Final answer:
Young children have the highest carriage rate of S. pneumoniae, with 30-70% of children carrying the bacterium. S. pneumoniae can cause various diseases in susceptible individuals, such as meningitis and septicemia.
Step-by-step explanation:
The population with the highest carriage rate of S.pneumoniae is young children. According to research, S.pneumoniae can be found in the microbiota of the pharynx of 30-70% of young children, whereas it is found in fewer than 5% of healthy adults. Although it may be present without symptoms, this bacterium can cause meningitis, septicemia, and other diseases in susceptible individuals such as newborns, the elderly, and those with immunodeficiency.