Infectious Diseases Glossary
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- Active immunization – Active immunization is the process of stimulating the immune system to produce antibodies against a specific pathogen.
- Acute Febrile Illness (AFI) – AFI is the medical term for a rapid onset of fever and symptoms such as headache, diarrhea, chills or muscle…
- Adenovirus – An adenovirus is a common virus that causes a range of diseases, including a cold, sore throat, bronchitis, pneumonia, diarrhea,…
- Adverse event severity – The severity of adverse events in clinical trials refers to how intense the event is, typically classified as mild, moderate, severe, or potentially life-threatening.
- Adverse event vs. side effect – Any incident that occurs following a drug, vaccine, surgery, procedure or other medical intervention. If the adverse effect was actually…
- Adverse events – Adverse events are any negative outcomes that occur following administration of a pharmaceutical product, such as a drug or vaccine, or after other medical treatment, procedure or intervention.
- Advisory Committee on Immunization Practices (ACIP) – The Advisory Committee on Immunization Practices, or ACIP, is a volunteer committee at the CDC that reviews the evidence on vaccines and makes recommendations for who should receive which vaccines and when.
- Alpha-gal syndrome – Alpha-gal syndrome is a red meat allergy caused by the bite of certain ticks. The allergy is known as Alpha-gal…
- Antibiotic resistance/anti-microbial resistance – When an antibiotic or antimicrobial has lost its ability to effectively control or kill a bacteria, fungi, or parasite, it…
- Antibiotic stewardship – Antibiotic stewardship is a public health effort to work with health providers to ensure the judicious use of antibiotics prescribing.…
- Antigen – An antigen is the specific part of a pathogen (or potential or suspected pathogen, in the case of autoimmune disease)…
- Antigenic drift and shift – Before COVID-19, this term was often used when discussing the influenza virus because flu is among the fastest mutating viruses…
- Asymptomatic carrier – A healthy person who is infected by a pathogen and showing no symptoms of disease. People can become infected with…
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- Bacteria – Single-celled microorganisms that don’t require living hosts. They come in many different shapes and thrive in diverse environments including extreme…
- Bacteriophages – Phages are viruses that are the natural enemies of bacteria. The word ‘bacteriophage’ means “bacteria eater.” Phages exist anywhere bacteria…
- Basic reproduction number – A basic reproduction number is a number calculated from mathematical modeling to represent how contagious a particular infectious disease is…
- Basket trial – A basket trial is a type of clinical trial that tests a single investigational drug or a combination of drugs across multiple cancer populations that have a shared genetic mutation, alteration, or biomarker.
- Biosafety labs and standards – Scientists have developed standards for biosafety labs to enable researchers to study contagious pathogens like SARS-CoV-2, the virus that causes…
- Bioterrorism – A form of terrorism involving the deliberate release of biological agents, such as a virus or bacteria, or toxins to…
- Blood borne pathogens – Blood borne pathogens are bacteria, viruses and other microorganisms that live in the bloodstream and can cause disease. They are…
- Botulism – A rare but very dangerous disease caused by a toxin made primarily by the Clostridium botulinum bacteria, though it can be caused by others.
- Breakthrough infection – In vaccinology, a breakthrough infection means a person develops an infection from a pathogen after vaccination and may indicate the…
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- Campylobacter – This bacteria is the most most common cause of diarrheal illness in the U.S., with an estimated 1.5 million cases annually.
- Candidate vaccine viruses – A candidate vaccine virus (CVV) is a virus that has been developed in a lab for the purposes of being…
- Cell-mediated immune response – A cell-mediated immune response refers to several different types of cells that attack the infection without using antibodies.
