Epidemiology of Group A Streptococcal Pharyngitis & Impetigo: A Cross-Sectional & Follow up Study in a Rural Community of Northern India (Report)
Streptococcus pyogenes, i.e. Lancefield group ‘A’ beta haemolytic Streptococcus (GAS) is capable of causing a wide variety of diseases, such as scarlet fever, pharyngitis, impetigo, acute rheumatic fever (ARF), rheumatic heart disease (RHD), glomerulonephritis, necrotizing fascitis and toxic shock syndrome, etc. The global burden of group A streptococcal diseases is an estimated 616 million GAS pharyngitis cases per year (1). Epidemiological data from developing countries are scarce. Prevalence of GAS pharyngitis and carriage in asymptomatic children in different countries varies from 9 to 34.1 per cent (2-6). In India, prevalence of GAS pharyngitis ranged from 4.2 to 13.7 per cent (7-11). The incidence of GAS culture positive pharyngitis among 5-15 yr old urban slum children near Chandigarh in northern India is 0.95 episodes per child per year, as compared to 0.13 episodes per child year in urban Melbourne (11,12). It is estimated that 0.3 per cent of the streptococcal sore throat episodes in endemic situation and 3 per cent during epidemics develop into ARF (13,14); and 60 per cent of the ARF episodes may progress to damage the heart valves causing RHD. Although ARF/ RHD has declined in many parts of the world, but continues to be a major public health problem causing significant cardiovascular morbidity and mortality in India (15). Strain prevalence rather than the innate virulence potential is considered to be a major factor for the observed increase in serious group A streptococcal infections (16). The epidemiological picture of streptococcal infections in India is quite different from that of the developed countries, suggesting that may be some serotypes are much more common than others within a population in different geographical locations (17). In the absence of GAS type distribution data, true propensity of any M type to cause a specific clinical manifestation still remains controversial. Moreover, the eventual introduction of vaccines, especially those based on multiple M protein protective epitopes, requires better understanding of group A streptococcal pharyngitis. Hence, we studied GAS sore throat and skin sores in 5-15 yr old school children, and carried out emm typing of the GAS isolates.