Review Question - QID 213607

A 52-year-old man presents to his primary care physician with a 3-week history of slowly waxing and waning fevers. In general, he describes these fevers as fairly low but sometimes accompanied by chills. He says that he has also been experiencing headaches, nausea, and vomiting since he returned from a vacation to Peru. On presentation, he is found to have hepatosplenomegaly, but no rashes or skin lesions. He denies having any shortness of breath or chest pain. Gram stain reveals gram-negative coccobacilli, and he is started on a course of doxycycline. Which of the following was the most likely method by which this patient acquired this infection?