- Chronic wasting disease – This is a potentially emerging disease for humans, though it has not yet jumped from animals to people. The disease…
- Common cold – Although everyone has heard of — and probably experienced — the common cold, they frequently do not realize that colds…
- Contact tracing – Contact tracing is a monitoring process used to stop the spread of an infectious disease outbreak. The process is a…
- Contagious – The term referring to a disease that is spread by contact between people or animals. Direct contact includes disease spread…
- Containment versus mitigation in infectious diseases – Containment and mitigation tools differ depending upon the kind of infection that is spreading, and the availability of medical treatments…
- Cordyceps fungus – A spore-producing organism (scientifically its full name is Ophiocordyceps unilateralis) that can invade the brains of ants and other insects,…
- Coronavirus – Coronaviruses are a family of viruses, which cause respiratory illness in humans. It gets its name from the crown-like halo…
- Countermeasure Injury Compensation Program (CICP) – The Countermeasure Injury Compensation Program (CICP) provides compensation to people injured by “countermeasures” that were employed by the federal government for various public health emergencies or security threats.
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- Disease elimination vs. eradication – Eradication refers to a disease being completely, literally eradicated from the earth: no cases occur at all, from any source.…
- Disease X – Disease X is a placeholder name for an “unexpected” disease. The World Health Organization declared in 2018 that Disease “X”…
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- E. coli – While this common bacteria is mostly harmless, some strains can cause diarrhea, stomach cramps, vomiting and more.
- Ecologist – A scientist who studies how animals and plants interact with the environment. Disease ecologists study the interactions between pathogens (i.e.,…
- Emerging disease – A term in epidemiology that indicates that a disease has new or increasing occurrences within a geographic area or population.…
- Endemic – In biology, an endemic species is one that is native to specific regions. In epidemiology, endemic refers to the circulation…
- Enteric – The term for a disease of the intestine. It is commonly used in reference to pathogens that have been ingested…
- Enteroviruses – A group of viruses that typically occur in the gastrointestinal tract, but on rare occasions, can spread to the central…
- Epidemic – A group of cases of a specific disease or illness clearly more than what one would normally expect in a…
- Epidemiological triangle – The components that contribute to the spread of a disease. Deeper diveTo understand how an infectious disease spreads, public health…
- Epidemiologist – Scientists who study the causes, patterns, frequency, and locations of diseases, and use the information to prevent future outbreaks. Epidemiologists…
- Etiology – The cause of a disease or condition; most often etiology refers specifically to the biological mechanisms underpinning a particular condition.
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- False balance – A lapse in responsible reporting referring to using outliers’ voices to state opinions that contradict the facts simply to provide…
- Filovirus – Filoviruses are part of a virus family called Filoviridae and are the cause of severe hemorrhagic (internal bleeding) disease in…
- Flattening the Curve – It is a term used to refer to the curve in the projected number of people who will contract a…
- Flavivirus – A kind of virus found primarily in ticks and mosquitos that can occasionally infect humans. Members of this virus family…
- Fungal infection – Fungi are spore producing organisms like yeast, molds, and mushrooms. They are common in the environment and are seen as…
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- Gain-of-function – The term refers to laboratory techniques used to enhance aspects of a pathogen to make it more deadly and transmissible. This is…
- Gram-positive and gram-negative bacteria – Bacteria are classified based on a chemical stain that can be seen through the microscope. Bacteria that turn purple under…
- Guillain–Barré Syndrome – Guillain–Barré syndrome (GBS) is a rare neurological autoimmune disease in which a person’s immune system attacks parts of the peripheral…
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- Hand hygiene – Washing one’s hands is among the most effective ways of reducing the spread of infections. Deeper dive In health care…
- Hand, foot and mouth disease – This is a mild contagious viral infection that usually affects children younger than five. Hand foot and mouth disease is…
- Helminth-caused infections – Helminths are parasitic worms. Worms can be transmitted to humans in fecal material, from insects or from walking barefoot on…
- Herd immunity – A means of protecting a whole community from the spread of an infectious disease. The more people (a herd) that…
- Highly Pathogenic Avian Influenza (HPAI) – Highly Pathogenic Avian Influenza (HPAI) is a category of influenza A viruses that infect birds, causing severe illness and mortality…
- Human metapneumovirus (HMPV) – A virus that can cause upper and lower respiratory illness in people, especially in older adults, children and those with…
- Human papillomavirus (HPV) – HPV refers to a group of more than 200 viruses most often spread through sexual activity or other close contact with the genitals.
