Term
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Definition
| The study of patterns of health and disease in POPULATIONS and the factors that influence these patterns. |
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Term
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Definition
| Describing the patterns of disease in relation to individuals, place, and time. A logical approach to solving disease problems regarding cause, predisposing factors and intervention. A systematic approach for the critical evaluation of scientific literature. |
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Term
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Definition
| Describes patterns and formulates hypotheses. Answers who, what, when, where. |
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Term
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Definition
| Involves analysis of data to test hypotheses. Answers why and how. |
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Term
| Experimental Epidemiology |
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Definition
| Involves population experiments to test hypotheses. Ex: Vaccine and drug trials |
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Term
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Definition
| Uses mathematical models to study disease. |
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Term
| Epidemiological Sub-Disciplines |
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Definition
| Clinical, Computational, Genetic, Field (Shoe-leather), Participatory, Molecular, Spatial |
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Term
| What three forms of veterinary medicine are complementary to each other? |
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Definition
| Clinical medicine, pathology, and epidemiology |
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Term
| What is a determinant of health? |
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Definition
| Any factor that when altered produces a change in the frequency or characteristics of disease. Can be physical, biological, or behavioral. |
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Term
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Definition
| Have a major effect in inducing disease. Ex: rabies virus |
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Term
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Definition
| Are predisposing or enabling factors to disease. Ex: poor hygiene. |
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Term
| Intrinsic (Endogenous) Determinants |
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Definition
| Are internal to the host. Ex: breed, species, sex. |
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Term
| Extrinsic (Exogenous) Determinants |
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Definition
| Are external to the host. Ex: poisons, trauma, radiation. |
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Term
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Definition
| Agent, Environment, Host. |
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Term
| Agent Factor Determinants |
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Definition
| Host range, infectivity, infectious dose, viability, pathogenicity, virulence, immunogenicity, and antigenic stability. |
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Term
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Definition
| Ability to enter, multiply, and produce change in a host. Variable from agent to agent. Infection, contamination, and pollution are taken into consideration. |
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Term
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Definition
| Ability to withstand environmental stress. |
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Term
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Definition
| Genotype, age, sex, species/breed, immunological status, occupation, size and conformation, social and ethological, coat color. |
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Term
| Environmental Determinants |
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Definition
| Location/geography, climate (micro/macro), husbandry (housing/nutrition/management) |
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Term
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Definition
| Association of a factor and disease does NOT necessarily imply cause-effect relationship. Ex: carrying matches associated with lung cancer. |
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Term
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Definition
| Determinants interact. Ex: interaction between the host (gene) and environment (stressors). |
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Term
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Definition
| Consists of direct and indirect causes of disease. A method of conceptualizing how multiple factors combine to cause disease. Causes are interconnected through a series of chains or web structures. |
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Term
| Transmission of Infection |
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Definition
| Depends on its successful transmission to a susceptible host and its multiplication to maintain the life-cycle. |
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Term
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Definition
| Any living organism or inanimate matter where an infectious agent normally live and multiplies, maintains and perpetuates itself, and from which it can be transmitted. |
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Term
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Definition
| If the reservoir is an animal. |
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Term
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Definition
| Center where infection settles and from where it spreads. |
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Term
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Definition
| An animal or substance from which an infectious agent passes directly to a susceptible host. May or may not be a reservoir. |
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Term
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Definition
| An infected person or animal that sheds pathogenic/potentially pathogenic organisms in the absence of discernible clinical disease and serves as a potential source of infection. |
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Term
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Definition
| Healthy (asymptomatic), incubatory, convalescent, intermittent shedders, and chronic carriers. |
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Term
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Definition
| Shed agent prior to appearance of clinical signs. |
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Term
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Definition
| Shed agent for short periods after signs have abated. |
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Term
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Definition
| Shed agent for a moderate period of time after recovery from disease. |
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Term
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Definition
| Place of entry/exit of agents from the reservoir. Ex: nose, mouth, urine, seme, tears, body surface, or multiple sites. |
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Term
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Definition
| Secretions, excretions, or other body fluids or tissues |
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Term
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Definition
| Inanimate object contaminated with the primary vehicle. |
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Term
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Definition
| Usually invertebrates that transmit infectious agents. |
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Term
| Ways of Possible Direct Transmission |
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Definition
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Term
| Ways of Possible Indirect Transmission |
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Definition
| Vehicle and fomites, airborne, ingestion (foodborne/waterborne), vectors. |
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Term
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Definition
| Mechanical and biological |
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Term
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Definition
| Vector in which the infectious agent neither multiplies nor develops. Transmission interval is short. May be external or internal carriers of agent. |
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Term
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Definition
| Vector in which infectious agent undergoes some change (multiplication, maturation, sexual reproduction). Requires an extrinsic incubation period before transmission can occur. |
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Term
| Extrinsic Incubation Period |
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Definition
| Time required for development of an agent in a vector from the time of infection of the vector to the time when the vector is infective. |
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Term
| Types of Biological Transmission |
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Definition
| Developmental, propagative, cyclopropagative. |
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Term
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Definition
| The time from exposure to the chemical to resultant disease. |
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Term
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Definition
| Interval between effective exposure to an agent and the onset of the related disease. |
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Term
| Developmental Transmission |
