Lecture 20: Epidemiology of Infectious Diseases
Eg of emerging diseases since 1982. (5)
HIV, hantavirus, hep c and e, ebola, lyme disease
Father of epidemiology
John Snow
The figure out if a pathogen is new or unknown, you use _____ _______
Koch's postulates
Has a clinical case of the disease
active carrier
4 types of carriers
active, convalescent, healthy, incubatory
A pathogen that infects a host with a rapid and dramatic onset but quick recovery results in a _______ illness
acute
______ carriers carry the pathogen for a short period of time (hrs, days, weeks)
acute
John Snow studied the disease ________
cholera
Well-adapted pathogens live harmoniously with the host, taking what it needs to survive and resulting in a ______ illness
chronic
______ carriers carry the pathogen for an extended period of time (months, years, forever)
chronic
An infectious disease that can be transmitted from person to person
communicable disease
Recovery is also known as _______
convalescence
Someone with herpes and no active lesions would be considered a ________ carrier
convalescent
Has recovered but still carries the disease
convalescent carrier
Epidemiologists use statistics to 1. evaluate _____ ______. 2. monitor ______ ________. 3. determine ________. 4. ______ future issues.
current disease, disease rates, magnitude, anticipate
______ of a disease is the number of cases of an individual disease at a given time period
incidence
Using the _____ and _____ of a disease within a population, some important statistics can be identified
incidence, prevalence
The stage between entry of pathogen and the first expression of signs and symptoms
incubation
Is in the incubation phase of the disease
incubatory carrier
Often considered a type of vehicle transmission _______ _______
indirect contact
Touching of contaminated objects such as cups, stethoscopes, neckties, thermometers, eating utensils are _______ _______
indirect contact
The host becomes infected and the organism begins to grow
infection
5 stages of infection
infection, incubation, prodromal, illness, recovery
Chain of infection steps:
infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, susceptible host
______ ______ results from an infection with a microbial agent
infectious disease
Eg. of epidemic is _______
influenza
The prodromal period is initiated by the ________ immune system
innate
Finding the causative agent involves lab _______ and _______
isolation, determination
Morbidity rate is derived from ______ reports or usage of specific ________
lab, antibiotics
Eg. of an outbreak is ________ disease
legionnaires
Geographic distribution can be looked at with _____ _____ and ______ ______ ________.
remote sensing, geographic information system
The site or location in which the pathogen normally resides, can be animate or inanimate
reservoir
Step 1: Pathogen identification involves looking at 1. ______. 2. _____ _______. 3. _______ or ______ pathogen.
s+s, lab tests, new, unknown
Normal microflora such as ________ and ______ can cause nosocomial infections
s. aureus, s. pneumoniae
A new flu virus that forms with a detrimental effect is the result of antigen _______
shift
The location from which the pathogen is immediately transmitted to the host, either directly or indirectly
source
Eg. of pandemic is _____ ______ in 1918
spanish influenza
A _______ _______ occurs occasionally and at irregular intervals in a human population, ie. bacterial meningitis
sporadic disease
Fomites _____ the pathogen but does not support _______
spreads, reproduction
Epidemiologists use _______ and _______ information systems
statistic, geographic
H1N1 is responsible for ___ flu
swine
T or F: in many cases, a pathogen cannot grow outside a host
t
Most common site of nosocomial infections
urinary tract
In the last century, there has been a huge decline in deaths associated with infectious diseases worldwide due to : (4)
vaccines, antibiotics, public health campaigns, epidemiological monitoring
Infectious disease can be caused by : (4)
virus, bacteria, fungi, protozoan
______ _____ , _______, _____ and ______ Are no longer the great threat they once were
whooping cough, pneumonia, polio, smallpox
_______ are diseases that can be spread from an animal to a human
zoonoses
___% of pts are affected by nosocomial infections
10
Name of road where everyone got cholera
Broad
The onset of nonspecific signs and symptoms, patient is often contagious
prodromal
Carriers can either be : ______ or ______
acute, chronic
Analysis involves looking at many different factors that can contribute to disease: (5)
age, sex, occupation, geography, economic status
After recognition of an infectious disease, the causative ______ must be identified
agent
Pathogen is floating in the air either in a droplet or dust
airborne
Pathogen transmission can occur: (4)
airborne, contact, vector, vehicle
Vector transmission is normally done by an ________ or a ________
arthropod, vertebrate
Most commonly nosocomial infections are ________ infections
bacterial
_____ ____ is an example of a sporadic disease
bacterial meningitis
When the pathogen changes inside a vector eg. malaria. This is considered _________.
biological
H5N1 is responsible for ___ flu
bird
Worst animals for carrying diseases
birds
Mortality rate is derived from ____ _____
death certificates
Touching, kissing, sexual contact, contact with secretions, nursing or through placenta is considered _____ ______
direct contact
Contact transmission can be ____ or _____
direct, indirect
An ______ is when a disease is continuously found in a population, but at a low incidence level
endemic
Nosocomial infection from pt's normal microbiota
endogenous
3 sources of nosocomial infections
endogenous, exogenous, autogenous
An _____ is an outbreak affecting many people at once
epidemic
The study and evaluation of the occurrence, distribution and the control of disease in a given population
epidemiology
Vector transmission can be _______ or _______
external, internal
T or F: all infectious diseases are communicable
f
T or F: most infectious diseases have been erradicated
f
An inanimate object that transmits disease
fomite
An epidemiologist must analyze a disease _________ at single time points
frequency
Many new variants of diseases have developed: eg. (6)
h5n1, h1n1, new CJ, MRSA, food borne, new tb
With RS and GIS you can relate specific _________ to geographical ________.
habitats, regions
When the pathogen is carried IN a vector eg. Black plague in fleas. This is considered ________.
harborage
3 types of internal vector transmission
harborage, biological
Someone with S. pyogenes in their throat but is not sick would be considered a _________ carrier
healthy
Has the pathogen but is not ill
healthy carrier
Pathogens that cause disease in human populations have to grow and reproduce within their _____ of choice
host
A ________ disease is when a disease gradually increases to a level over endemic but below epidemic
hyperendemic
A sudden increase in morbidity of a disease would lead to 1. _________ of a source. 2. ________ to prevent death
identification, measures
The stage at which the disease is most severe and specific signs and symptoms emerge
illness
John Snow lived in ______ in ______ (range)
london, 1849-1854
When the pathogen is carried ON a vector eg. a fly lands on food. This is considered _______.
mechanical
A sudden increase in the _____ of a disease would lead to identification of a source and determine measures to prevent mortality
morbidity
The number of new cases in a population at a given time
morbidity rate
The number of deaths from a disease in relation to the total cases of the disease
mortality rate
______ infections are those acquired at a hospital
nosocomial
An _____ is a sudden, unexpected occurrence of the disease
outbreak
An epidemiologist must determine if they are working with an _____, ____ or ______
outbreak, epidemic, pandemic
A ______is an increase in disease occurrence within a large population over a large area (usually the world)
pandemic
Active exit from the host is typically only done by _____ ______
parasitic worms
______ exit from host is usually done by microbes
passive
2 steps in identification of a pathogen
pathogen identification, the source and/or reservoir
Host susceptibility depends on ________ of organism and ________ _____ of host
pathogenicity, immune system
Surveillance of the disease and its effects in a population help identify ______ of the disease and can help with ______ and ______ strategies
patterns, treatment, containment
Factors influencing emergence of infectious diseases: (6)
population growth and urbanization, travel, changes in agriculture, microbial evolution, modern medicine, economy/politics
_______ of a disease in a population is the proportion of diseases individuals at a given time period
prevalence