Melaleuca alternifolia (tea tree) oil and its monoterpene constituents in treating protozoan and helminthic infections

•Australian tea tree oil display a range of biological and pharmacological properties.•Tea tree oil and its 15 major constituents have effects on parasitic infections.•The parasites include protozoa, nematodes, cestodes, and monogenean parasites.•Prolonged survival or curative effect on protozoan infections in treated animals.•Helminthic burden was reduced or controlled in treated animals.