Definitions Flashcards
Epidemiology?
Epidemiology refers to the distribution and determinants of health- related states or events in specifies populations and the application of this study to the control of health problems.
Keywords: distribution, determinants, health-related states or events specified populations
Also a scientific study of what befalls or happens to a population.
Talk about th
Public health?
It is the process of promoting health, preventing disease, prolonging life and improving quality of health through the organized efforts of society
What is distribution of health states and events?
- refers to a description of the frequency and pattern of health events in a population
- the frequency refers to the number of occurrences of health related events in a population within a time period. It is measured by rates and risks of health events in a population
- pattern refers to the occurrence of related events by personal characteristics, place and time
Determinants of health related events or states?
Also known as risk factors or protective factors depending on which health- related events they are associated with
Health related events?
Refer to health outcomes (eg death, illness and disability) as well as positive health states (eg survival and reduced risk of stroke), and the means to improve health
The epidemiological approach 5W’s
Who- person
Where- place
When- time
Why- cause
What- case discussion
Fundamentals to know about a disease in a population are who, when and where
Use of epidemiology
- to identify factors that can affect the occurrence of the disease
- to access the effectiveness of preventive and therapeutic treatments
- to access the impact of health care services
- to predict future health care needs
Exposure?
It is the risk factor that we are investigating, which may or may not be the cause
Aka: independent variable
Outcome?
It is the disease or event or health- related state, that we are interested in.
Aka: dependent variable
Methods of carrying out an epidemiological study
- Observational
Surveillance and descriptive studies are used to study distribution
Analytic studies are used to study determinants (causes, risk factors) - interventional or experimental
Descriptive study falls under observational studies
A study in which distribution of an exposure and/or an outcome are examined without any attempt by the investigator to influence them
Interventional study/ experimental study
A study designed to test a hypothesis by modifying an exposure within the study population
This study has interventions
Case report
- most simple possible report where only one person is looked at
- single clinical subject
- information is obtained from the past and present and the future is also taken into consideration
- can give information on the first time the new disease comes to light
Disadv:
- only one person is considered in a case report
Case series
- a group of clinical subjects with the same disease are picked
- shared similarities can be looked at thereby providing a list of diagnostic criteria
Disadv
All we have are cases ie people with the disease. There are no controls ( non- disease people)
Cross sectional study aka prevalence study
- a study in which the prevalence of an exposure and/or an outcome are measured in a given population at a specified point in time.
- it can be descriptive or analytic
- at a single point you are taking a snapshot of a condition in a particular population. Hence, you are looking at people who have and those who do not have the disease
- there is no incidence just prevalence
Disadv: one is unable to tell which symptom came first but you will have information on the disease
NB: in cross sectional, we are studying the exposure and outcome in individuals who have the condition not in non diseased people
Case control study
- a study involving individuals with and without the outcome of interest are identified
- it is a retrospective study where the outcome is known but the exposure is not
- does not involve incidence nor prevalence
Cohort studies
- a study in which one or more groups of individuals are followed up over a period of time to determine the frequency of a particular outcome in a group
- aka : confirmation study
- opposite of case control since the outcome isn’t known
- has incidence but no prevalence
Disadv: you have to exclude people who have the disease
Pathogen
Refers to a disease causing organism
Pathology
Refers to the scientific study of a disease
Etiology
refers to the causative agent of a disease
Infection
Refers to the invasion or colonization of the body by a pathogenic organism
Disease
Refers to the abnormal state in which all or part of the body is not functioning properly
Host
Refers to organisms that shelters and supports the growth of pathogenic organisms
Control/ controlling diseases
- refers to the reduction of disease incidence, prevalence, morbidity or mortality to a locally acceptable level as a result of deliberate efforts; continued intervention measures are required to maintain the reduction. Eg: diarrheal diseases
NB: for control and elimination of disease continuous measures are needed to prevent re- establishment of disease or infection
