The Unseen Engine: Understanding Human Parasitic Infections, Systemic Pathology, and Evidence-Based Elimination ​While often dismissed as a third-world concern, human parasitic infections are a documented global reality. A parasite is an organism that lives on or inside a host organism, deriving nutrients at the host's expense while causing tissue damage, chronic mucosal inflammation, and severe metabolic disruption. ​In clinical medicine, human parasites are categorized into