How to respectfully tell MIL that she (once again) got me sick.

This past Sunday DH and I stopped by IL’s house on our way out of town from visiting my family. I remain LC with all of them but DH speaks with them daily. When we arrived, MIL informs me she is ill so she doesn’t want to hug or be too close to us. I was a bit frustrated because this is the second time in the past 3 months in which she has been sick but hasn’t told DH or I until we are already at their home. Last time she had the flu and I ended up getting it for 14 days and had to go to the urgent care.

I did my best to be friendly (while also being concerned for our health) during our visit. MIL had a social event she wanted to go to that evening. She asked me what she should do, to which I said, “Think about it as if you were in their shoes, would you want to go to a house where someone was sick?” to which she replied, “Well, personally I don’t care if someone is sick!! I’d rather see them, and get sick— if that means I got to spend time with them.”

So instead of cancelling her plans she called the host and told them “I’m not feeling well but it’s up to you whether or not you’ll have me”. Which IMO is extremely disrespectful and manipulative. They texted her, “We trust you will make the right decision.” … so she went.

Now, three days later, I’m coming down with the same symptoms she had. How do I respectfully tell her she gave me her illness? Do I even bother?

UPDATE: thank you all so much for the advice and support — and constructive criticism. I texted her a few minutes ago this, “Hi, I hope you’re feeling better. Unfortunately it looks like I’ve come down with your cold, so we’ll want to be more careful next time we visit if you or anyone else is under the weather, since it seems that my immune system is susceptible to colds and flus. Thanks!”

Clarification: I want to remain respectful because I don’t want to stoop to their level, have them twist what I say to make them look like a victim, or cause unnecessary drama. If it can be said in a factual and respectful way, I’d rather do that.