Cases occur in infants, the elderly and certain high-risk groups.
The disease occurs throughout the world. It is more common in the winter and spring months, in babies, the elderly, lower socioeconomic groups and developing countries. In Canada and the United States most cases occur sporadically, but outbreaks can occur in closed populations. Fever, vomiting and convulsions may be the first symptoms in young children. A person is capable of passing the infection on as long as nasal and throat discharges contain pneumococci in large numbers.