Rheumatic valve disease

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Although rheumatic fever was thought to be nearly eradicated from developed countries, it continues to be a challenge because of its high prevalence in the developing world. In addition, new aspects have emerged and are a cause of concern, as indicated by the recent outbreaks in industrial countries.

A variety of epidemiologic studies have shown that the incidence of rheumatic fever and the prevalence of rheumatic heart disease have declined dramatically over the last decades in the developed countries. A number of reasons (table 15.1) have been postulated to explain such a decrease: improvement in living standards, better access to medical care, wider use of antibiotics, as well as natural changes in the streptococcal strains.

In the USA, in the mid 1980s the medical community was surprised by the resurgence of a disease that had been considered to have virtually disappeared. Although the first outbreak was documented in the Intermountain area,1 a nationwide survey of paediatric cardiologists indicated that a definite increase in rheumatic valve disease had occurred in 24 states. The resurgence was very intense in certain areas, where the incidence was similar to that occurring in the early 1960s. After the outbreak, a general decline in new cases was observed, but the disease did not totally disappear. Some disturbing features of the outbreak were that in the majority of cases there was not the antecedent of a sore throat, and that in some patients who had the typical symptomatology, they had taken the recommended treatment for streptococcal pharyngitis (oral penicillin for 10 days). In contrast with what might be expected, the resurgence was not restricted to socioeco-nomically deprived groups. The unresolved questions are whether the disease returned because of an emergence of modified strains, a breakdown of immunity, or simply a slackening of public health vigilance. The most likely explanation for the outbreak is that highly rheumatogenic strains of group A streptococci accounted for local increases in acute rheumatic fever.2 Viewed now in retrospect, through the enormous publicity that accompanied the outbreak, a nationwide survey of all children's hospitals and general hospitals of more than 600 beds in the USA revealed that rheumatic fever was no more common than Kawasaki disease, with approximately 5000 cases of each occurring over four years (from 1984 to 1987), and with no increasing trend.

In the developing countries, the situation is similar to that of industrialised nations in the early 20th century, when rheumatic fever was still one of the leading causes of death and disability in young people. An accurate evaluation of trends of rheumatic fever in these countries is not possible because of a lack of reliable health statistics, but there is overwhelming evidence that the disease continues unabated. The existing information indicates that the magnitude of the problem may not have changed during the last years or may have actually increased in the last 50-60 years. Worldwide estimates of chronic rheumatic heart disease in school age children and young adults range from 4.9 to 30 million.3 Hospital statistics from most developing nations reveal that about 10-35% of all cardiac admissions are for patients with rheumatic fever or chronic rheumatic heart disease (table 15.2). Accordingly, valve replacement accounts for the majority of cardiac surgery in these countries.

Unfortunately, the notion that rheumatic fever is a disease of the poor and the underprivileged is still true at the beginning of the new millennium. The absence of factors that account for the sharp decline ofthe disease in the industrialised countries explains its persistence in the developing world. The difficulties in accessing health care rapidly may explain why streptococcal sore throat (the most important primary cause of this disease) is not treated adequately. A report from Costa Rica shows that a single dose of penicillin benza-thine administered to all patients with sore throat could reduce significantly the incidence of rheumatic fever.4 Another additional problem is that secondary prophylaxis is rarely done, and recurrences are frequent. Changes in the standard of living in these countries, with crowding in urban areas with poor living status (slum areas), has accelerated the propagation of the disease, since streptococcal infection spreads in these type of conditions. At the present time, prevalence of rheumatic heart disease is higher among the urban poor than the rural poor population.

Fortunately, group A streptococcus remains sensitive to penicillin, but it may be only a mat-

ter of time before it becomes resistant (resistance to erythromycin, the second drug of choice, is common and seems to be increasing). Recently, important progress towards the development of an effective vaccine to protect against streptococcal nasopharyngeal infection opens up the possibility of better control of rheumatic fever.5

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