{Article} SciTechMed: Vector Borne Disease and Mosquito Magnet

• In epidemiology, a vector is any agent (person, animal or microorganism) that carries and transmits an infectious pathogen into another living organism.
• A vector-borne disease is one in which the pathogenic microorganism is transmitted from an infected individual to another individual by an arthropod or other agent, sometimes with other animals serving as intermediary hosts. The transmission depends upon the attributes and requirements of at least three different living organisms: [1.] the pathologic agent, either a virus, protozoa, bacteria, or helminth worm); [2.] the vector, which are commonly arthropods such as ticks or mosquitoes; [3.] the human host. In addition, intermediary hosts such as domesticated and/or wild animals often serve as a reservoir for the pathogen until susceptible human populations are exposed. Nearly half of the world's population is infected by vector-borne diseases, resulting in high morbidity and mortality, with the overwhelming impact in developing countries located in tropical and subtropical areas and relatively rare in temperate zones.
• Most commonly known biological vectors are arthropods but many domestic animals too are important vectors or asymptomatic carriers of parasites and pathogens that attack humans or other animals. Arthropods form a major group of disease vectors with mosquitoes, flies, sand flies, lice, fleas, ticks and mites transmitting a huge number of diseases. Many such vectors are haematophagous, which feed on blood at some or all stages of their lives. When the insects blood feed, the parasite enters the blood stream of the host. This can happen in different ways.
• The concept of disease vectors has some commonality with certain other concepts in medicine and veterinary science; it is worth comparing vectoring, zoonosis and carrier for perspective. Zoonosis sometimes arises from purely adventitious or non-systematic transport of the infectious agent. For example a housefly or a dog might accidentally, but routinely, carry the pathogens of typhoid or cholera in external dirt without being in any special way adapted to such a function. Technically such a process amounts to vectoring, and such vectors are important in practice, though they are logically similar to airborne disease and waterborne diseases.