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You are evaluating a 10 year old patient who had a bone marrow transplant 2 months ago. The patient is presenting with low-grade fever, a maculopapular rash on the nape of the neck, shoulders, palms, and soles as well as nausea, vomiting, and diarrhea. The patient owns a cat but is not involved in caring for it and does not have it sleep with him. 

Which of the following diagnoses are you most concerned about?