From Terra Nova Wiki
Trichomonas Sastre is a parasite in Terra Nova.
Trichomonas Sastre can cause heart lesions in Slashers but in humans they attack the central nerve system and burrow their way into the brain stem, slowly and very painfully killing the afflicted. (Resistance)
When Jim Shannon was detained by Lucas Taylor, Dr. Elisabeth Shannon deceived Weaver into believing that she had switched his Antihistamine injection with a dose of half a million Trichomonas larvae that would kill him if he did not receive an Anti-parasitic injection. (Resistance)