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Definition
| An essential development phase of agent occurs in vector. |
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Term
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Definition
| Multiplication of the agent occurs in the vector. |
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Term
| Cyclopropagative Transmission |
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Definition
| Both development and multiplication occur in the vector. |
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Term
| Transstadial Transmission |
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Definition
| Agent survives through various stages of vector development. |
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Term
| Indirect Transmission Types |
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Definition
| Transovarian, transstadial, flying vectors, non-flying vectors, water-inhabiting vectors, and latrogenic. |
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Term
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Definition
| Created by a doctor during surgical and medical practice. |
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Term
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Definition
| Ease and speed with which an agent is transmitted in a population of susceptibles. |
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Term
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Definition
| Is associated with incubation period. |
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Term
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Definition
| Is a plant, animal, or arthropod that is capable of being infected by an infectious agent. Replication and development of the agent usually occurs here. |
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Term
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Definition
| Susceptible, definitive, intermediate, incidental (dead-end/accidental), primary (natural), secondary (aberrant), paratenic, reservoir, link, amplifier. |
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Term
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Definition
| One in which an organism undergoes its sexual phase of reproduction. |
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Term
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Definition
| One in which an agent undergoes some development, usually asexual reproduction. |
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Term
| Incidental (dead-end/accidental) Host |
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Definition
| Does not usually transmit agent to other hosts. |
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Term
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Definition
| One that maintains an infection in an endemic area. Agents depend on this host for long-term existence. Also called a maintenance host. |
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Term
| Secondary (aberrant) Host |
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Definition
| One that is involved in the life-cycle of an agent, particularly outside the endemic area of the agent. Can sometimes act as a maintenance host. |
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Term
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Definition
| One in which an agent is transmitted mechanically. No development of the agent occurs in this host. |
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Term
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Definition
| One that links other host species. |
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Term
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Definition
| One in which there is a sudden increase in the amount of agent due to an increase in host population. |
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Term
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Definition
| One in which an agent usually lives and multiplies. Frequently primary host. |
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Term
True or False?
Mechanical vectors can be reservoirs. |
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Definition
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Term
True or false?
Cyclopropagative transmission is one in which both the development and multiplication occur in a vector. |
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Definition
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Term
| Extrinsic incubation period is |
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Definition
| used to refer to time before an agent can be transmitted in biological vectors |
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Term
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Definition
| ability of host to resist disease/infection |
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Term
| Host immunity maybe be _________ or ________. |
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Definition
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Term
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Definition
| geared towards an antigen |
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Term
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Definition
| physiological barriers of defense |
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Term
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Definition
| usually genetic form of immunity |
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Term
| Acquired immunity include _____ and ______ immunity |
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Definition
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Term
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Definition
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Term
| Active immunity is formed by |
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Definition
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Term
| Passive immunity is developed by |
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Definition
| maternal antibodies or serum transfer |
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Term
| Host immunity depends on three things: |
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Definition
| nature of agent, challenge dose, environmental factors |
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Term
| Host immunity is _______ not _______. |
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Definition
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Term
| Example of nature of agent |
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Definition
| virulence or antigen variability |
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Term
| Example of challenge dose: |
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Definition
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Term
| Example of environmental factors: |
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Definition
| outside stressors - hygiene or management |
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Term
| For long term survival, infectious agents require hosts with _________ immunity |
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Definition
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Term
| It is never in the interest of the infectious agent to ______ the host. |
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Definition
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Term
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Definition
| looking at immunity within a herd |
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Term
| Herd immunity depends on the percent of __________. |
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Definition
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Term
| The _______ the proportion of immune individuals in a population, the higher the level of herd immunity. |
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Definition
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Term
| The lower the proportion of immune individuals in a population, the ______ the level of herd immunity. |
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Definition
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Term
| Rate of infectious disease spread in a population depends on (5) things: |
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Definition
| characteristics of the infectious agent, host immunity of the animals in the population, population structure, population dynamics, contact rate |
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Term
| Examples of population structure: |
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Definition
| proportion or immune and susceptible animals; presence of alternative hosts and vectors |
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Term
| Example of population dynamics: |
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Definition
| movement, social distance, behavior, etc. |
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Term
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Definition
| rate at which suceptibles interact with infected animals |
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Term
| Ideally you want a ________ contact rate. |
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Definition
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Term
| Example of reducing contact rate: |
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Definition
| isolate infected/unknown animals |
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Term
| An animal that is shedding an infectious agent primarily after recovering from clinical disease can be classified as a |
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Definition
| chronic or convalescent carrier |
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Term
| An animal that intermittently sheds an infectious agent for moderate periods of time after recovery from disease is an |
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Definition
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Term
True or false?
