Factor that must be present for disease to occur?

Answer 1

This question is too ambiguous. What kind of disease do you mean?

If you mean infection, you need a pathogen (bacteria, parasite, virus) and the opportunity (the pathogen must get into the right place to cause illness). This doesn't bring into play your immune system which may or may not stop the illness before it begins. For example, a flu virus that gets into a cut cannot make you sick, it needs to be in your respiratory tract/mucus membranes.

Any number of "diseases" exist. Genetic factors, lifestyle factors, health measures (blood pressure, blood sugar, cholesterol, etc) and other things can all play into other diseases. Heart disease, Diabetes, Alzheimer's, etc all have different things that can lead to them (contributing factors).

If this is a general question from a health/science class, chances are the general factors they are looking for are in the chapter you are reading. It may be something like a contributing factor and damage to the system it affects or something to that effect.

Answer 2

1. the host

2.disease agenys

3.environment

Answer 3

The toxins come from two sources from outside with food, air, water, medications, etc. Produced in our body as a result of its own life processes and life processes of bacteria living in it.

Answer 4

by pathogens