"Imperialism was a creed that could contaminate the British people?

What does this quote mean? I had to put this quote in the question, as saying"what does this line meaan" might not attract askers. Now that i hav your attention... I heard this line in some 19th centruy doentery about context of britain at the time, since im doing jane austen and stuff at school. Does anyone have any idea what this quote is about and what imperialism is? Is australia under imperialism at the moment?