chap 14 Flashcards
infection v. disease
infection - process of getting the disease
disease - actual process of sickness
virulence v. pathogenicity
virulence - harmfulness
pathogenicity - how agent causes disease
normal microbiota
bacteria in the human body
- microbes colonize nonsterile areas/areas exposed to
environment(skin, oral and nasal cavities, lung)
comes from birth(while coming out pick up normal microbiota)
what does the presence of bacteria in sterile areas signal?
infection
transient microbiota
microorganisms that are only temporarily found in the human body
- ex pathogens
how does normal microbiota help defend against other infections?
- normal microbiota exhibit microbial antagonism/competitive exclusion
- occupy space, compete for nutrients, produce agents, modify the microenvironment
what type of relationship does host and normal microbiota have?
typically commensalism(one benefit and one is fine)
what is mutualism and paratism?
mutualism - both benefit
parasitism - one benefit one harmed
opportunistic pathogens
normally not harmful but when compromised can cause diesease
opportunistic pathogens v primary pathogens
opportunistic - normally not harmful but when compromised can cause disease
primary - not usually in body but if inside will always try to cause disease
koch’s postulates
- same pathogen present in all cases
- isolation of pathogen(pure culture)
- give pure culture to susceptible host
- re-isolate now sick host
exceptions to koch’s postulates
- healthy individual can carry and show asymptomatic
- some microbes not culturable
- similar symptoms and diseases can be from same
pathogen - same pathogen can cause different diseases
- viruses cant be cultured, some have no animal host, and
some are latent
symptoms vs. signs
symptoms - subjective (malaise, headache, dry throat)
signs - objective (measurable, fever, rash, swelling)
syndrome
group of signs and symptoms that occur together and characterize a condition
communicable disease
can directly/indirectly spread from host to host (measles, chickenpox, flu, std)
non communicable disease
can not spread from host to host (tetanus)
contagious disease
can easily spread from person to person
incidence vs. prevalence
incidence - rate of people that get disease during certain time (indicate spread)
prevalence- number people get disease in specified time period (old and new cases; indicate seriousness)
frequency of disease
- sporadic - occurs infrequently
- endemic - always present (flu)
- epidemic - rapid development in specific area
- pandemic - worldwide epidemic
severity/duration of a disease
acute disease - symptoms develop rapidly(flu)
chronic disease - disease develop slowly (tb)
subacute disease - symptoms between acute and chronic
latent disease - disease w period of no symptoms
herd immunity
immune individuals acta s barrier to spread of infections(does not work for non communicable disease)
what is the RO value
the avg number of people who will contract disease from one person w disease
different extent of infections
local - limited, confined to specific area
systemic - spread through whole body (circulatory/lymphatic)
focal - spreads from local infection to specific parts of body (teeth, tonsil)
sepsis - inflammatory condition due to presence of toxin/bacteria (ex. septicemia)
septicemia/bacteremia/sepsis
blood poisoning by bacteria
types of infection
primary infection - causes initial illness
secondary - caused by opportunistic pathogen after primary
subclinical - no noticeable signs or symptoms of illness
how can the body be more susceptible to disease
- due to genetics(ex. female and male), inherited traits(sickle cell), climate, weather, fatigue, age, lifestyle, and chemotherapy
development of disease
- incubation(no signs or symptoms)
- prodromal(mild signs or symptoms)
- period of illness(most severe signs and symptoms)
- period of decline(signs and symptoms)
- period of convalescence
reservoir of infections and the different types
- source of disease microbes
human - can show symptoms or not(hiv, hepatitis std)
animal - zoonoses (rabies, lyme disease, ebola)
non living - soil, water (tetanus, cholera)
transmission of disease(contact)
direct contact - physical contact btwn source and host
indirect contact - via inanimate object(fomite)
droplet contact - short distance via sneezing and coughing ( about 1 meter)
fomite
object and materials that can carry disease
transmission of disease(vehicle)
waterborne - contaminated(fecal) to water treatment to system compromised
airborne - dust particles and pet dander
foodborne - contaminated food
storage at improper temperature
unsanitary handling of food
also blood and drugs
- feceal-oral transmission
- congenital transmission(mother to child)
vector
when animal(normally insects) carry and transfer disease
mechanical transmission - passive via body parts
biological transmission - involves parasite life cycle
what are HAIs(health care associated infections)
- acquired as a result of receiving treatment fr healthcare facility(4-5% patients)
what do hais result from
microorganisms in hospital - opportunistic pathogens (they more likely resistant to drugs)
compromised host - resistance to infection impaired by disease, therapy or burns(can be due to broken skin or mucous membranes and suppressed immune systems)
chain of transmission - direct contact from patients; indirect(fomites and airborne)
precautions for hais
universal precautions - to reduce transmission of microbes in health care and residential settings
standard precautions - basic, minimum; applied to all levels (ex. aseptic techniques, handing of contaminated materials, frequent handwashing, use of isolation rooms and wards, ppe, educate staff)
transmission based precautions - supplement standard in individuals w know/suspected infections that are highly transmissible (ex. contact, droplet(short distance), and airborne(long distance) precautions)
emerging infectious diseases
new or changing, show an increase in incidence in the recent past or show potential to increase’
- can be caused by virus, bacteria, fungus, protozoan, or helminth(75% zoonotic of viral origin and vector borne)
criteria to identify eid
- distinctive disease symptoms
- improved diagnostic techniques allow id of new pathogen
- local disease is widespread
- rare disease becomes common
- mild disease become more severe
factors contributing to eid
- genetic recombination/evolution
- misuse of antibiotic/pesticides
- climate change
- increase human transportation
- ecological changed
- public health failures
epidemiology
- study of where and when disease occur and how it’s transmitted
what is epidemiology used for
- determining etiology disease
- find demographic data, socioeconomic status, common histories to see why spread
- develop methods for controlling disease(control of reservoirs, food inspection, sewage disposal)
- assemble data and graphs to outline incidence (determined frequency; test effectiveness of disease control)
types of epidemiology and examples
- descriptive epidemiology: collection and anaysis of data shoe occurrence of disease
- john snow: map cholera to find source - analytical epidemiology: analyze particular disease to find cause
- Florence nightingale: use stats to show high
mortality rate of typhus in soldiers in warfare - experimental epidemiology: involve hypothesis and controlled experiments
- Semmelweis: handwashing decreased incidence of childbirth fever (puerperal sepsis)
- clinical trial: test and control group
case reporting
health care workers report specified disease to local, state and nation offices(est chain of transmission)
- nationally notifiable infectious diseases - physicians are required to report occurrence
cdc
-collects and analyzes epidemiological information in u.s
- publishes morbidity and mortality weekly report
morbidity v mortality
rate of morbidity - rate of infection/sickness
rate of mortality - rate of death
