A parasite, such as a louse or an intestinal worm, that is visible to the naked eye.
Those parasites (e.g., helminths, arthropods) that do not multiply within their definitive host, cycling instead through transmission stages (eggs and larvae), which pass to the outside. Immune responses evoked by macroparasites are transient and depend on the parasite load; the key epidemiologic measure is the number of parasites per host.
Infectious disease A parasite–eg, helminths, arthropods–which does not multiply in its definitive host, cycling instead through transmission stages–eggs and larvae–which pass into the external environment; immune responses evoked by macroparasites are transient and depend on the parasite load. Cf Microparasite.
And, of course, they will have to dispose of thugs who used to have spears but will now have cruise missiles and H-bombs -- that is, the macro-parasites that have infected humanity ever since the first farmers realized that having crops took away the option of running away into the forest.