Epidemiology of Communicable Diseases Flashcards
The study of the distribution and determinants of healthrelated states or events (including disease), and the application of this study to the control of diseases and other health problems.
Epidemiology
Studies the factors that determine the frequency,distribution, and determinants of diseases in human populations
Epidemiologists
The basic model to study health problems
Epidemiological Triangle
This is produced by exposure of a susceptible host to an noxious agent in the presence of environmental factors that aid or hinder agents of disease.
Disease
The characteristic of an agent that embodies
capability of entering, surviving, and multiplying and causing disease in a susceptible host
Infectivity
The ability to cause a disease
Pathogenicity
T/F All agents, especially biological agents, arepathogenic/can cause disease.
False; Some bacteria are normal microbiota or are normally part of our bodies
The degree of pathogenicity or disease-producing ability of a microorganism
Virulence
T/F The more virulent an organism
is, the more it can possibly cause a disease
True
T/F The more virulent an organism
is, the more it can possibly cause a disease
True
The ability or extent to which a substance is able to stimulate an immune response
Immunogenicity
This refers to the capacity to produce toxin
Toxigenicity
T/F There are organisms that are producing its own toxin that eventually cause the clinical
manifestation of the disease.
True
The ability of bacteria and other
microorganism to resist the effect of an antibiotic to which they were once sensitive
Resistance
The ability of bacteria and other
microorganism to resist the effect of an antibiotic to which they were once sensitive
Resistance
A period in which the infection is present in the
host without producing overt symptoms.
Latency
Means an illness caused by an infectious agent or its toxins that occurs through the direct or indirect transmission of the infectious agent or its products from an infected individual or via an animal, vector or the inanimate environment to a susceptible animal or human host.
Communicable Disease
Communicable diseases that are easily transmitted from one person to another
Contagious Disease
Infectious diseases that humans acquire from animal sources.
Zoonotic Diseases (Ex. Bird Flu)
The time interval between the exposure to the agent and the onset of signs and symptoms
Incubation Period
Interval between the acquisition of the infectious agent by a vector and a vector’s ability to transmit the agent to another susceptible host
Extrinsic Incubation Period
The time in which the infectious agent may be transferred from an infected host to a susceptible host
Communicable Period
The time period between the lodgment of the agent and the period of maximum communicability of the host
Generation Time
The difference between stages of the development of thedisease; whether it is inapparent or severe
Gradient of Infection
This is where there are no visible signs or symptoms
Inapparent infection
Infection with clinical manifestations, high case fatality, and high proportion of disease sequel
Severe Infection
State wherein a host is infected but does not manifest the disease’s signs and/or symptoms
Carrier State
These changes in disease trends within a year; is dependent on environmental conditions; vector density; and behavior of the host
Temporal Trend
These changes in disease trends over several years; observable changes in those susceptible to the disease
Annual Trend
These are gradual changes in the occurrence of disease over long periods of time; may be due to changes in incidence, age distribution, or diagnostic ascertainment
Secular Trend
Diseases that occur only occasionally within the population of a particular geographic area
Sporadic Diseases
Diseases that are always present within the population of a particular geographic area
Endemic Diseases
T/F In Endemics, the disease dies out quickly
False; Disease never dies out completely; It is always present
Greater than usual number of cases of a
disease in a particular region, usually occurring within a relatively short period of time
Epidemic
Occurring in epidemic proportions in many countries simultaneously—sometimes worldwide (Ex. Spanish Flu, COVID-19)
Pandemic Diseases
Certain number of people in the community is
immunized against a specific disease which allows the population who can’t be immunized be protected from the disease
Herd Immunity
Number of new cases of that disease in a defined population during a specific time period
Incidence
Number of cases of the disease existing in a given population during a specific time period
Period Prevalance
Number of cases of the disease existing in a given population at a particular moment in time
Point Prevalence
This is the ratio of the number of people who died of a particular disease during a specified time period per a specified population; also known as Death Rate
Mortality Rate
Usually expressed as the number of new cases of a particular disease that occurred during a specified time period per a specifically defined population
(usually per 1,000, 10,000 or 100,000 population)
Morbidity Rate
Chain of Infection
- A pathogen
- A reservoir of pathogen
- A portal of exit
- A mode of transmission
- A portal of entry
- A susceptible host
Any site where the pathogen can multiply or merely survive until it is transferred to a host
Reservoir
Most important reservoirs of human infectious diseases
Humans/ Human Reservoirs
A person who is colonized with a particular
pathogen but the pathogen is not currently causing disease to that person
Carrier
They carry the pathogen without having the
disease
Passive Carriers
They are capable of transmitting a pathogen
during the incubation period of a particular infectious
disease
Incubatory Carriers
Harbor and can transmit a
particular pathogen while recovering from infectious disease. Pathogen still sheds from patients’ body fluids
Convalascent Carriers
Have completely recovered from the
disease, but continue to harbor the pathogen indefinitely. Pathogen can still be transmitted
Active Carriers
The carrier of salmonella typhi and caused outbreaks of typhoid fever in the area where she prepares food
Mary Mallon
T/F Salmonella can be transmitted through ingestion
True
They are important reservoirs of zoonoses
Animals
Zoonoses is acquired by:
– direct contact with the animal
– Inhalation or ingestion of the pathogen
– Injection of the pathogen by an arthropod vector
Can arthropods be vectors?
Arthropods are involved in the
transmission of infectious diseases
This reservoir contaminated by dust and respiratory secretions
Air
This reservoir can carry spores of bacteria and dried bits of human and animal excretions
Dust
This reservoir can be contaminated by careless
handling
Food and Milk
This reservoir can be contaminated with human and animal fecal matter
Water
These are inanimate objects capable of transmitting pathogens
Fomites
Mode of transmission that involves the transfer of pathogen via infectious droplets
Droplet
Contact
Direct or Indirect
Mode of transmission that involves the dispersal of droplet nuclei (smaller than 5um)
Airborne
Mode of transmission which can be contaminated inanimate objects
Vehicular
Mode of transmission that involves various types of biting insects and arachnids
Vector transmission
Transmission of infection that can be prevented by frequent handwashing
Direct skin - to - skin contact
This can be transmitted by kissing or sexual intercourse; Most STDs are transmitted by this manner
Direct mucous membrane-to-mucous membrane
contact
Ongoing operations or programs aimed at reducing the incidence or prevalence of that disease
Control of an infectious disease
Reduction of case transmission to a predetermined very low level
Elimination of an infectious disease
Achieving a status where no further cases of that disease occur anywhere and where continued control measures are unnecessary
Eradication of an infectious disease
