Question about Cat ALLERGIES

[grandma-w-cat]

I'm pretty sure our granddaughter is allergic to cats, but I have a question that someone who knows about cat allergies may be able to answer. When an (infant) who is allergic goes into a house with a cat and has symptoms, shouldn't the symptoms go away after they go home and take a bath? Her clothes were changed and no blankets or toys went home with her, although her stroller and infant car seat were in the house with the cat (they probably were not washed). Is it normal for severe symptoms to persist days later? Could she have caught a cold from being exposed?