I have been lucky so far to nurse two children without an episode of full blown mastitis. I have had many blocked ducts, sometimes to the point that when the clog literally exploded from my nipple, a powerful stream of high pressure milk followed it (along with the most stupid grin you could ever imagine from me as the pain drained away).

So does mastitis ever occur without the warning signs of a blocked duct?

I think the warning signs are pretty clear from my experience. I don't ever want to go through that pain again. It was awful, I can relate to that stupid grin :)

From what I've always understood they aren't necessarily connected as mastitis isn't inclusive of a blocked duct, but once the duct is blocked mastitis can set in. Mastitis is the infection which is accompanied by a fever and pain and swelling and often a red mark thats wedge shaped and cleared up by antibiotics typically (if you go to the doctor at least). If you'd had a blocked duct it mastitis it is more likely to happen again though :(

Yes, the blocked ducts recurred rather frequently, but they were easy enough to deal with. Between warm compresses and rather a lot of grit my teeth and squeeze out the blockage, they were soon gone.

I've had it twice since my son was born, both during times of extreme stress. It was like, in the morning I woke up with a blocked duct and by noontime I had fever, chills, etc (despite trying to work through the blockage in the morning). So mine came on very fast, it wasn't like I had a block, and then a week later had an infection.