Chapter 14

The study of disease

pathology 

The study of the cause of a disease

etiology

Invasion or colonization of the body by pathogens

infection

an abnormal state in which the body is not performing normal functions

disease

the process in which a disease or disorder develops; the process in which an infection leads to a disease

pathogenesis

take up temporary resident in and on the human host

transient microbiota

Where in or on the human body would you expect to find transient microbiota?

skin, mouth, GI tract

Always present in and on the
human host

resident microbiota

Relationships between host and microbes

symbiosis 

One organism benefits, and the other is unaffected

commensalism

Both organisms benefit

mutualism

One organism benefits at the expense of the other 

parasitism 

Infectious diseases are caused by pathogens

germ theory

Sequence of experimental steps relating a specific microbe to a specific disease with specific symptoms

Koch’s Postulates

What helps determine the cause of an infectious disease?

Koch's Postulates

The same pathogen must be present in:

every case of the disease

The pathogen must be isolated from the

diseased host and grown in pure culture

The pathogen from the pure culture must cause the disease when its inoculated in a:

healthy host

The pathogen must be isolated from the inoculated animal and must be shown to be the

original pathogen 

Changes in the body that are felt by a patient, subjective, non measurable 

symptoms

Changes in the body that can be
measured or observed, objective

signs

Fatigue, pain, itching, dizziness,
soreness, and nausea

symptoms 

Blood pressure, heart rate, weight
loss, fever, vomiting

signs

A specific group of signs and symptoms that
accompany a disease

syndrome

A disease that is spread from one host to another

communicable disease

A disease that is easily and rapidly spread

contagious disease

A disease that is not spread from one host to
another

noncommunicable disease 

Tuberculosis, Covid-19 by Sar-CoV-2, and common cold are examples of a 

contagious disease 

Tetanus, Diabetes, Stroke, and COPD are examples of a 

noncommunicable disease 

The number of new cases of a disease during a specific time period

incidence 

The number of people who develop a disease at a certain time and those that are affected or recovering; considers both old and new cases

prevalence

Disease that occurs occasionally

sporadic disease

Disease is constantly present in a population

endemic disease

Disease acquired by many people in a
given area in a short time

epidemic

Worldwide epidemic, epidemic on multiple continents/international

pandemic

Symptoms develop rapidly but the disease last only a few days

acute disease 

Example of an acute disease

influenza

Example of a chronic disease

cancer

Symptoms develop slowly; long duration and mild symptoms

chronic disease

An intermediate between acute and chronic

subacute disease

Causative agent is inactive for a time, activation occurs and produces symptoms

latent disease

Immunity where the entire population is protected, accomplished through vaccinations

herd immunity 

pathogens are limited to a small area of the body

local infection

An infection throughout the body

systemic infection

Uncontrollable spread of microbes in the
blood

septicemia

Bacteria in the blood

bacteremia

Toxins in the blood

toxemia

Viruses in the blood

viremia

Infection that causes the initial illness, HIV

primary infection

Caused by opportunistic pathogens after the primary infection, AIDS

secondary infection 

Factors that make the body more susceptible to
disease

predisposing factors

Time between your exposure to the pathogen
and the onset of symptoms and signs

incubation period

Short period after incubation, early stage, mild symptoms

prodromal period

When your body starts producing antibodies, most severe signs and symptoms 

period of illness 

Largest/highest amount of microbes, highest number of antibodies

peak illness

Signs and symptoms subside

period of decline

Body returns to its pre-diseased state, normal function returns (asymptomatic carriers)

period of recovery

A continual source of infection; location of pathogen

reservoir 

People who harbor pathogens and can spread them

human reservoirs 

Animals that naturally carry and transmit
infectious disease to humans

animal reservoirs

Infectious diseases that are
transmitted from animals to humans

zoonoses

Contaminated inanimate things or objects

nonliving reservoirs

Requires close association (touching) between an infected person and a susceptible host

direct contact transmission

Transmission via airborne particles less than 1 meter

droplet transmission

Spreads to host by a contaminated non-living object (Fomite)

indirect contact

Transmission from mother to fetus or newborn during birth

congenital transmission

Transmission by a contaminated inanimate/nonliving reservoir

vehicle transmission 

The spread of infectious diseases through living organisms; typically arthropods

vector transmission 

Arthropod vector supports life cycle of pathogen in its body

biological vector transmission

Arthropod vector carries the pathogen outside of its body

mechanical vector transmission 

An infection acquired in the hospital/clinical
environment

healthcare-associated infection

What are the two most common microorganisms involved in HAIs?

Staphylococcus aureus and Clostridium difficile

The study of where and when diseases occur and how they are transmitted within populations

epidemiology

The number of people or incidence of a specific notifiable disease in a population

morbidity 

The number of deaths from notifiable disease

mortality

Disease in which physicians are required to report the occurrence

nationally notifiable infectious diseases

What are the 3 STDs that are nationally notifiable infectious diseases?

HIV, gonorrhea, and syphilis