Elimination or disease
Reduction to zero of the incidence of a specified disease in a defined geographical area as a result of deliberate efforts; continuous intervention measures are required. Eg: neonatal tetanus
NB: for control and elimination of disease continuous measures are needed to prevent re- establishment of disease or infection
Elimination of infections
Reduction to zero of the incidence of infection caused by a specific agent in a defined geographical area as a result of deliberate efforts; continued measures to prevent reestablishment of transmission are required. Eg measles, poliomyelitis
Eradication
Permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts; intervention measures are no longer needed. Eg: smallpox
Extinction
The specific infectious agent no longer exists in nature or in the laboratory
Eg: none
Normal Flora
Refer to microorganisms on or in a host, but do not cause disease
They can be transient or resident
Nose- S. Aureus
Skin- S. Aureus and S.epidermis
Urogenital- S. Saprophyticus
Intestines- E. Coli, enterobacter, Klebsiella, Serratia
Microbial antagonism
Belief that normal Flora benefits a host by preventing overgrowth of more harmful microbes
Types of relationship in Flora
Symbiosis: close relationship between two different organisms
Commensalism (+,0) : one organism benefits but the other is unaffected (harmless). Eg: remora fish and shark
Mutualism (+,+): both organisms benefit from each other (helpful) Eg: normal Flora and humans
Parasitism: one organism benefits whilst the other is harmed. Eg: roundworms, ticks, leeches
Opportunism : organism dosent cause disease unless appropriate condition exists ( potentially harmful) eg bacteria such as E. coli, S. Aureus
Classifying diseases
- based on transmission: communicable and non- communicable diseases
- based on frequency of occurrence: sporadic, endemic, epidemic, pandemic
- based on severity: acute, chronic, subacute, latent
Based on transmissibility
- communicable diseases refers to diseases transmitted directly or indirectly from one host to another
Contagious diseases refer to diseases that spread easily from one person to another
Eg: Ebola, Covid-19, HIV - non- communicable diseases refer to diseases that do not spread from one host to another
Eg: diabetes, Alzheimer’s disease, osteoporosis
Based on frequency of occurrence
Sporadic: Occur irregularly, harphazardly from time to time and generally infrequently. Eg: cases of certain infectious diseases
Endemic: the occurrence in a community or region of cases of an illness, specific health related behavior clearly in excess of normal expectancy
Pandemic refers to an epidemic occurring worldwide, or over a wide area, crossing international boundaries and usually affecting a large number of people
Eg ebola
Based on severity
Acute: develops quickly but last for a short duration
Chronic: develops slowly but lasts for a longer duration
Subacute: in between acute and chronic
Latent: causative agent remains inactive for a period of time and then becomes active to produce symptoms
Types of infection
Primary infection: acute infection caused by initial illness
Secondary infection/ caused by opportunistic microbe after host immune system is weakened by primary infection
Subclinical infection: does not cause noticeable disease
Stages of disease development
Stage 1: Incubation period- no signs or symptoms
Stage 2: prodromol period- mild signs and symptoms. The symptoms may not be specific but distress and discomfort can be felt. Normal activities still go on
Stage 3: illness - death can occur since the immune system is down and treatment can fail
Stage 4: Period of decline
Stage 4: Period of convalescence- gradual recovery of health and strength after illness or injury
Reservoir of infection
Mode of transmission
Theee types of reservoir: humans, animals and non- living things
Routes/
Contact: direct, indirect or droplet
Vehicle: eg housefly
Vector
Nosocomial infections
Infection acquired during the course of stay in a hospital, nursing home or other health care facility
_ common Pseudomonas sp.
- introduced to the body via surgery or catheter
- direct contact with other patients or staff predisposes one
- compromised hosts are most susceptible
A community
Refers to a group of people who share a common interest.
Commonly cited in the definition of community are geography, culture and social stratification
Community diagnosis
Refers to a quantitative and qualitative description of the health of citizens and the factors which influence their health
Importance of community diagnosis
- to act as a data reference for the district
- to provide an overall picture of the local community and the resident’s concerns
- to suggest priority areas for intervention and the feasible solutions
- to indicate the resource allocation and the direction of work plans
- to create opportunities for inter sectoral collaboration such as veterinary services or evirkmental protection agency and media involvement
- to form basis of setting indicators for health evaluation
- discuss the data with concerned people including the community leaders and appropriate health inter should be planned
- implement and evaluate the results of intervention
