Biological Vectors and Infectious Disease - More Real World Science on Harmony Square

Using incredible videography, photos, animation and graphics, this information-packed video introduces students to biological vectors. Viewers will learn that biological vectors carry and transmit disease that affect plants, animals and humans.

The program explores various types of diseases spread by vectors including, Zika, Lyme Disease, Malaria, Dengue and Yellow Fever. The video vividly demonstrates how a mosquito sucks blood from a human and then explains how a pathogen is transmitted.

Students will learn how scientists who study insects and infectious diseases can use the information they gather to help control and prevent the transmission of vector-borne diseases around the world.

By viewing this video, discussing the concepts that are presented, and participating in the accompanying activities, students will be able to:
• Learn that biological vectors are animals that carry and transmit disease
• Name the types of animals that can become vectors
• Understand how a mosquito transmits diseases
• Recognize that scientists develop ways to prevent and control the spread of vector-borne diseases
• Understand the natural history of vectors
• Realize that mosquitoes are the most dangerous animal on the planet

Infection is the invasion of an organism's body tissues by disease-causing agents, their multiplication, and the reaction of host tissues to the infectious agents and the toxins they produce. Infectious disease, also known as transmissible disease or communicable disease, is illness resulting from an infection.

Infections are caused by infectious agents (pathogens). Hosts can fight infections using their immune system. Mammalian hosts react to infections with an innate response, often involving inflammation, followed by an adaptive response.

Specific medications used to treat infections include antibiotics, antivirals, anti-fungals, antiprotozoals, and antihelminthics. Infectious diseases resulted in 9.2 million deaths in 2013 (about 17% of all deaths). The branch of medicine that focuses on infections is referred to as infectious disease.

In epidemiology, a disease vector is any agent which carries and transmits an infectious pathogen into another living organism; most agents regarded as vectors are organisms, such as intermediate parasites or microbes, but it could be an inanimate medium of infection such as dust particles.

Arthropods form a major group of pathogen vectors with mosquitoes, flies, sand flies, lice, fleas, ticks, and mites transmitting a huge number of pathogens. Many such vectors are haematophagous, which feed on blood at some or all stages of their lives. When the insects blood feed, the pathogen enters the blood stream of the host. This can happen in different ways.

The Anopheles mosquito, a vector for malaria, filariasis, and various arthropod-borne-viruses (arboviruses), inserts its delicate mouthpart under the skin and feeds on its host's blood. The parasites the mosquito carries are usually located in its salivary glands (used by mosquitoes to anaesthetise the host). Therefore, the parasites are transmitted directly into the host's blood stream. Pool feeders such as the sand fly and black fly, vectors for pathogens causing leishmaniasis and onchocerciasis respectively, will chew a well in the host's skin, forming a small pool of blood from which they feed. Leishmania parasites then infect the host through the saliva of the sand fly. Onchocerca force their own way out of the insect's head into the pool of blood.

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.

Many plant pests that seriously damage important crops depend on other plants, often weeds, to harbor or vector them; the distinction is not always clear. In the case of Puccinia graminis for example, Berberis and related genera act as alternate hosts in a cycle of infection of grain.

defenses of the hosts they infect. The appearance and severity of disease resulting from any pathogen, depends upon the ability of that pathogen to damage the host as well as the ability of the host to resist the pathogen. However a host's immune system can also cause damage to the host itself in an attempt to control the infection. Clinicians therefore classify infectious microorganisms or microbes according to the status of host defenses - either as primary pathogens or as opportunistic pathogens.