HN has very specific rules for this: https://news.ycombinator.com/newsguidelines.html

You don't respond to them at all, flag the comment, and/or email the moderators.

Being snarky does not contribute to the discussion and gets your comments flagged.

So you (high karma user) are recommending that I (low karma user) simply flag (which I can't do) and not respond (leaving no trace) to misinformation?

I should respond to bad info by continuing to lurk. Very smart!

Yes, if you're unable to be polite about it, just don't comment and/or email the moderators. Your comment would have been informative and well-received without the snark.

You were right to call out the other person for trivializing the risks of tick bites, just assume good faith and be kind.