Insects and Vector-Borne Diseases

Insects or other arthropods, such as ticks and mites, that transmit disease-causing agents (pathogens) are called vectors.
A person who gets bitten by a vector and gets sick could have a vector-borne disease.
Examples of vectors that might transmit disease are mosquitoes, black flies, biting midges, sand flies, horse and deer flies, tsetse flies, triatomine bugs, lice, fleas, ticks, and mites.

Among the variety of arthropods that transmit pathogens to people and animals, mosquitoes and ticks are the most important.
Viruses and bacteria (including rickettsiae) are the most diverse groups of pathogens transmitted by arthropods, followed by protozoa and filarial nematodes.
A virus that is transmitted by insects or other arthropods is usually referred to as an arbovirus (an acronym for arthropod-borne virus).
Pathogens can be transmitted by arthropods in two basic ways, biological or mechanical.
- In biological transmission, the pathogens undergo development or reproduction in the arthropod host.
- In mechanical transmission, the pathogens are transmitted via contaminated appendages (usually mouthparts) or regurgitation of an infectious blood meal.
Refer to CDC’s A−Z Index of Vector-Borne Diseases and Conditions for information about vector-borne diseases, conditions, and other topics.