So, I did an experiment... you know, in the name of science!

I ventured to my personal plains right outside my tavern, wearing nothing but lvl 4 troll armor, a lvl 3 iron banded shield and my trusty abyssal dagger.

Food was fresh blood soup, sausages and a muckshake. That gave me initially 145hp. Which is actually pretty good for just swamp food.

Deathsquito couldn't hit me.

So, if you have an iron banded shield, you should stand a fair chance, once you got swamp food that is. :P

Edit: Your first iron equipment really should be the shield. If it holds off a deathsquito, it will hold off everything in the swamps as well.