What can a fever indicate if no other symptoms are present, such as in a toddler versus in an adult? If the affected person seems otherwise normal, could a worse illness be approaching?

As I understand it a fever is a normal reaction to an infection. It seems that many of the “bugs” people get, don’t do well at higher than what a human is normal temperature. It makes a little bit of sense, but now since we combat bugs with other means, the fever is considered an indication rather than result.