How does good hygiene help stop the spread of disease?

Iv found that websites such as HSC online and Excel HSC (in google books) are reli great resources and rarely ever fail to give an answer (especially Excel HSC).

HSC online - Just type in 'HSC online' in google.

Excel HSC - go to google and up the top where it says web, images, Video etc click on more than book. It will offer a range of books for different subjects. Just choose the Biology one.

Hope this helped a lil =)

(Im actually doing this question for a biology portfolio assignment right now lol)