An elderly woman with a fever after traveling

A 74-year-old woman with a history of hypertension, left bundle branch block, apparently cured invasive melanoma, and a remote history of Lyme disease presented to the Emergency Department. She complained of daily fevers up to 104 °F (40 °C), rigors, and sweats for a week. She reported a dry cough without shortness of breath, sinus congestion, headache, abdominal pain, nausea, vomiting, diarrhea, dysuria, or urinary frequency. She resided in Illinois and had vacation homes in the Northwestern United States and coastal New England. She had traveled extensively during the last year, in the USA, Europe, Africa, and South America. She visited South Africa approximately 8 months earlier; she went to Kruger National Park and participated in game drives and walking safaris. She had visited Kenya 1 year before. She had not taken malaria prophylaxis for any of those trips. She denied any recent sick contacts or insect bites.