infectious disease

(noun)

Infectious diseases, also known as transmissible diseases or communicable diseases comprise of clinically evident illness (i.e., characteristic medical signs and/or symptoms of disease) resulting from the infection, presence and growth of pathogenic biological agents in an individual host organism. In certain cases, infectious diseases may be asymptomatic for much or even all of their course in a given host. In the latter case, the disease may only be defined as a "disease" (which by definition means an illness) in hosts who secondarily become ill after contact with an asymptomatic carrier. An infection is not synonymous with an infectious disease, as some infections do not cause illness in a host.

Related Terms

Examples of infectious disease in the following topics:

  • Vaccination

    • Vaccination is a proven way to prevent and even eradicate widespread outbreaks of life-threatening infectious diseases.
    • Active immunity to diseases can be acquired by natural exposure (in response to actually contracting an infectious disease) or it may be acquired intentionally, via the administration of an antigen, commonly known as vaccination .
    • Even today, the risk of contracting some of these infectious diseases, like measles and chicken pox, can have devastating, long-term complications, like blindness.
    • Certain infectious diseases, such as Smallpox, have been completely eradicated.
    • By these vaccinated children not contracting these diseases, their parents, grandparents, friends and relatives (not vaccinated against these diseases themselves) will also be protected.

  • Development of New Vaccines

    • New vaccines are being developed to control recent infectious disease epidemics and cancers.
    • Even in the poorest countries, immunizations have been able to achieve significant progress in disease control.
    • A number of new vaccines with major potential for controlling infectious diseases have just been licensed or are at advanced stages of development.
    • The World Health Organization (WHO) facilitates the development of vaccines against infectious diseases of major public health importance, helps improve existing immunization technologies, and ensures that these advances are made available to the people who need them the most.
    • Describe how new vaccines are being developed to help eradicate several infectious global diseases

  • Emerging and Reemerging Infectious Diseases

    • An emerging infectious disease is a disease with a rate of incidence that has increased in the past 20 years, and could increase in the near future.
    • An emerging infectious disease (EID) is an infectious disease whose incidence has increased in the past 20 years, and could increase in the near future.
    • Of growing concern are adverse synergistic interactions between emerging diseases and other infectious and non-infectious conditions leading to the development of novel syndemics.
    • Influenza, commonly known as the flu, is an infectious disease of birds and mammals caused by RNA viruses of the family Orthomyxoviridae, the influenza viruses.
    • Tuberculosis, MTB, or TB (short for tubercle bacillus) is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis.

  • The Diagnostic Scheme

    • Diagnosis of infectious disease sometimes involves identifying an infectious agent either directly or indirectly.
    • Diagnosis of infectious disease sometimes involves identifying an infectious agent either directly or indirectly.
    • In practice most minor infectious diseases such as warts, cutaneous abscesses, respiratory system infections and diarrheal diseases are diagnosed by their clinical presentation.
    • Microbiological culture is a principal tool used to diagnose infectious disease.
    • Second, an infectious agent must grow within the human body to cause disease; essentially it must amplify its own nucleic acids in order to cause a disease.

  • Predisposing Factors

    • The spread and severity of infectious disease is influenced by many predisposing factors.
    • The spread and severity of infectious disease is influenced by many predisposing factors.
    • Some of these are more general and apply to many infectious agents, while others are disease specific.
    • The most common infectious agent is Pseudomonas aeruginosa.
    • Overall health is a very important factor in preventing disease.

  • Infectious Disease Transmission

    • Defining the means of transmission plays an important part in understanding the biology of an infectious agent and in addressing the disease it causes.
    • Some infectious agents may be spread as a result of contact with a contaminated, inanimate object (known as a fomite), such as a coin passed from one person to another, while other diseases penetrate the skin directly.
    • Transmission of infectious diseases may also involve a vector.
    • A common strategy used to control vector borne infectious diseases is to interrupt the life cycle of a pathogen by killing the vector.
    • Washing hands with soap and clean water (for at least 20 seconds) is the most effective measure to prevent the spread of infectious diseases.

  • Technology and New Infectious Agents

    • Technology aids in the identification of new infectious agents, but it also contributes to the emergence of new diseases.
    • Looking back at past epidemics or outbreaks caused by previously unknown infectious agents, we realize that identification and characterization of a new infectious agent can take years, decades, or even centuries.
    • The effects of new technology on the environment are related to the emergence of many infectious diseases.
    • Factors related to the emergence of infectious diseases such as Legionnaire disease and hemolytic uremic syndrome include changing technologies: air conditioning systems and mass food production, respectively.
    • Give examples demonstrating the positive and negative impacts technology has had on new infectious agents

  • Exceptions to Koch's Postulates

    • Even in Koch's time, it was recognized that infectious agents could be responsible for disease without fulfilling all of the postulates.
    • Even in Koch's time, it was recognized that some infectious agents were clearly responsible for disease, even though they did not fulfill all of the postulates.
    • Currently, a number of infectious agents are accepted as the cause of diseases despite their not fulfilling all of Koch's postulates.
    • Asymptomatic or subclinical infection carriers are now known to be a common feature of many infectious diseases, especially viruses such as polio, herpes simplex, HIV, and hepatitis C.
    • The third postulate specifies "should", not "must", because as Koch himself proved in regard to both tuberculosis and cholera, that not all organisms exposed to an infectious agent will acquire the infection.

  • Intracellular Pathogens

    • A pathogen or infectious agent is a microorganism such as a virus, bacterium, prion, or fungus that causes disease in its host.
    • Their theory was developed to explain the discovery that the mysterious infectious agent causing the diseases scrapie and Creutzfeldt–Jakob disease resisted ionizing radiation.
    • A pathogen or infectious agent is a microorganism such as a virus, bacterium, prion, or fungus that causes disease in its host.
    • Although the vast majority of bacteria are harmless or beneficial, a few pathogenic bacteria can cause infectious diseases.
    • These abnormally-folded proteins are found characteristically in some diseases such as scrapie, bovine spongiform encephalopathy (mad cow disease), and Creutzfeldt–Jakob disease.

  • Diagnosing Microbial Diseases

    • The process of identifying infectious diseases is complex and requires identification of the agent through direct or indirect means.
    • The first tool in diagnosing microbial disease is microbial cultures.
    • It is critical to isolate the infectious agent in a pure culture containing only the infectious bacteria.
    • An additional tool utilized for microbial disease diagnosis is microscopy.
    • Biochemical tests are also used to help in microbial disease diagnosis.