New York City. Returned after twelve days in New Zealand to find I'd contracted Giardiasis, an illness of the small intestine caused by the parasite Giardia lamblia. Curable with a week of antibiotics.
No permanent damage, other than a mark on the top of my wrist from a venipuncture to treat dehydration. The nurse who removed the IV needle said "Wow, a 14 gauge needle — they put a hose in you!"