Linked from
The 11 pages that link to Intermediate host, each with the reason it gives.
CestodaRelated: Many cestodes require one or more intermediate hosts to complete development.
Parasitic diseaseRelated: Many parasites require an intermediate host to complete their life cycles.
HelminthologyRelated: Many helminths require one or more intermediate hosts to complete development.
HelminthiasisRelated: Flukes and many tapeworms require other species to complete their life cycles.
CoenurosisRelated: Sheep and other hosts acquire infection by ingesting tapeworm eggs.