Bio251 Epidemiology, pathology, and virulence

exam 3

Symbiosis

Relationship between two organisms where at least one organism benefits

Mutualism

Both organisms benefit

Example of mutualism

E.coli in the intestines

Commensalism

one organism benefits while other is unaffected

Example of commensalism

S. epidermidis on the skin

Parasitism

one organism benefits while other is harmed

Example of parasitism

pathogenic organisms

Normal microbiota

microorganisms that establish a permanent residence

Normal microbiota do not cause disease usually

True

Which microbiota include opportunistic pathogens? Normal or Transient?

Normal

Host factors affect normal microbiota

True

Transient Microbiota

Microorganisms that may be present for days, months, weeks but then disappears

Transient microbiota may or may not cause disease

True

Microbial antagonism

members of the microbiome protect the host from colonization by pathogens

How do microbial antagonism protect the host

compete for nutrients and space, production of harmful subtances, and effect conditions in the surrounding environment

Infection

invasion or colonization of the body with oathogeic microorganisms

Microorganisms dont have to carry out a part of their life cycle in the host body when thinking of infection

False

Disease

any change in health caused by an infection

Pathology

science study of disease

Etiology

causative agent of disease

Pathogenesis

manner in which a disease develops and affects the body

In Koch’s Postulate, the same pathogen must be present in every case of the disease

True

In Koch’s Postulate, the pathogen doesnt have to be isolated from the disease host and grown in pure culture

False

In Koch’s Postulate, the pathogen from the pure culture doesnt have to cause the same disease when put in a healthy host

False

In Koch’s Postulate, the pathogen must be isolated again from the inoculated animal and must be the original organism

True

Culture requirements are an exception to Koch’s postulates (can’t grow in pure culture or artificial media)

True

An exception of Koch’s Postulates is: multiple pathogens may cause the same signs and symptoms

True

Some pathogens can cause multiple disease conditions is an exception of Koch’s postulates

True

An exception of Koch’s postulates is lack of a non human host

True

Symptoms

Changes in the body that the patient can feel and can’t be observed

Signs

Changes in the body that can be measured in the patient

Syndrome

a specific group of signs/symptoms that may always accompany a particular disease

Communicable disease

A disease in which an infected person transmits an infectious agent to another person (Directly/Indirectly)

Contagious disease

highly communicable disease that can spread easily and quickly from one person to another

Noncommunicable disease

Not spread from host to host

Contact transmission

spread of a disease agent by contact

Direct contact transmission

transmission by physical contact with an infected person

Indirect contact transmission

transmission by a nonliving object (fomite)

Fomite

infected NON-living object

Droplet transmission

transmission by droplet nuclei that travel LESS than 1 meter

Vector

animal that carries pathogens from one host to another

Mechanical transmission

passive transport of pathogen on body

Biological transmission

active process of pathogen on body

Vehicle transmission

spread of a disease agent by a medium

Waterborne transmission

transmission by contaminated water

foodborne transmission

transmission by food

Airborne transmission

transmission by droplet nuclei that travel MORE than 1 meter

Small aerosols can’t remain in the air

False

Masks can’t catch droplets or aerosols

False

If you get an infection from food what type of transmission is it?

foodborne transmission

Acute disease

develops rapidly but lasts only a short time

Chronic disease

developes slowly but its often less severe likely to continue or recur for long periods

Latent disease

causative gaent remains inactive for a time but then becomes active to producee the disease symptoms

Subclinical disease

no noticeable illness

Local infection

Invading microorganisms are confined to a relatively small area of the body

Systemic infection

Invading microorganisms are spread throughout the body (blood or lymph)

Primary infection

acute infection that causes the initial illness

Secondary infection

infection caused by an opportunistic pathogen after the body’s defenses have been weakend by a primary infection

Incubation period

period between intial infection and the appearance of signs and symptoms

During the incubation period the microbes increase but no signs or symptoms appear

True

Prodromal period

Period of early mild symptoms in some diseases

The prodromal period is relatively long

False

Period of illness

disease is most severe it ends when the host immune system starts to overcome the pathogens

Period of decline

signs and symptoms subside but are still present

Patient is vulnerable to secondary infection during the period of decline

True

Period of convalescence

Body returns to pre-disease state

What period of disease has no more signs or symptoms?

Period of convalescence

The doctor indicates that Jason should start to feel better in a few days. But he needs to stay hydrated. Which stage of disease is Jason currently in?

Period of illness

Epidemiology is the study of where and when disease occur and how disease is transmitted

True

Descriptive epidemiology

collecting all data to describe the occurence of the disease (affected individuals and time and location)

Incidence

number of people who develop a disease during a particular time period

Prevalence

number of people in a ppopulation who have a disease at a specific time regardless of when it first appeared

Sporadic disease

occurs only occasionally

Endemic disease

constantly present in a population

Epidemic

many people in a given geographic area acquire a disease in a short period of time

Pandemic

worldwide epidemic

Analytic epidemiology

analysis of a particular disease to determine the probable cause (case-control and cohort method)

Case-control method

compare a group of ill people to an unaffected group; uses statistics to determine which factors may have contributed to illness (sick vs. not sick)

Cohort method

compare a group of people who had contact with the agent of disease and one group that has not (exposed vs. not exposed)

Experimental epidemiology starts with a hypothesis about a particular disease (test hypothesis with a group of people)

True

Pathogen

disease causing organism

Pathogenicity

ability of an organism to cause disease by overcoming host defenses

Virulence

degree of pathogenicity

To cause illness, microorganisms have to gain access to a host

True

Mucous membrane

respiratory tract, gastrointestinal tract, genitourinary tract, conjunctiva

Skin

hair follicles and sweat ducts

Parenteral route

wound infections

Organisms don’t have a preferred portal of entry

False

ID50~infectious Dose

How many cells/virions need to enter the body to cause illness in 50% of the population

Relative virulence

How easily does the organism cause illness under certain conditions

A lower ID50 means what

fewer organism required to cause illness; more easily causes infection

Adhesins (anchor molecules) on bacterial cells

binds to receptors on the host cell

Examples of biofilms

dental plaque, shower scum, catheters

capsules

prevent recognition by host immune system

Cell wall components play a part in envading or penetrating host defenses

True

enzyme coagulase

clot blood

enzyme kinase

digest blood clots

enzyme hyaluronidase

breaks down hyaluronic acid

enzyme collagenase

breaks down collagen

enzyme IgA protease

breaks down IgA anitbodies