Theory of virulence

Virulence is when bacteria or viruses make us sick. The theory of virulence explains why some bacteria or viruses make us sick and how they cause us to become ill.

Bacteria and viruses can spread from one person to another, or from animal to person, and when they come into contact with our bodies, they can cause us to become ill. But some bacteria and viruses don't make us ill at all. The theory of virulence tells us why this is.

The theory of virulence says that some bacteria and viruses can make us ill because they have something called "virulence factors", which make them more dangerous than other bacteria and viruses. These virulence factors can be resistant to our body's defenses, meaning they can make us more likely to get sick. They can also make it harder for our body to fight off the bacteria or virus, meaning our body may struggle to get better.

So, the theory of virulence helps us understand why some bacteria and viruses make us sick and why some don't. With this understanding, we can better protect ourselves against dangerous bacteria and viruses and, hopefully, stay healthy.