Cats swollen stomach

Question
I understand an examination would be necessary to diagnose a disease, but I'm hoping you can give me an idea of what a stray cat might have died from.  She was a stray who lived in my garage in the back yard.  Since I trapped her and had her spayed I know she wasn't pregnant, but one day last week she showed up with a severely swollen stomach.  She really looked bulging with pregnancy.  I didn't notice any other symptoms at all.  Three days later I found her dead.  I'm just wondering if you have any idea at all what might have been wrong with her.  The rest of her family is still living in my garage and I'm concerned whatever she had might be contagious.  Thanks for any clue!

Answer
I would be most concerned about FIP and yes it is contagious....it is fatal.  I would recommend disinfecting everything with bleach just in case.  She may have also be infected with Feline Leukemia or Feline AIDS since she was a stray.  She could of had heart failure with fluid accumulation in the abdomen or an intestinal tumor that led to the fluid.  A severe case of intestinal parasites can lead to fluid accumulation in the belly or result in an intestinal blockage, but not as likely.