarkable for fever, Sydenham's chorea, cardiac murmurs, and erythema marginatum.

## Laboratory Findings
Laboratory findings consistent with the diagnosis of rheumatic fever include elevated inflammatory markers, presence of streptococcal infection, and elevated or rising antistreptolysin O antibody titer.

## Electrocardiogram
On electrocardiogram, rheumatic fever is characterized by PR interval prolongation, conduction abnormalities, arryhthmias or P mitrale depending on the structures involved and the extent of cardiac damage.

## Chest X Ray
On chest x-ray, rheumatic fever is characterized by cardiomegaly and pulmonary edema secondary to heart failure.

## Echocardiography
Echocardiography may be helpful in establishing the diagnosis of carditis and monitoring the progress of valve defects present in rheumatic fever.

# Treatment

## Medical Therapy
The mainstay of therapy for rheumatic fever includes antimicrobial therapy combined with anti-inflammatory medications. The drug of choice is penicillin but ampicillin and amoxicillin are equally as effective. Supportive therapy for rheumatic fever includes continuous use of low dose antibiotics (such as penicillin, sulfadiazine, or erythromycin) to prevent recurrence.

## Primary Prevention
Effective measures for the primary prevention of rheumatic fever include reducing exposure to group A streptococci and antibiotic prophylaxis for streptococcal pharyngitis. Intramuscular benzathine penicillin G and oral penicillin V are the recommended antibiotics in treatment of group  A streptococcal infection in absence of penicillin allergy.

## Secondary Prevention
Secondary prevention strategies following rheumatic fever include antibiotic prophylaxis immediately after the antibiotic course in treatment of rheumatic fever. Duration of prophylactic treatment varies with degree of cardiac damage secondary to rheumatic fever.