| Criteria | Marks |
|---|
| Explains how the mode of transmission of pathogens affects the spread of diseases | 3 |
| Outlines how one mode of transmission of a pathogen affects the spread a disease<br>OR<br>Identifies modes of transmission of pathogens | 2 |
| Provides some relevant information | 1 |
Sample answer:
Some diseases are spread easily by the pathogen passing between people in droplets in the air, eg influenza virus, and therefore the rates of infection are high in populated areas.
If an intermediate host or a vector is required then the spread of the disease may be slower depending on the presence of the vector.