Vector (biology) facts for kids

A mosquito shortly after obtaining blood from a human (note the droplet of blood plasma being expelled as the mosquito squeezes out excess water). Mosquitos are a vector for several diseases, including malaria.

In epidemiology, a disease vector is any living agent that carries and transmits an infectious pathogen to another living organism. Agents regarded as vectors are organisms, such as parasites or microbes. The first major discovery of a disease vector came from Ronald Ross in 1897, who discovered the malaria pathogen when he dissected a mosquito.

Many factors affect the incidence of vector-borne diseases. These factors include animals hosting the disease, vectors, and people.

Insects

The deer tick, a vector for Lyme disease pathogens.

Mosquitoes, flies, sand flies, lice, fleas, ticks, and mites transmit a huge number of pathogens. Many such vectors are |feed on blood at some or all stages of their lives. When the insects feed on blood, the pathogen enters the blood stream of the host. This can happen in different ways.

The Anopheles mosquito is a vector for malaria, filariasis, and various arthropod-borne-viruses (arboviruses). When it inserts its delicate mouthpart under the skin and feeds on its host's blood, the parasites located in its salivary glands are transmitted directly into the host's blood stream.

Triatomine bugs are responsible for the transmission of a trypanosome, Trypanosoma cruzi, which causes Chagas Disease. The Triatomine bugs defecate during feeding and the excrement contains the parasites, which are accidentally smeared into the open wound by the host responding to pain and irritation from the bite.

Plants and fungi

Some plants and fungi act as vectors for various pathogens. For example, the big-vein disease of lettuce was long thought to be caused by a member of the fungal division Chytridiomycota, namely Olpidium brassicae. Eventually, however, the disease was shown to be viral. Later it transpired that the virus was transmitted by the zoospores of the fungus and also survived in the resting spores. Since then, many other fungi in the Chytridiomycota have been shown to vector plant viruses.

Mammals

Rabies is transmitted through exposure to the saliva or brain tissue of an infected animal. Any warm-blooded animal can carry rabies, but the most common vectors are dogs, skunks, raccoons, and bats.

World Health Organization and vector-borne disease

The World Health Organization (WHO) states that control and prevention of vector-borne diseases are emphasizing "Integrated Vector Management (IVM)", which is an approach that looks at the links between health and environment, optimizing benefits to both.

In April 2014, WHO launched a campaign called “Small bite, big threat” to educate people about vector-borne illnesses. WHO issued reports indicating that vector-borne illnesses affect poor people, especially people living in areas that do not have adequate levels of sanitation, drinking water and housing.

Humans

Figure 1. This figure shows how the Flavivirus is carried by mosquitos in the West Nile Virus and Dengue fever. The mosquito would be considered a disease vector.

Several articles, recent to early 2014, warn that human activities are spreading vector-borne zoonotic diseases.

Examples of vector-borne zoonotic diseases include:

• Lyme disease
• Plague
• West Nile virus

There are several species of Thrips that act as vectors for over 20 viruses, especially Tospoviruses, and cause all sorts of plant diseases.

Humans can also be vectors for Tobacco mosaic virus, physically transmitting the virus with their hands from plant to plant.

See also

In Spanish: Vector (desambiguación) para niños