Does anyone know about FIP disease?

I was taking care of 2 stray kitten who were born outside my house. Recently they began ill. I took them to a vet yesterday but one died 3 hrs after I got home. The vet said he "thinks" they have FIP b/c of their symptoms & all the blood work came up neg, except white blood cell count very low. Im trying to keep the other kitty alive, meds, food, water, shelter & praying she makes it. But from what I am reading about this disease, it doesn't look good. Does anyone know about this disease?? Also I have 2 cats, who are mine. They both had their shots when they were suppose to, my concern is could I have brought this disease in the home? I made appts for them to get shots again, does anyone know if this is necessary?

I am so sorry for what you have gone through! Here is an article on the disease (http://www.thecatsite.com/a/fip-in-cats)

FIP sucks, I lost 3 fosters to this desease. There is a very nice support group on Face Book called FIP fighters, you should join them.

Thank u! I actually brought her 2 my vet & he said he doesnt believe she has FIP. HE THINKS its just a virus. There r sooo many! She hasnt thrown up & really wants out of the cage i have her in. She tries 2 eat but it seems like she just cant get it down. I also believe she is really depressed from loosing her sister, they were inseparable.. i let her put of the cage 4 a little bit & she ran around. But i cant let her go loose b/c she's 2 weak & obviously still needs 2 be vaccinated. I would looove 2 bring her in my house but my vet said not 2 b/c of my 2 cats... its so hard trying 2 take care of her & give her all the love she needs from outside but im doing everything i possibly can. I want her 2 live so bad. She's such a sweet baby kitty... its breaking my heart seeing her so sad... thanks again 4 responding

Does she have a stuffed animal or anything out there to cuddle with since she lost her sister.  That might help her a teeny bit, although, naturally, it cannot take her sister's  place .

When does the Vet think she can co-mingle?   Since he doesn't think it's FIP, thank goodness, what is the treatment plan for this "virus"?  Are you force feeding her?