CHAPTER 46: ACUTE RHEUMATIC FEVER

INTRODUCTION

Acute rheumatic fever (ARF) is a multisystem autoimmune response to untreated or partially treated group A Streptococcus (GAS) pharyngitis. A single severe episode of ARF or recurrent episodes of ARF can result in permanent heart valve damage known as rheumatic heart disease (RHD). Despite a marked decline in ARF and RHD in the developed world, ARF and RHD persist as major public health problems in developing regions of the world, indicative of inadequate access to health care, poorly functioning health systems, and social inequality.

EPIDEMIOLOGY OF ACUTE RHEUMATIC FEVER AND RHEUMATIC HEART DISEASE

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. The decline in prevalence of RHD in wealthy countries has followed a similar pattern, albeit with a delay compared to ARF incidence, which is explained by the chronic nature of RHD. However, these diseases continue largely unabated in resource-poor countries and in some populations living in relative poverty in industrialized countries.¹

It was previously estimated that approximately 470,000 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.² The most recent estimates from the Global Burden of Disease study puts the RHD burden at 33 million prevalent cases, causing 275,000 deaths and more than 9 million disability-adjusted life-years lost each year.^3,4 The major burden of ARF and RHD is in sub-Saharan Africa, South Asia, and the Pacific region (Fig. 46–1).

The peak incidence of ARF occurs in those aged 5 to 15 years, with a decline thereafter such that cases are rare in adults aged > 35 years.¹ First attacks are rare in the very young; only 5% of first episodes arise in children aged < 5 years, and the disease is almost unheard of in those younger than aged < 2 years. Recurrent attacks are most frequent in adolescence and young adulthood and are diagnosed infrequently after 45 years of age. By contrast, RHD, which usually represents the accumulated damage from multiple ARF episodes in childhood, is most highly prevalent in the young adult years.⁵

ARF is equally common in males and females, but RHD is more common in females in almost all populations.^5,6 Whether this trend is a result of innate susceptibility, increased exposure to GAS 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.⁷

PATHOGENESIS

Epidemiologic and immunologic evidence clearly implicates GAS in the initiation of ARF in a ...