Virulence factors are specific components or characteristics that enable a pathogen (such as bacteria, viruses, fungi, or parasites) to cause disease in its host. These factors can include the ability to produce toxins, adhere to host cells, evade the immune system, and invade tissues. The presence of these virulence factors determines the severity and outcome of an infection, with more potent pathogens having a higher number or effectiveness of these factors. Understanding virulence factors is crucial for developing strategies to combat infectious diseases.