Acute rheumatic fever (ARF) is a multisystem autoimmune disease resulting from infection with group A streptococcus. Episodes of ARF tend to recur in the same individual unless preventive measures are instituted, and each recurrence increases the chance of long-term damage to the heart valves—that is, rheumatic heart disease (RHD). Now uncommon in the developed world, ARF and RHD remain a major public health problem in developing countries and in some poor, mainly indigenous populations in wealthy countries.
The incidence of ARF began to decline in developed countries toward the end of the 19th century, and by the second half of the 20th century, ARF had become rare in most affluent populations. This decline is attributed to more hygienic and less crowded living conditions, better nutrition, improved access to medical care, and, to a lesser extent, the advent of antibiotics in the 1950s. However, according to the World Health Organization (WHO), approximately 500,000 individuals acquire ARF each year, of whom 97% are in developing countries, where the incidence of ARF exceeds 50 per 100,000 children per year. Epidemiologic data from many developing countries are poor, and these are very likely to be underestimates. Much higher rates of 80 to 500 per 100,000 have been documented in careful studies in the indigenous populations of Australia and New Zealand.1 By contrast, the incidence of ARF in industrialized countries is less than 10 per 100,000 children.1,2 There have been several outbreaks of ARF in middle-class populations in the intermountain region of the United States since the mid-1980s, associated with mucoid strains of group A streptococcus, particularly of M type 18.3
The peak incidence of ARF occurs in those aged 5 to 15 years, with a decline thereafter such that cases are rare in adults older than age 35 years.1 First attacks are rare in the very young; only 5% of first episodes arise in children younger than age 5 years, and the disease is almost unheard of in those younger than age 2 years.4 Recurrent attacks are most frequent in adolescence and young adulthood and are diagnosed infrequently after age 45 years.
ARF is equally common in males and females, but RHD is more common in females. Whether this trend is a result of innate susceptibility, increased exposure to group A streptococcus because of greater involvement of women in child rearing, or reduced access to preventive medical care for females is unclear.1 No association with ethnic origin has been found. There is some evidence that between 3% and 6% of any population is susceptible to ARF.5
Epidemiologic and immunologic evidence clearly implicates group A–β-hemolytic streptococcus in the initiation of the disease in a susceptible host. Most patients with ARF have elevated titers of antistreptococcal antibodies. Outbreaks of ARF usually follow epidemics of streptococcal pharyngitis. Adequate treatment of streptococcal pharyngitis reduces the incidence of subsequent ARF, and appropriate antimicrobial prophylaxis prevents recurrences ...