What to do if I have to do this leaflet for years 1+2 about diseases, like sars and swine flu. How are they transmitted?

Leaflet. If asked to do a leaflet about a medical topic that is not in an area of yoru expertise, it would be wise to consult an authoritative source like the CDC website for information. The CDC does a good job in making medical information available in a way that everyone can understand it.