This case study follows “Molly,” a volunteer with an aid organization conducting annual medical mission trips to Cameroon, Africa.  On their most recent trip, her team was exposed to a local outbreak of listeriosis, and Molly was prophylactically treated with ampicillin. She reacted poorly to the antibiotic and sought medical attention upon returning home. On a previous trip, Molly had contracted a different disease, ascariasis, although she was completely unaware of this. The parasitic worm had previously caused her only mild discomfort, probably due to a low infectious load, but the empirical treatment with ampicillin had made her symptoms worse. Once properly diagnosed, thanks to a thorough blood panel ordered by her physician, she discontinued the antibiotic and was given an antihelminthic, albendazole, instead. Students are asked to critically analyze the course of her illness through blood panels, drug information, doctor’s diagnoses, and pathogen profiles. The case was developed for students in a school of pharmacy but would be appropriate for nursing, medical students, or graduate students in a program such as pharmaceutics or pharmaceutical sciences.