infectious disease

(noun)

Illness caused by introduction of a pathogen or parasite into the body via contact with a transmitting agent such as vector organism or an infected person.

Related Terms

Examples of infectious disease in the following topics:

  • Overcoming Density-Dependent Regulation

    • Public health, sanitation, and the use of antibiotics and vaccines have lessened the impact of infectious disease on human populations.
    • Today, however, the plague and other infectious diseases have much less of an impact.
    • Through vaccination programs, better nutrition, and vector control (carriers of disease), international agencies have significantly reduced the global infectious disease burden.
    • Developing countries have also made advances in curbing mortality from infectious disease.
    • Through changes in economic status, as in Brazil, as well as global disease control efforts, human population growth today is less limited by infectious disease than has been the case historically.

  • History of Bacterial Diseases

    • There are records about infectious diseases as far back as 3000 B.C.E.
    • In the 21st century, infectious diseases remain among the leading causes of death worldwide, despite advances made in medical research and treatments in recent decades.
    • It has been estimated that up to 90 percent of Native Americans died from infectious diseases after the arrival of Europeans, making conquest of the New World a foregone conclusion.
    • Approximately 75 percent of recently-emerging infectious diseases affecting humans are zoonotic diseases.
    • The war against infectious diseases has no foreseeable end.

  • Plant Defenses Against Pathogens

    • Pathogens are agents of disease.
    • These infectious microorganisms, such as fungi, bacteria, and nematodes, live off of the plant and damage its tissues.

  • Discovery and Detection of Viruses

    • Viruses are infectious particles about 100 times smaller than bacteria and can only be observed by electron microscopy.
    • In 1886, Adolph Meyer demonstrated that a disease of tobacco plants, tobacco mosaic disease, could be transferred from a diseased plant to a healthy one via liquid plant extracts.
    • In 1892, Dmitri Ivanowski showed that this disease could be transmitted in this way even after the Chamberland-Pasteur filter had removed all viable bacteria from the extract.
    • Still, it was many years before it was proven that these "filterable" infectious agents were not simply very small bacteria, but were a new type of tiny, disease-causing particle.
    • These individual virus particles are the infectious form of a virus outside the host cell.

  • Prions and Viroids

    • Prions are infectious particles that contain no nucleic acids, and viroids are small plant pathogens that do not encode proteins.
    • Fatal neurodegenerative diseases, such as kuru in humans and bovine spongiform encephalopathy (BSE) in cattle (commonly known as "mad cow disease"), were shown to be transmitted by prions.
    • Although a rare disease, individuals that acquire CJD are difficult to treat.
    • PrP exists in two forms: PrPc, the normal form of the protein, and PrPsc, the infectious form .
    • Human diseases caused by viroids have yet to be identified.

  • Protists as Human Pathogens

    • Many protists exist as parasites that infect and cause diseases in their hosts.
    • A pathogen is anything that causes disease.
    • Trypanosoma brucei, the parasite that is responsible for African sleeping sickness, confounds the human immune system by changing its thick layer of surface glycoproteins with each infectious cycle .
    • During epidemic periods, mortality from the disease can be high.
    • In Latin America, another species, T. cruzi, is responsible for Chagas disease.

  • Innate Immune Response

    • The immune system serves to defend against pathogens: microorganisms that attempt to invade and cause disease in a host.
    • The environment surrounding all of us consists of numerous pathogens: agents (usually microorganisms) that cause disease(s) in their hosts.
    • Pathogens, which include bacteria, protists, fungi, and other infectious organisms, can be found in food and water, on surfaces, and in the air.
    • They are composed of an extremely-diverse array of specialized cells and soluble molecules that coordinate a rapid, flexible defense system capable of providing protection from a majority of these disease agents .

  • White Blood Cells

    • Natural killer cells attack a variety of infectious microbes and certain tumor cells.
    • The presence of HIV can remain unrecognized for an extensive period of time before full disease symptoms develop.

  • Neurodegenerative Disorders

    • Alzheimer's disease and Parkinson's disease are both neurodegenerative disorders characterized by loss of nervous system functioning.
    • Neurodegenerative disorders include Huntington's disease, amyotrophic lateral sclerosis (ALS), Alzheimer's disease, other dementia disorders, and Parkinson's disease.
    • Parkinson's disease is also a neurodegenerative disease.
    • The disease probably results from a combination of genetic and environmental factors, similar to Alzheimer's disease .
    • Distinguish between the neurodegenerative disorders of Alzheimer's disease and Parkinson's disease

  • Steps of Virus Infections

    • The symptoms of viral diseases result from the immune response to the virus, which attempts to control and eliminate the virus from the body and from cell damage caused by the virus.
    • This approach has led to the development of a variety of drugs used to treat HIV and has been effective at reducing the number of infectious virions (copies of viral RNA) in the blood to non-detectable levels in many HIV-infected individuals.