Examples: Influenza, pneumonia, and pneumonic plague.
(iii.) Due to “droplet” infection, as above, or to infected scales from the skin, or to infected discharges from the nose, throat, or ear.
Examples: Measles, scarlet fever, small-pox, chicken-pox, diphtheria.
(iv.) Due to excremental infection through the agency of water, food, flies, fingers, dust, and soil.
Examples: Enteric (typhoid) fever, dysentery, diarrhœa, cholera, worm infections of many kinds.
(v.) Due to inoculation through the bites of insects, or the entry through skin abrasions of the infected excreta or infected crushed tissues of insects rubbed or scratched into these lesions.
Examples: Malaria, yellow fever, tick fever, sleeping sickness, filariasis, relapsing fever, typhus fever, bubonic plague.
(vi.) Due to invasion of the body by insects in their adult or larval stages.
Examples: Chigger, myiasis of various kinds.