Epidemiological terms

Infection

The effective invasion, establishment, development, and/or multiplication of an infectious agent in the tissue of the host constitutes an infection (man or animal). It also suggests that the body reacts in some way, maybe through an immunological reaction or a disease, to defend itself against the intruder. Illness is not usually brought on by an infection. For instance, cutaneous infection

Epidemic

Demos is short for "people," while Epi is Latin for "upon." An epidemic illness is one that affects a lot of individuals in one location and spreads swiftly from a single cause. For instance, the "unusual" occurrence of a disease, a particular health-related behavior, like smoking, or other health-related events, like traffic accidents, clearly exceeds the "expected occurrence" in a community or region. For instance, hundreds of cases of diarrhea would need to occur before it could be deemed an epidemic. Diarrhea outbreak in Jajarkot is an example of an epidemic.

Endemic

En= In; demos= people. It refers to constant presence of a disease or infectious agent within a given geographical area or population group, without importation from outside may also refer to 'usual' or expected frequency of the disease within such area or population group. Certain diseases with continuously appear to a greater or lesser extent in specific regions are called endemic diseases for those areas. eg. malaria, tuberculosis, in Terai, common cold is endemic because somebody always has one etc. Endemic disease can be come epidemic if not controlled or when conditions are favorable.

Sporadic

The word sporadic means scattered about. The cases occur irregularly, haphazardly from time to time and generally infrequently.

Communicable Disease

An illness due to a specific infectious agent, or its toxic products capable of being directly or indirectly transmitted from an infected man or animal or a reservoir to susceptible host is called communicable disease. For example, man, animal or through an intermediate host, vector or the inorganic environment (air, dust, soil, water, food, etc) to man or animal. e.g. tuberculosis, dysentery cholera etc.

Non Communicable Disease

It means the disease which is not transmitted from one person to another, an animal to a person. e.g. heart disease, diabetic etc is known as non communicable disease.

Incubation Period

This is the time interval between the entry of the disease agent into the body and manifestation of the first symptoms of the disease is known as incubation period. During the incubation period, the infectious agent undergoes multiplication in the host. When a sufficient density of the disease agent is built up in the host, the health equilibrium is disturbed and the disease becomes evident.

Isolation

Isolation means the separation of infected person or animal from others for a period of communicability to prevent or limit direct or indirect transmission of the infectious agent is called isolation. This helps to control the spread of epidemic disease. Isolation technique doesn't destroy the pathogenic organisms but it minimizes the chance of being infectious from the infected and that is patient. In isolation, the patient is kept away separately and all the things used by him/her are disinfected, all the medical personnel take universal precaution while giving care and carrying out treatment.

Carrier

An infected person or an animal that harbors a specific disease-causing agent, in the absence of clinical manifestation and serves as potential sources of infection to others is a carrier. As a rule, carriers are less infectious than cases, but epidemiologically, they are more dangerous than cases because they escape recognition, and continuing as they do to live a normal life among the population or community, they readily infect the susceptible individuals over a wider area and longer period, under favorable conditions. For eg. in Hemophilia, female becomes carrier and male sufferer.

Fomites

Fomites are inorganic articles or substances other than water or food contaminated by the infectious discharges from a patient and capable of harbouring and transferring the infectious agent to a healthy person. Fomites include solid clothes, towels linen, handkerchief, caps spoon, pencil, books toys, and drinking glasses, door handles, taps, syringes, instruments and surgical dressing. The fomites play in important role in indirect infection. Diseases transmitted by fomites

Virulence

It is the measure of the severity of disease. In other words, 'disease producing ability of microorganism is called virulence.

Disinfection

Disinfection is the process of eradicating infectious organisms from outside the body by direct contact with physical or chemical means. It may be used to describe both the function of antiseptics and disinfectants. Disinfectants are the substance that eliminates dangerous bacteria (not typically spores) in order to stop the spread of illness. Only inorganic items can benefit from the use of disinfectants. Disinfection eliminates pathogenic organisms from surfaces, excrement, equipment, and work areas. Hydrogen peroxide, potassium permanganate, 70% alcohol, and other substances are typical disinfectants. They are strong enough to eradicate these creatures.

