Streptococcal disease and the host-parasite relationship

Abstract

Streptococcal evolution has been shaped by human history, social change and microbial selection. Streptococci with pathogenicity for people likely diversified within the last 5-10,000 years, jumping from animal hosts to infect the larger aggregations of people seen in towns and cities following the rise of agriculture. Streptococci are subject to continuing selection through changes in population immunity, hygiene, living conditions, medical interventions, and family size. Such selective effects can account, in part at least, for the virtual disappearance of scarlet fever, for changes in the prevalence and virulence of strains, and for the greatly reduced rates of rheumatic fever in affluent..