A46-year-old woman presents to the emergency room with one day of fever and headache. the day before getting sick she had returned from a 2 week trip to the colombian amazon region. she did not take any travel related vaccines or prophylaxis. her symptoms transiently improved after 3 days of illness but worsened again one day later when she developed high fever, jaundice, petechiae in her extremities, gum bleeding, and multiorgan failure. laboratory test showed a decreased peripheral white blood cell count, elevated liver transaminases and bilirubin, and prolonged coagulation tests. 3 blood smears showed normal red blood cells. which is the most likely cause of her symptoms