A reservoir can be a source of infection but a source of infectious is not necessarily a reservoir. |
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Definition
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Term
| What is not an example of direct transmission? |
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Definition
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Term
| An infection that results in no perceptible clinical signs is |
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Definition
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Term
| Expiratory droplets as a mode of transmission, have little impact in natural ecosystems because |
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Definition
| droplets are heavy which requires that animals be in close proximity |
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Term
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Definition
| created by a doctor during surgical and medical practice |
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Term
| T/F - Is it possible to control diseases by changing herd immunity through alterations of herd structure without inducing individual host immunity? |
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Definition
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Term
| host immunity is NOT influenced by population structure becasue that is herd immunity not _______ immunity |
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Definition
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Term
| T/F Disease determinants do not occur randomly in the population |
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Definition
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Term
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Definition
| the usual frequency of occurrence of a disease in a population; the constant presence of the disease in the population |
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Term
| endemic occurance can be used to describe both |
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Definition
| clinical and sub-clinical disease |
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Term
| 3 types of endemic occurance |
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Definition
| hyperendemic, hypodendemic, and holoendemic |
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Term
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Definition
| disease is continuously present at high level, affecting all age groups equally (eg: rabies in Canadian fox pop) |
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Term
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Definition
| disease is continuously present at low level, affecting all age groups(eg:TB in humans and cattle) |
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Term
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Definition
| high level of infection begins early and affects most of the young population resulting in state of equilibrium so that the adult population show evidence of disease much less commonly (eg: GI parasites, malaria) |
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Term
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Definition
| disease at level in excess of the expected or endemic level |
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Term
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Definition
| population is exposed to one or more factors that were not present previously |
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Term
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Definition
| epidemic occurring world wide, over an area, crossing international boundaries, and usually affecting a large number of individuals (AIDS) |
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Term
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Definition
| when disease occurs irregularly and haphazardly, usually the result of small localized outbreaks |
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Term
| 3 factors affecting the shape of an epidemic curve |
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Definition
| incubation period of disease, infectivity of the agent, and proportion of susceptible hosts in the population |
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Term
| 7 key points in constructing an epidemic curve |
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Definition
| look at them in the notes, I'm not writing all that here. (7 key points) |
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Term
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Definition
| many animals exposed to a common source --> causes rapid progression and regression, compressed in time, and approaches symmetry at average incubation period |
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Term
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Definition
| initial (primary) cases infect susceptible individuals that become secondary cases - gradual progression, tendency to plateau, feature of vector and animal to animal spread |
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Term
| When looking at a propagating epidemic curve, a ______ peak may occur as a result of movement/introduction of animals. |
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Definition
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Term
| Time interval between primary and secondary cases is the |
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Definition
| incubation period of infection |
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Term
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Definition
| short-term, exhibited in epidemics, result of periods of fluctuations in disease occurrence - seasonal trends or secular trends |
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Term
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Definition
| long term (sev. years) increase or decreases in disease rates related to temporal patterns |
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Term
| Occurrence in a population of a group of illnesses of similar nature in excess of normal expectancy |
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Definition
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Term
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Definition
| systematic procedure to identify causes and sources of epidemics - requires fast action and correct solution to the problem |
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Term
| When identifying and describing an outbreak make sure to include 3 things |
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Definition
| time (temporal patterns), place (spatial patterns), and individual (animal patterns) |
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Term
| How many steps are there to an outbreak investigation? BTW he said know all of these.... |
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Definition
| 10 - and ya better learn 'em. |
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Term
| Incubation period of giardiasis is 2-12 days, but typically averages 6 days. What interval would you use when constructing an epidemic curve? |
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Definition
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Term
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Definition
| Primary (involve), Secondary, and Tertiary |
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Term
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Definition
| to reduce the incidence of disease |
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Term
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Definition
| reduce prevalence of disease by shortening duration |
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Term
