Disease Detectives Flashcards
Epidemiology
The study of distribution and determinants of health-related states in specified populations, and the application of this to control health problems. There are four basic reasons for why disease detectives study and research outbreaks and epidemics. These reasons are: Control and Prevention, Research Opportunities, Training, and Legal Concerns.
Two Basic Types of Epidemiology:
Classical Epidemiology
Population oriented, studies community origins of health problems related to nutrition, environment, human behavior, and the psychological, social, and spiritual state of a population. The event is more aimed towards this type of epidemiology.
Note: There are all sorts of classification systems for epi and the above certainly are examples. One could add research epi vs applied epi to the above list. However probably the most fundamental and common system is Descriptive epi (e.g. person, place and time) vs Analytic epi (hypothesis testing - study design).
Clinical Epidemiology
Studies patients in health care settings in order to improve the diagnosis and treatment of various diseases and the prognosis for patients already affected by a disease. These can be further divided into:
Infectious Disease Epidemiology - heavily dependent on laboratory support
Chronic Disease Epidemiology - dependent on complex sampling and statistical methods
Note: There are all sorts of classification systems for epi and the above certainly are examples. One could add research epi vs applied epi to the above list. However probably the most fundamental and common system is Descriptive epi (e.g. person, place and time) vs Analytic epi (hypothesis testing - study design).
Epidemiology 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
Epidemiology Terms:
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.
Epidemiology Terms:
Epidemic
Large numbers of people over a wide geographical area are affected.
Epidemiology Terms:
Etiology
Study of the cause of a disease.
Epidemiology Terms:
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.
Epidemiology Terms:
Latrogenic
An illness that is caused by a medication or physician.
Epidemiology Terms:
Incubation Period
Time in between when a person comes into contact with a pathogen and when they first show symptoms or signs of disease.
Epidemiology Terms:
Index Case
First patient in an epidemiological study (also known as patient zero or primary case).
Epidemiology Terms:
Morbidity
Rate of disease in a population.
Epidemiology Terms:
Mortality
Rate of death in a population.
Epidemiology Terms:
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.
Epidemiology Terms:
Pandemic
An epidemic occurring over several countries or continents and affecting a large proportion of the population.
Epidemiology Terms:
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.
Epidemiology Terms:
Nosocomial Disease
An infection that is acquired in a hospital.
Epidemiology Terms:
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.
Epidemiology Terms:
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.
Epidemiology Terms:
Vector
An animal that transmits disease but is not the cause of the disease itself. For example, a mosquito is a vector for malaria.
Epidemiology Terms:
Zoonosis
An infectious disease that is transmissible from animals to humans.
Epidemiology Terms:
Symptomatic
Showing symptoms or signs of injury.
Epidemiology Terms:
Asymptomatic
Showing no signs or symptoms, although can be carrier of disease.
Epidemiology Terms:
Incidence (of an illness)
The number of new instances of disease in a population over a given time period. It is expressed as “X cases/Y population/ Z time”.
Epidemiology Terms:
Prevalence (of an illness)
The number of affected persons in the population at any given point in time. It is expressed as “X cases/Y population”.
Note: There are two major ways in which prevalence is measured: period prevalence and point prevalence. Think of point prevalence as a snapshot of the population and its rate of a certain disease at a point in time while period prevalence tracks the prevalence over a certain duration. Note the only difference is that incidence (I) includes time while prevalence (P) does not. Time (D) reflects the duration of the illness or condition. If two conditions have the same incidence in a population, the one with the longer duration will have the greater prevalence. Importantly, P = I*D, so with two of the variables, it is possible to solve for the third.
Epidemiology Terms: Types of Carriers/Vectors:
Convalescent
Humans are also capable of spreading disease following a period of illness, typically thinking themselves cured of the disease
Epidemiology Terms: Types of Carriers/Vectors:
Incubatory
When an individual transmits pathogens immediately following infection but prior to developing symptoms
Epidemiology Terms: Types of Carriers/Vectors:
Chronic
Someone who can transmit a disease for a long period of time
Epidemiology Terms: Types of Carriers/Vectors:
Genetic
Has inherited a disease trait but shows no symptoms
Epidemiology Terms: Types of Carriers/Vectors:
Transient/Temporary
Someone who can transmit an infectious disease for a short amount of time
Epidemiology Terms: Types of Disease Prevention:
Primordial Prevention
Intervention at the very beginning to avoid the development of risk factors the population may be exposed to. Often deals with changing physical and social environments.
