Rheumatic fever epidemiology and demographics


 * Lance Christiansen, D.O.; Associate Editor(s)-in-Chief: ;

Overview
Rheumatic fever, and therefore Streptococus pyogenes infections, are endemic in many developing countries. In countries affected by the industrial revolution, domestic living conditons became less crowded, due to the development of larger homes and families had fewer children. In addition, living conditions became, generally, more hygienic. The introduction of antibiotics, first sulfonamide in the early 1930's and then penicillin in the 1940's, further caused Streptococcus pyogenes infections to become less common and less severe in economically developed countries although they never disappeared.

Developed Countries
The incidence of rheumatic fever in developed nations is low, likely due to improved hygienic standards and routine use of antibiotics for acute pharyngitis. The incidence and prevalence of rheumatic fever in countries like the USA and Canada were approximately 20-40/100,000 persons during the period 1970-1990 with rheumatic heard disease (RHD) occurring sporadically. Over past two decades, the prevalence of rheumatic fever has decreased to 5-20/100,000 persons in Canada and < 5/100,000 persons in the USA with no new cases of rheumatic heart disease. However, the incidence and prevalence of rheumatic fever and rheumatic heart disease has increase to > 100/100,000 persons and 4-10/1,000 persons respectively in Australia.

Developing Countries
The rates of rheumatic fever and rheumatic heart diseases among developing nations have mixed trends. According to recent a recent worldwide report, the incidence rates of rheumatic fever has decreased in India, China and african countries mainly attributed to improved access to medical treatment. This has led to improved survival rates even among people with rheumatic heart disease and there by increase in prevalence rates have been observed. Newer studies relying on echocardiography in the diagnosis of RHD have demonstrated that rates of subclinical carditis is up to 10 times higher than that diagnosed by clinical examination. India, Pakistan, Russia, Mediterranean and African countries have high prevalence rates of RHD. It is estimated that approximately there are 62-78 million RHD patients worldwide which could potentially result in 1.4 million deaths per year. Occurrence of rheumatic fever is associated with low socioeconomic and over crowded conditions.

Impact of Age
Rheumatic fever is commonly reported among age group of 5-15years. Group A beta hemolytic streptococcus pharyngitis is uncommon in children less than 3 years of age, and rheumatic fever is extremely rare. Rheumatic fever among adults is less frequent and accounts for 20% of cases.

Impact of Gender
No predilection towards either gender exists. However, certain manifestations of rheumatic fever such as mitral valve prolapse (carditis) and Sydenham chorea are most often observed among females than males.