Infections & viruses

Infections are what happens when bacteria, viruses, fungi, or parasites get past your defenses and multiply. This section covers the ones people meet most: flu and colds, Lyme disease, mono, whooping cough, stomach bugs, and the infections you can pick up traveling. You will find how each one spreads, the symptoms that separate a nuisance from a real problem, how doctors diagnose them, and what actually treats them, including when antibiotics help and when they do nothing at all. Vaccines and simple hygiene prevent a surprising number of them. See a doctor if a fever is high or will not break, or if symptoms get worse instead of better.