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- Immunity – The ability of the body to respond to and resist bacteria, viruses, fungi, and parasites based on its ability to…
- Immunogenicity – Immunogenicity refers to how effectively a foreign substance — usually an antigen — induces an adaptive immune response in the body.
- Immunology – The branch of biology that covers the study of the immune system in all organisms. Immunologists study the physiological function…
- Incidence – Incidence is the rate of newly diagnosed cases of a disease. It is different from prevalence, the total number of cases in a population.
- Incubation period – The incubation period is the time that elapses between exposure to an infectious agent and when symptoms first appear.
- Infection-to-fatality rate (IFR) – An epidemiology term that quantifies the chances that a person who contracts an infection from a pathogen, will die from…
- Infections diseases as cancer cause – Cancer is a set of diseases characterized by abnormal cell growth triggered by a genetic defect. Sometimes an infectious agent…
- Infectious – A disease that can be transmitted to other individuals. An infectious disease is a disease that is caused by the…
- Infectious disease modeling – Despite great strides in medication, sanitation, hygiene and in animal and pest control, infectious diseases remain an enormous threat to…
- Infectious dose – Infectious diseases spread when a healthy person encounters a pathogen expelled by someone sick, such as through a cough, sneeze,…
- Influenza (flu) – Influenza is a respiratory disease caused by the influenza virus, and is endemic to humanity. The virus is always around,…
- Influenza A subtypes – There are four types of influenza: A, B, C, and D, with A and B a focus among virologists and…
- Influenza-like illness (ILI) – This is a catch-all term that refers to influenza and other respiratory illnesses in the CDC’s surveillance systems for respiratory disease.
- Isolation – This policy involves separating people known or suspected to be infected with a contagious disease from those who are not…
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- Listeria – A bacteria that causes the food-borne illness listeriosis, estimated to affect about 1600 people and kill 260 people each year in the U.S.
- Lyme disease – Lyme disease, in the U.S., is caused by the bacteria B. burgdoreri, and is transmitted through the bite of a…
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- Messenger RNA (mRNA) vaccine – An mRNA vaccine refers to an immunization that uses a person’s own cells to create the antigen and develop immunity against a pathogen.
- Microbiome – The microbiome refers to the community of microbes — bacteria, viruses, yeasts, and fungi — that live on and in…
- Middle Eastern Respiratory Syndrome (MERS) – MERS is a coronavirus that emerged in 2012 in Saudi Arabia and subsequently spread to several other countries. It has…
- Mpox – On Nov. 28, the World Health Organization renamed monkeypox disease as ‘mpox’ to remove the ‘racist and stigmatizing’ language that…
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- Neglected tropical diseases – Diseases that could be controlled or even eliminated through mass administration of medication or vaccination but haven’t been because of…
- Neutralizing antibodies – These are a type of antibody, a protein produced by the immune system to fight off pathogens and other foreign substances or substances the immune system perceives as a threat.
- Non-communicable diseases – Non-communicable diseases are usually chronic illnesses that aren’t physically transmissible from person to person and last three months or longer.…
- Nosocomial – This term is usually used in reference to an infection acquired while under medical care, usually at a hospital. A…
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- Oncoviruses – Oncoviruses are viruses that can cause cancer. One of the most common and familiar is human papillomavirus (HPV).
- One Health – One Health is a growing field within public health that embraces the connection between animals, humans and the environment and…
- Opportunistic infection – An infection caused by pathogens — a bacteria, fungi, parasite, or virus — that has taken advantage of a person’s…
- Outbreak – A disease outbreak is the occurrence of cases of a disease more than what would normally be expected in a…
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- Pandemic – The definition is subject to debate among public health officials and scientists, but generally it is an epidemic extending over…
- Passive immunization – Passive immunization is the act of providing antibodies to the immune system that it did not create itself instead of stimulating the immune system to create antibodies.
