Epidemiology for the Health Professions

Epidemiology of Infectious Diseases: Causative Agent (Page 1 of 7)

There are six basic categories of biological etiologic agents or pathogens: protozoa, metazoa, bacteria, virus, fungus, and rickettsia.
  1. Protozoa -- unicellular animals that cause malaria, giardiasis, trypanosomiasis, leishmaniasis, amoebic dysentery, trichomoniasis, and pneumocystis carinii pneumonia. Many are vector-borne.

  2. Metazoa -- multicellular animal parasites that cause diseases such as trichinosis, hookworm, schistosomiasis. Usually have an extra-human developmental stage and therefore are not transmissable from person to person.