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