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Definition
| reduce the number and or impact of complications (because other 2 types failed)eg:chemotherapy |
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Term
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Definition
| to reduce disease prevalence to a level that is no longer a major health and or economic problem; contain disease by limiting or stopping its spread |
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Term
| Name the methods of disease control |
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Definition
| slaughter, quarantine, reduction of contact, chemical use, modification of host resistance, environmental and/or MGMT control, education, biological control |
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Term
| 2 types of vaccine approaches |
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Definition
| natural vaccination - ring vaccine, form ring around area where outbreak is; strategic vaccination - barrier vaccine, vax area where infected animals will pass |
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Term
| When referring to disease elimination say ________ _________ not total eradication or partial eradication |
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Definition
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Term
| random spatial occurrence |
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Definition
| exhibited by sporadic outbreaks |
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Term
| clustering spatial pattern |
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Definition
| aggregation of disease or other events in amounts greater than would be expected by chance alone |
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Term
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Definition
| interaction between the place and time of occurrence of a disease |
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Term
| common types of maps used |
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Definition
| point maps, proportional circle maps, ad choropleth maps |
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Term
| 8 methods of disease control |
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Definition
| slaughter, quarantine, reduce contact rate, chemical use, environmental/management control, education, biological control, modification of host resistance |
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Term
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Definition
| the extent to which the results of the study apply to my patient |
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Term
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Definition
| the extent to which the content and design of the study eliminate the possibility of error |
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Term
| Best source of information |
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Definition
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Term
| what is wrong with using text books? |
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Definition
| usually out-dated not long after publication |
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Term
| what is wrong with using lecture notes several years after being out of vet school? |
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Definition
| in 5-10 years material taught in curriculum tends to change, notes may be out-dated |
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Term
| what is wrong with expert opinion? |
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Definition
| selective use of evidence - opinionated; medical dogma - beliefs on little supported evidence |
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Term
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Definition
| critically appraised topics |
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Term
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Definition
| measures new cases of disease that develop over a period of time |
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Term
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Definition
| measures existing cases of a disease at a given time |
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Term
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Definition
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Term
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Definition
| P(disease)/1-P(disease) with P being probability of disease |
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Term
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Definition
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Term
| incidence as a proportion |
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Definition
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Term
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Definition
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Term
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Definition
| # new cases of disease in population during a specific period of time / # individuals at risk of developing the disease during the time period |
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Term
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Definition
p=c/n
p = (# observed cases at time t)/(population size at time t) |
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Term
| Causation in relation to what we're studying |
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Definition
| cause and effect relationships in medicine |
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Term
| Causation in relation to what we're studying |
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Definition
| cause and effect relationships in medicine |
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Term
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Definition
| factor that has an association with disease; factor that changes the risk *probability* of developing a disease in the future |
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Term
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Definition
| statsitical relationship between two or more events, characteristics or other variables |
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Term
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Definition
| change in one variable is responsible, directly or indirectly, for an observed change in another variable |
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Term
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Definition
| presence of a risk factor increases the pre-test probability of disease |
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Term
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Definition
| removal of risk factors that are a cause of disease prevents disease |
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Term
| Do epidemiologic studies prove causation |
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Definition
| NO - cannot prove that casation occurs but they may be useful in supporting a causal association |
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Term
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Definition
| there is always the possibility that an observed association is due to chance alone |
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Term
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Definition
| the association results from errors in the study, design, implementation, or analysis |
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Term
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Definition
| relationship is distorted by an add'l variables (confounder) which is associated to the factor under study and the disease |
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