Note: In Disease Detectives scenarios, event supervisors will often ask you to brainstorm disease prevention methods. Even if you know very little about the disease, you can brainstorm ideas from the chain of infection for the disease. For example, if the chain of infection describes that a disease is comes in contact with humans through sand at the beach and enters the body through any openings (mouth, nose, etc.), a prevention method could be putting up signs at beaches reminding the public to wash their hands before consuming any food.
Epidemiology Terms: Types of Disease Prevention:
Primary Prevention
Early intervention to avoid initial exposure to agent of disease preventing the process from starting.
Note: In Disease Detectives scenarios, event supervisors will often ask you to brainstorm disease prevention methods. Even if you know very little about the disease, you can brainstorm ideas from the chain of infection for the disease. For example, if the chain of infection describes that a disease is comes in contact with humans through sand at the beach and enters the body through any openings (mouth, nose, etc.), a prevention method could be putting up signs at beaches reminding the public to wash their hands before consuming any food.
Epidemiology Terms: Types of Disease Prevention:
Secondary Prevention
During the latent stage (when the disease has just begun), process of screening and instituting treatment may prevent progression to symptomatic disease.
Note: In Disease Detectives scenarios, event supervisors will often ask you to brainstorm disease prevention methods. Even if you know very little about the disease, you can brainstorm ideas from the chain of infection for the disease. For example, if the chain of infection describes that a disease is comes in contact with humans through sand at the beach and enters the body through any openings (mouth, nose, etc.), a prevention method could be putting up signs at beaches reminding the public to wash their hands before consuming any food.
Epidemiology Terms: Types of Disease Prevention:
Tertiary Prevention
During the symptomatic stage (when the patient shows symptoms), intervention may arrest, slow, or reverse the progression of disease.
Note: In Disease Detectives scenarios, event supervisors will often ask you to brainstorm disease prevention methods. Even if you know very little about the disease, you can brainstorm ideas from the chain of infection for the disease. For example, if the chain of infection describes that a disease is comes in contact with humans through sand at the beach and enters the body through any openings (mouth, nose, etc.), a prevention method could be putting up signs at beaches reminding the public to wash their hands before consuming any food.
Epidemiology Terms: Types of Disease Prevention:
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.
Note: In Disease Detectives scenarios, event supervisors will often ask you to brainstorm disease prevention methods. Even if you know very little about the disease, you can brainstorm ideas from the chain of infection for the disease. For example, if the chain of infection describes that a disease is comes in contact with humans through sand at the beach and enters the body through any openings (mouth, nose, etc.), a prevention method could be putting up signs at beaches reminding the public to wash their hands before consuming any food.
Epidemiology Terms: Immunity:
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.
Epidemiology Terms: Immunity:
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.
Epidemiology Terms: Immunity:
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.
Epidemiology Terms: Chain of Infection:
Agent
A microbial organism with the ability to cause disease.
Epidemiology Terms: Chain of Infection:
Reservoir
A place where agents can thrive and reproduce.
Epidemiology Terms: Chain of Infection:
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. What serve as portals of exit are often not terribly surprising, at least, once something is known of how and where a pathogen replicates and enters new hosts. Respiratory infections tend to utilize the mouth and nose as portals of exit. Gastrointestinal diseases tend to exit in feces or saliva, depending on the site of replication. Sexually transmitted diseases tend to have portals of exit at the urethra or genital region. Blood-borne diseases tend to exit via arthropods, needles, bleeding, or hyperdermic syringes. A more general portal of exit occurs when an infected animal is butchered or an infected person undergoes surgery. The three most common portals of exit are the skin, gastrointestinal tract, and respiratory tract.
Epidemiology Terms: Chain of Infection:
Mode of Transmission
Method of transfer by which the organism moves or is carried from one place to another; the transfer of disease-causing microorganisms 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.
Epidemiology Terms: Chain of Infection:
Portal of Entry
An opening allowing the microorganism to enter the host; the route a pathogen takes to enter a host. Just as with the portals of exit, many pathogens have preferred portals of entry. 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.
Epidemiology Terms: Chain of Infection:
Susceptible Host
A being who cannot resist a microorganism invading the body, multiplying, and resulting in infection.