Sterilization

It is a process of destroying all micro-organism and its spores, so that articles widely used in surgical purpose. This process kills all the pathogenic and non-pathogenic organisms including their spores and HIV virus. Sterilization is done by four methods; moist heats, ionizing radiations, dry heat, chemical solutions, & gas. It is usually applied to complete removal of all vegetative and non-vegetative form of micro-organisms.

Contamination

The presence of an infectious agent on a body surface; also on or in clothes, bedding, toys, surgical instruments or dressing or other inorganic articles or substance including water, food & milk is contaminate. Contamination on a body surface does not imply a carrier state.

Zoonosis

An infection or infectious disease transmitted from vertebrate animals to man under natural conditions is zoonosis e.g. rabies, plague, bovine TB. Abattoir (slaughterhouse) and farm workers are at risk of zoonosis.

Nosocomial infection

Nosocomial (hospital acquired) infection is an infection originating in a patient while in a hospital or other health care facility. It denotes a new disorder (unrelated to the patient's primary condition) associated with being in a hospital. It was not present or incubating at the time of admission but appearing after discharge due to acquired from hospital e.g. surgical wounds hepatitis B and urinary tract infection (UTI).

Eradication

Eradication is the reduction of an infectious disease's prevalence in the global host population to zero. It is sometimes confused with elimination, which describes either the reduction of an infectious disease's prevalence in a regional population to zero, or the reduction of the global prevalence to a negligible amount. 

Infestation

For persons or animals, the lodgment development and reproduction of arthropods on the surface of the body or in the clothing e.g. lice,itch mite, worms, etc. Some authorities use the term also to describe invasion of the gut by parasitic worms.

Infectious Disease

Infectious diseases are caused by pathogenic microorganisms, such as bacteria, viruses, parasites or fungi; the diseases can be spread, directly or indirectly, from one person to another. Zoonotic diseases are infectious diseases of animals that can cause disease when transmitted to humans.

Contagious Disease

A contagious disease is a subset category of infectious diseases (or communicable diseases), which are easily transmitted by physical contact (hence the name-origin) with the person suffering the disease, or by their secretions or objects touched by them.

Pandemic

A disease is said to be pandemic when it spreads from one country to not another in a short time or occurs at the same time in different countries. For eg. COVID-19, influenza, cholera, HIV/AIDS, bird flu. swine flu & SARS is also considered as pandemic. 

Exotic

There are certain characteristics that define diseases in animal populations. Sporadic illnesses are those epidemics that only sometimes affect individuals within an animal population, thus the name. Endemic, or enzootic, diseases are those that are typically present in a region and typically represent a stable relationship between the causative agent and the affected animals.

Epizootic

An epizootic (from Greek epi- upon + zoon animal) is a disease that appears as new cases in a given animal population, during a given period, at a rate that substantially exceeds what is "expected" based on recent experience (i.e. a sharp elevation in the incidence rate). Epidemic is the similar term applied to human populations.

Enzootic

It denotes broadly "belonging to" or "resident to", "typical of", or "prevalent in" a specific geography, race, field, region, or habitat; native to an area or scope." Enzootic is the non-human analogue of endemic. The influenza virus seen in some bird populations would be an illustration of an enzootic sickness.

Opportunistic infection

This is infection by an organism (s) that takes the opportunity provided by a defect in host defense to infect the host and hence cause disease. The organism includes herpes simplex, cytomegalovirus, Toxoplasmosis, Mycobacterium tuberculosis, etc. opportunistic infections are very common in AIDS. Infection by an organism that is not normally pathogenic but it can cause disease if resistance is lowered.

Surveillance

The term "continuous study of the variables that affect the occurrence and spread of illness and other aspects of poor health" is used to describe surveillance. Effective control and prevention depend on surveillance, which involves gathering, analyzing, interpreting, and disseminating pertinent data.

Pollution

Pollution is the introduction of contaminants into the natural environment that causes adverse change. Pollution can take the form of chemical substances or energy, such as noise, heat or light. Pollutants, the components of pollution, can be either foreign substances/energies or naturally Occurring contaminants. Pollution is often classed as point source or nonpoint source pollution.