DD 2022-23

scioly disease detectives terms

Cluster

An aggregation of cases over a particular period closely grouped in time and space, regardless of whether the number is more than the expected number

Endemic Disease

Present at a continuous level throughout a population/geographic area; constant presence of an agent/health condition within a given geographic area/population; refers to the usual prevalence of an agent/condition.

Epidemic

Large numbers of people over a wide geographical area are affected.

Etiology

Study of the cause of a disease.

Fomite

A physical object that serves to transmit an infectious agent from person to person. An example of this is lice on a comb. The comb is the fomite and the lice are the agent that can make your hair itch.

Incubation Period

Time in between when a person comes into contact with a pathogen and when they first show symptoms or signs of disease.

Index Case

First patient in an epidemiological study (also known as patient zero or primary case).

Latent Period

Time in between when a person comes into contact with a pathogen and when they become infected.

Morbidity

Rate of disease in a population.

Mortality

Rate of death in a population.

Outbreak

More cases of a particular disease than expected in a given area or among a specialized group of people over a particular period of time.

Pandemic

An epidemic occurring over several countries or continents and affecting a large proportion of the population.

Plague

A serious, potentially life-threatening infectious disease that is usually transmitted to humans by the bites of rodent fleas. It was one of the scourges of our early history. There are three major forms of the disease: bubonic, septicemic, and pneumonic.

Nosocomial Disease

An infection that is acquired in a hospital.

Risk

The probability that an individual will be affected by, or die from, an illness or injury within a stated time or age span. Risk of illness is generally considered to be the same as the Incidence (see below) and the terms are used interchangeably. Age-span is not usually a consideration in this usage. Risk of death from a particular illness is expressed as the Case Fatality Rate (Number deaths due to a disease/Number with the disease) or the Cause-specific Mortality Rate (Number deaths due to a disease/Number in population). Age span is a more common consideration in this last usage.

Surveillance

The systematic and ongoing collection, analysis, interpretation, and dissemination of health data. The purpose of public health surveillance is to gain knowledge of the patterns of disease, injury, and other health problems in a community so that we can work towards their prevention and control.

Vector

An animal that transmits disease. For example, a mosquito is a vector for malaria.

Zoonosis

An infectious disease that is transmissible from animals to humans.

Symptomatic

Showing symptoms or signs of injury.

Asymptomatic

Showing no signs or symptoms, although can be carrier of disease.

Incubatory Vector

When an individual transmits pathogens immediately following infection but prior to developing symptoms

Chronic Vector

Someone who can transmit a disease for a long period of time

Genetic Vector

has inherited a disease trait but shows no symptoms

Transient/Temporary Vector

Someone who can transmit an infectious disease for a short amount of time

Random error

the result of fluctuations around a true value because of the sample population. As the term implies, it is random, so it is impossible to correct. Reduce by increasing the sample size and making measurements more precise. While these techniques would decrease random error, they can also be expensive.

Precision

a measure of random error that is inversely related, so increasing random error decreases precision.

Systematic error

is any error other than random error. For example, systematic error can occur if the markings on your ruler are wider. This would make the numeric measurements less than what they actually are, making all data collected inaccurate. However, trends observed may still be preserved.

Selection bias

when selection of participants for a study is affected by an unknown variable that is associated with the exposure and outcome being measured.

Information bias

when bias is introduced through an error in measurement or observation

recall bias

when studied, some subjects may more easily recall specific habits related to a disease or condition than subjects not affected with the disease or condition.

Confounding bias

bias resulting from mixing effects of several factors. Unlike selection and information bias, confounding bias deals with causation and not variations in study results.

spectrum of disease

the disease process may result in illness that ranges from mild to severe or fatal

Agent

A microbial organism with the ability to cause disease.

Reservoir

A place where agents can thrive and reproduce.

Portal of Exit

A place of exit providing a way for an agent to leave the reservoir; the route a pathogen takes out of an infected host. Portals of exit tend to be fairly well defined. The three most common portals of exit are the skin, gastrointestinal tract, and respiratory tract.

