ch. 14 epidemiology pt. 1

pathology meaning

the scientific study of disease

etiology meaning

cause of a disease

pathogenesis meaning

how disease develops

what types of changes on host are cuased by disease

structural and functional

what is an infection

invasion and/or colonization of body by pathogenic organism

what is a disease

when an infection results in a change from the normal healthy state of an individual

what is transient microbiota

microbiota present for days, weeks or months

what is normal/resident microbiota

microbiota permanently colonizing the host

what is symbiosis

‘living together’, an association between two or more species

what are the three types of symbiosis

• commensalism

• mutualism

• parasitism

what is commensalism

one organism benefits, and the other is unaffected

what is mutualism

both organisms benefit

what is parasitism

one organism benefits at the expense of the other

what are some areas of the body that are normally devoid of normal microflora

• ears

• sinuses

• internal eye

• bone marrow

• muscles

• glands

• brain and spinal cord

• ovaries and testes

what are some areas of the body where you typically find microflora/bacteria

• GI tract

• skin

• colon

what are fetuses free of?

microbes, sterile

what is increased in numbers in a woman’s vagina prior to birth

lactobacilli

what are the first microbes that a newborn comes into contact with

lactobacilli

what microbes are newborn intestines predominant with

lactobacilli

after birth, what are newborns established with and how

normal flora from:

• skin to skin

• inhalation of microbes from air

• ingestion of microbes from food

what are opportunistic microbes

part of your resident/transient microflora that don’t normalyl cause disease but can under certain conditions

what are the conditions that resident'/transient microflora can cause disease in

1. failure of host’s normal defenses

2. microbe gets into wrong part of body

3. disturbances in normal microflora

what are examples of a host’s normal defenses failing and leading to resident/transient microflora to cause disease

• immunocompromised (AIDS)

• immunosuppressive drugs, radiation therapy

• young/old age, stress

what are examples of a microbe getting into the wrong part of the body and leading to resident/transient microflora to cause disease

• E.coli entering urinary tract/surgical wounds instead of inestinal tract

what is an example of disturbance in normal microflora and leading to resident/transient microflora to cause disease

superinfections - caused by antibiotics

what is microbial antagonism

normal flora benefit host by protecting them from overgrowth of more harmful microbes

what are examples of ways microbial antagonism is achieved

• competes for nutrients

• produce susbtances toxic to invading microbes

• altering the local pH

• competing for oxygen supply

what are some examples of microbial antagonism

1. candida albicans and the human vagina (secretes acid)

2. E.coli and the human intestines (secretes bacteriocins)

what are probiotics

live microbial cultures applied to/ingested and areintended to exert a beneficial effect on the host

what are some examples of probiotics

ingestion of lactic acid producting bacteria

what is caused by ingestion of lactic acid producing bacteria:

• alleviate diarrhea

• prevent colonization during antibiotic treatments

• available in liquid forms

what are the four classifications of infectious diseases:

1. signs and symptoms

2. frequency of occurrence

3. severity and duration of disease

4. extend of host cell involvement

what is a symptom

a change in body function that is felt only by a patient as a result of disease, subjective

what is a sign

a change in the body that can be measured or observed as a result of disease, objective

what are examples of signs

swelling, redness, vomitting, rashes, fever

what is a syndrome

a specific group of signs and symptoms that accompany a disease

what is incidence

fraction of a population that contracts a disease during a specific time

what type of cases do incidence rates only take into account

new cases

what can the incidence rate be an indicator of

spread of disease

what is prevalence

fraction of a population having a specific disease at a given time

what does prevelance rates take into account

both old AND new cases

what can the prevalence rate be an indicator of

how serious and how long diseases affects a population

what does morbidity and mortality indicate within a population

seriousness of disease

what is morbidity

number of people affected by a disease during a set period

what is mortality

number of people that die from a disease during a set period

how do you obtain the mordbidity rate

number of people affected / 100,000 perople per year

how do you obtain the mortality rate

number of deaths / 100,000 people per year

what is communicable disease

a disease that is spread from one host to another

what are examples of communicable disease

• chickenpox

• measles

• gentical herpes

• typhoid fever

• tuberculosis

what is contagious disease

a disease that is easily spread from one host to another (airborne)

examples of contagious disease

• chickenpox

• measles

noncommunicable disease meaning

a disease that is not transmitted from one host to another

examples of noncommunicable disease

• tetanus

• valley fever

• cancer

• malaria

what is sporadic disease

disease that occurs occasionally in a population

example of sporadic disease

typhoid fever in US

endemic disease meaning

disease constantly present in a population

example of endemic disease

the common cold

epidemic disease meaning

disease acquired by many hosts in a given area in a short time

examples of epidemic disease

• influenza

• ebola

pandemic disease meaning

worldwide epidemic

example of pandemic disease

AIDS

which type of occurences of disease classification is present at low levels in a population

endemic

which type of occurences of disease classification has low morbidity and low mortality

endemic

which type of occurences of disease classification is not enough to be considered a public health threat

endemic

which type of occurences of disease classification has higher morbidity and higher mortality rate

epidemic

which type of occurences of disease classification causes a public health threat

epidemic

when do endemic disease turn epidemic?

1. emergency of super virulent strain of pathogen

2. lack of immunity in the population

3. dramatic increase in population density

4. insufficient health precautions

what rate of vaccination should be aimed to achieve herd immunity

at least 90% of population vaccinated

epidemics of ___ ____ occur in central africa every 5-12 years

mengicoccal meningitis

factors that contribute to cyclic epidemics

1. environment

2. other diseases

3. lack of herd immunity

4. strain virulence

5. timing

nature and spread of an epidemic depends on what?

where the source of the pathogen comes from and how it reaches a host

what is a common source outbreak

contact with contaminated substance

examples of common sources for a common source outbreak

1. contaminated water supply

2. improperly handled food

propagated epidemic

direct person to person contact

what is an acute disease

symptoms develop rapidly, only lasts short period of time

example of acute disease

influenza

chronic disease meaning

disease develops slowly, but recurrent or continual for long period of time

examples of chronic disease

• mononucleosis

• tuberculosis

• hepatitis b

sub-acute disease meaning

symptoms between acute and chronic

sub-acute disease example

gingivitis

latent disease meaning

disease with a period of no symptoms prior to production of symptoms

example of latent disease

varicella-zoster virus (shingles)

types of extent of host involvement

• local infection

• systemic (generalized) infection

• focal infection

local infection meaning

pathogens are limited to a small area of the body

examples of local infection

• boils

• abscesses

• bladder infection

systemic (generalized) infection meaning

an infection throughout the body

examples of systemic/generalized infection

measles

focal infection meaning

infection that began as a local infection, spreads in lymph or blood to a specific area

example of focal infection

bacterial endocarditis

septicemia meaning

growth of bacteria in the blood

what is septicemia also known as

blood poisoning, systemic infection

what is bacteremia

bacteria in the blood

toxemia meaning

toxins in the blood

viremia meaning

viruses in the blood

primary infection

acute infection that causes the initial illness

secondary infection

opportunistic infection immediately after a primary (predisposing) infection

example of secondary infection

pneumocystis pneumonia - consequences of AIDS ifnection

subclinical disease meaning

no noticeable signs or symptoms (inapparent infection)

sublicinical disease example

poliovirus and hepatitis a

predisposing factors

make the body more susceptible to disease