- Pathogen – Any organism that causes disease. Pathogens include bacteria, virus, and fungi. The body comes in contact constantly with pathogens, but…
- Pertussis – Pertussis is also known as whooping cough. It is a contagious respiratory disease, spread by air droplets in breath, and…
- Presumptive positive – This is a term used by the Centers for Disease Control and Prevention related to the diagnostic testing process for…
- Prevalence – Prevalence is the total of cases of a disease existing in a population. It’s different from incidence, the rate of newly diagnosed cases.
- Prion diseases – Prion diseases, also called transmissible spongiform encephalopathies (TSEs) are a family of rare brain disorders. The disease agent is believed…
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- Quarantine and isolation – These are terms that are often confused by the public. A quarantine involves restricting the moment of a healthy person…
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- R-naught/R0 – The R0, pronounced R-naught, is a number epidemiologists use to determine how contagious a disease is and a community’s susceptibility…
- Ring vaccination – This is a public health strategy aimed at halting the spread of a viral infection. It involves vaccinating all people…
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- Sepsis – Sepsis is an extreme bodily response to an infection.
- Serologic test – A blood test to detect the presence of antibodies against a microorganism.
- Social epidemiology – Social epidemiology is a subset of epidemiology. It is the study of causes, patterns, frequency and locations of diseases to…
- Spillover – A spillover event, infection, pathogen or disease occurs when a zoonotic pathogen infects a new host species like humans.
- Staphylococcus aureus – This bacteria is the source of “staph” infections, which can occur in healthcare settings, result from food poisoning, and even be life-threatening.
- Subclinical infection – Subclinical infections refer to an infection occurring in the body but at low enough levels that no physical symptoms occur.
- Super spreader – Someone who is infected with a particular disease and responsible for transmitting that bacteria or virus to many other people.…
- Surveillance bias – A selection bias that shows more disease in a population because that population has increased testing and screening.
- Symptomatic case-fatality rate (sCFR) – An epidemiology term that quantifies the risk that a person who is infected with a pathogen, and showing signs of…
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- The Belmont Report – The Belmont Report lays out the ethical principles that should guide how medical/biological/behavioral research is carried out in humans.
- Titer – In regards to infectious disease, “titer” nearly always refers to the amount of antibodies a person has against a particular pathogen.
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- Vaccine – Vaccines are agents (usually dead or weakened microorganisms, or a genetic piece of the organism) that elicit a specific immune…
- Vaccine Adverse Event Reporting System (VAERS) – The Vaccine Adverse Event Reporting System (VAERS) is a passive monitoring system that collects reports of adverse events after vaccinations.
- Vaccine efficacy and effectiveness – Efficacy refers to how well a vaccine works in clinical trials whereas effectiveness refers to how well a vaccine works in everyday life.
- Vaccine hesitancy – Vaccine hesitancy is a term that has emerged as a more neutral way to discuss attitudes toward vaccines, without identifying…
- Vaccine Injury Compensation Program (VICP) – The National Vaccine Compensation Program (VICP) provides compensation to people who have experienced significant injuries from vaccines.
- Vaccine platform – A method of manufacturing vaccines for broad use and multiple pathogens.
- Vector-borne diseases – Vectors are organisms that pass diseases from animals to humans or between humans.
- Viral load – A measure of virus particles. Generally, it refers to the amount of virus present in the body once a person…
- Virologist – Virology is the study of viruses and virus-like agents, including their types, disease-producing properties, how they multiply and their genetics.
- Virulence – The degree of damage a pathogen can cause to the body.
- Virus – A biological entity with a protein covering that is neither alive nor dead.
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- Wastewater surveillance – The practice of monitoring sewage in specific cities or other regions for the presence of specific pathogens like SARS-CoV-2.
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- Zoonotic – A zoonotic disease refers to a pathogen that has been living within an animal, and then, for an environmental or…