Research overview: land-to-sea flow of Toxoplasma and marine mammal disease

The discovery that a terrestrial cat parasite kills marine mammals reshaped understanding of how pathogens cross ecosystem boundaries. This overview synthesizes research on the flow of Toxoplasma oocysts from land into coastal waters, where filter-feeding invertebrates concentrate them and pass infection up to sea otters, seals and dolphins. It examines the roles of domestic and wild felids as oocyst sources, the importance of freshwater runoff and watershed condition, and the use of marine mammals as sentinels of this contamination. The synthesis connects feline parasitology, oceanography and conservation. It aims to help readers grasp the remarkable journey of a felid-shed parasite from cat feces to the open sea, and why protecting marine wildlife from toxoplasmosis ultimately depends on managing terrestrial cat populations and coastal water quality.