Mode of Transmission

Method of transfer by which the organism moves or is carried from one place to another; the transfer of disease-causing microrganisms from one environment to another, particularly from an external environment to a susceptible individual. There are three general categories of transmission: contact, vehicle, and vector.

Portal of Entry

An opening allowing the microorganism to enter the host; the route a pathogen takes to enter a host. Many pathogens are not able to cause disease if their usual portal of entry is artificially bypassed. The most common portal of entry is the mucous membrane of the respiratory tract.

Susceptible Host

A person who cannot resist a microorganism invading the body, multiplying, and resulting in infection.

Contact Transmission

sub-categories include direct (person-to-person), indirect (fomite), or droplet.

Direct Contact

occurs through touching, kissing, dancing, etc . To prevent direct contact transmission, wear gloves and masks, etc.

Indirect Contact

occurs from a reservoir via inanimate objects called fomites. Fomites are basically almost anything an infected individual or reservoir can touch, upon which can be left a residue of contagious pathogen. Exceptions include the various inanimates referred to as vehicles: food, air, and liquids.

Droplet Transmission

consequence of being coughed, sneezed, or spit on. To be considered droplet transmission, mucous droplets must still be traveling with the velocity imparted on it leaving the mouth. As a rule of thumb, this is up to one meter after exiting the mouth. Any further and this is considered airborne transmission.

Vehicle Transmission

transmission via a medium such as food, air, and liquid, which are all routinely taken into the body, and thus serve as vehicles into the body.

Airborne Transmission

occurs via droplets (typically mucous droplets) where droplets are liquids that remain airborne whether as aerosols (very small droplets) or associated with dust particles.

Food borne Transmission

any number of pathogens are found in food and not killed during processing may be transmitted via food product. Salmonella especially tends to be part of the normal flora of chickens and consequently associated with chicken products.

Water borne Transmission

fecal contaminated water. Generally, this is via sewage contaminated water supplies. It is especially gastrointestinal pathogens that are present in feces and therefore which rely on this type of transmission.

Vector Transmission

no entry

Portals of Entry to the Nervous System

the brain is typically fairly resistant to bacterial infection. There are four common portals of entry to the nervous system. For an organism to take advantage of these routes, they must display increasingly specialized adaptations as read from first to last: parenteral, via the blood, via the lymphatic systems, and up the peripheral nerve axons.

Primary prevention

early intervention to avoid initial exposure to agent of disease preventing the process from starting

Secondary prevention

during the latent stage (when the disease has just begun), process of screening and instituting treatment may prevent progression to symptomatic disease

Tertiary prevention

during the symptomatic stage (when the patient shows symptoms), intervention may arrest, slow, or reverse the progression of disease

Quaternary prevention

set of health activities to mitigate or avoid consequences of unnecessary/excessive intervention of the health system. Social credit that legitimizes medical intervention may be damaged if doctors don't prevent unnecessary medical activity and its consequences.

Active Immunity

occurs when the person is exposed to a live pathogen, develops the disease, and becomes immune as a result of the primary immune response

Passive Immunity

short-term immunization by the injection of antibodies, such as gamma globulin, that are not produced by the recipient's cells. Naturally acquired passive immunity occurs during pregnancy, in which certain antibodies are passed from the maternal into the fetal bloodstream.

Herd Immunity

protecting a whole community from disease by immunizing a critical mass of its populace. Vaccination protects more than just the vaccinated person. By breaking the chain of an infection's transmission, vaccination can also protect people who haven't been immunized. But to work, this protection requires that a certain percentage of people in a community be vaccinated.

Z-Test

Used to compare two means when the population variances are known and the sample size is greater than 30

T-Test

Used to compare two means when sample size is greater than 30

Paired T Test

Used to compare multiple sets of data

Fischer's Exact Test

Fischer's test searches for non-random associations between two categorical variables.

McNemar's Test

The McNemar Test is similar to a Chi-Square, except that it uses matched paired data.

Maentel Haenszel Test

The Cochran-Maentel-Haenszel Test aims to find the association between variables while controlling for confounding.

ANOVA

The analysis of variance test, or ANOVA, is a statistical measure used to compare two or more means.

Convalescent Vector

Humans are also capable of spreading disease following a period of illness, typically thinking themselves cured of the disease.