Recurrent Fever in a Healthy 30 Year Old Pregnant Female

A 30-year-old female who is 34 weeks pregnant was admitted with a 3 day history of fever associated with rigors, chills, nausea, and vomiting. Her blood pressure was normal; there was no tachycardia with fever. On admission, her white blood cell count was 4.4 × 103/μL with 3% bands and 74% neutrophils, hemoglobin was 11.0 g/dL, and platelet count was 63 x 109/L Human immunodeficiency virus testing was negative. On day 2 of admission, she developed a fever of 38.8°C resulting in fetal bradycardia, thus prompting an emergent cesarean section. A healthy male infant was delivered. The hematoxylin and eosin stained preparation of the placenta is shown in Figure 1. What is your diagnosis?