Acute Rheumatic Fever

Organism Group A p-haemolytic streptococcus (GApHS). The M-protein in the wall of the streptococcus is responsible for its virulence and certain predominant sero-types, 1, 3, 5, 6, 14, 18, 19, 24, 27 and 29, have a much greater rheumatogenic potential.

Clinical features ARF is a delayed non-sup-purative sequel of upper respiratory tract infection or scarlet fever with GApHS. ARF is important because it can lead to rheumatic heart disease (RHD), the resulting cardiac damage producing considerable morbidity and mortality.

Diagnosis of ARF is based on major and minor clinical criteria and a rising serum antibody titre of a recent streptococcal infection by the antistreptolysin-O titre (ASOT), antihyaluronidase or anti-DNase B tests.

Transmission ARF results from an interaction of the bacterial agent, human host and environment. GApHS are transmitted from person to person through relatively large droplets, up to a distance of 3 m. ARF develops at a fairly constant rate of 3% following untreated epidemics of strepto-coccal pharyngitis. The attack rate is much lower (<1%) following endemic or sporadic streptococcal infections. Healthy primary school children are commonly found to be carriers of GApHS. Cutaneous streptococcal infection is a frequent precursor of acute nephritis, but has not been shown to cause ARF. Scarlet fever, however, is associated with ARF.

Why only a small percentage of the youthful population develop ARF remains a mystery. ARF patients, as a group, show a higher antibody level to group A streptococ-cal antigens suggesting that repeated exposure to GApHS may precipitate illness. Susceptibility is due to the immunological status of the host, including both humoral and cell-mediated immunity, with a 2% familial incidence of ARF. A larger proportion of children born to rheumatic parents contract the disease. The carditis of RHD might be the result of an autoimmune mechanism developing between group A strepto-coccal somatic components and myocardial and valvular components.

Incubation period of the initial streptococ-cal infection is 1-3 days and 19 days for ARF.

Period of communicability 10-21 days of an acute, untreated streptococcal infection.

Occurrence and distribution ARF/RHD is the commonest form of heart disease in children and young adults in most tropical and developing countries. The peak incidence is 5-15 years, but both primary and recurrent cases can occur in adults. There is neither a sex predilection nor a racial predisposition.

ARF is a disease of lower socioeconomic groups, particularly those massed in the densely populated areas of urban metropolitan centres. It is widespread with a high incidence in South Asia, Pacific Islands, North and South Africa and urban Latin America. It has been estimated that RHD causes 25-40% of all cardiovascular diseases in the developing world.

Control and prevention There is no permanent cure for RHD and the cumulative expense of repeated hospitalization for supportive medical care is a considerable drain on the meagre health resources of developing countries. The only reasonable solution is the prevention of rheumatic fever. ARF is now a rare condition in developed countries due to improved housing, reduction of overcrowding and the provision of adequate health services, so this should be the long-term aim.

Prevention of the first attack (primary prevention) is by proper identification and antibiotic treatment of streptococcal infections. The individual, who has suffered an attack of ARF, is inordinately susceptible to recurrences following subsequent strepto-coccal infection and needs protection (secondary prevention). While primary prevention is preferable, the incidence of ARF as a sequel of streptococcal sore throat is never greater than 3%, even in epidemics. A vast number of infections would need to be treated in order to achieve any meaningful reduction of the total number of sore throats and streptococci are responsible for only 10-20% of them.

Most cases of severe RHD would be prevented by adequate prevention of recurrences of ARF. No matter how mild the first attack of ARF, secondary prevention with intramuscular long-acting benzathine penicillin G 1.2 million units should be given at monthly intervals. Penicillin V or sulpha-

diazine may be used for oral prophylaxis. Regular taking of prophylaxis is essential and compliance is a major problem. Patients with no evidence of cardiac involvement should receive prophylaxis for a minimum of 5 years after the last attack of ARF, while those with carditis should continue until they are 25 years old. Prophylaxis should be continued with penicillin in the pregnant woman.

The emphasis of a prevention programme should be on health education, early diagnosis and treatment of sore throats and the provision of treatment facilities at primary level.

Surveillance In developing strategies, baseline data on streptococcal epidemiology and ARF/RHD prevalence in high-risk groups should be collected. A fully established programme centre would operate a central register, coordinate case-finding surveys, run a system of secondary prophylaxis (especially follow-up) and promote health education. Community control of ARF and RHD is viable only if it is firmly based on existing health services, which are an integral part of the primary health care activities in the country. It is especially relevant to school health services, by screening children and supporting those on secondary prophylaxis.

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