Spiders!! ...or maybe not.

Creepy... I've come to terms with the spiders here in Australia - they're not really as bad as some of the horror pictures that have gone around the internet (millions of them after a flood, large ones eating birds - though I did see a lizard caught in a spider web). But today I felt something itchy on my chest. I go to scratch it and CRUNCH. But... what was it?! There's only a gooey black mess under my fingernail, about 1/4 the size of a pencil eraser. Am I feeling twitchy now? Tingling in my limbs? ok - an hour later, I'm still alive. Oh - and one other time I had a necrotic spot on my leg that was probably a small spider in my clothes. Fortunately, the spot healed rather than grew. Will small doses make me immune? Or will small doses affect my speaking ability, causing me to have a strange accent?