One of the partners is inhibited, while the other is not affected in any significant way.
One of the organisms benefits, and the other is unaffected.
Benefits both organisms.
Between two organisms of unlike species in which one of them acts as predator that captures and feeds on the other organism that serves as the prey
One organism gains and tho other is harmed.
Permanently colonize the host
Colonize the host for days weeks or months
How do Normal Microbiota protect?
Compete for nutrients
Alter conditions such as pH, available oxygen
Produce harmful substances
What is Competetive Exclusion?
Covers binding sites so pathogens can't bind
Addition of microbes to the diet in order to provide health benefits beyond basic nutritional value
Benefits of Probiotics?
Restore friendly bacteria in digestive tract
Aid in digestion and absorption of nutrients
Promote proper elimination of waste
Selectively stimulate bacteria of color and improve health of host
Colonization of the body by pathogens
Impairment of normal state of an organizm or any of it's components that hinders the performance of vital functions
Disease that is caused by microorganisms
Non communicable disease
Not transmitted from one host to another
Spread from one host to another
Easily spread from one host to another
Change in body function that is felt as a result of disease
change in body that can be measured or observed as a result of disease
A specific group of signs and symptoms that accompany a disease
may develop long lasting immunity
result in productive infections
disease symptoms result from tissue damage and infection of new cells
viruses continually present in host
Persistent infections caused by?
Integration of viral genome into host genome
decrease of antigenicity of virus
mutation to less virulent and slower reproducing form
three categories of persistent infections
infection is followed by a symptomless period.
During latency what happens?
Virus stops reproducing and remains dormant for some time, Symptoms antivirus -antibodies, and viruses are not detectable.
Reactivation of a latent virus
Infectious particles are again detected
symptoms may be different than originally
Infectious virus can be detected at all times
During a chronic infection is the disease always present?
No. may be absent or present or may develop late
Infectious agent gradually increases in amount over a long period of time
During a slow infection are symptoms always apparent?
no, during the increase they may not be apparent
i.e. retrovirus or prions
Classifications of Disease
Occurs occasionally in a population (irregular)
Sudden and unexpected occurrence of disease usually focal or in a limited segment of the population.
Constantly present in a population
Acquired by many hosts in a given area in a short time
Increase in disease occurrence within large population over wide region
Fraction of a population that contracts a disease during a specific time.
Fraction of a population having a specific disease at any given time.
Koch's Postulates :
Same pathogen must be present in every case of the disease
Pathogen must be isolated from the diseased host and grown in pure culture
pathogen from the pure culture must cause the disease when it is inoculated into a healthy susceptible laboratory animal
pathogen must be isolated from the inoculated animal and must be shown to be the original organism
What disease did Koch search the link between organism and disease?
Anthrax and Bacillus anthracis
What is unculturable taxa
organism cannot survive outside the host
True or false - Pathogens can cause only one type of disease
False. some pathogens can cause several disease conditions
True or False - Some pathogens cause disease only in humans
Source of pathogen
Location from which pathogen is transmitted to host
Reservoir of pathogen
Site or natural environmental location in which pathogen is normally found - can also be the source
harbors pathogen for a short time
Harbors pathogen for long periods of time (months, years, life)
harbors pathogen, but is not yet ill
Has overt clinical case of disease
has recovered from disease, but continues to harbor large numbers of the pathogen
harbors pathogen, but is not ill
transmission from animal to human, can be direct or indirect
Organisms that spread disease from one host to another
What are the four main routes of pathogen transmission?
Direct contact transmission
person to person or person to source or reservoir
Involves an intermediate such as tissues, bedding, utensils, ,etc. (fomite)
large particles that travel (>5 Micro meter travel < 1 meter)
droplet is suspended in air and travels > 1 meter
Can remain airborne for hours or days and travel long distances,
Vehicles are inanimate materials or objects involved in pathogen transmission, (water, food)
Vector Borne Transmission
External (mechanical) transmission
Passive carriage of pathogen on body of vector
No growth of pathogen during transmission
Vector Borne Transmission
Carried within Vector
Pathogen does not undergo changes within vector
pathogen undergoes changes within vector
movement of pathogen to exit
Excretion in feces, urine, droplets, saliva or desquamated cells
How to control epidemics?
(3 part answer)
Reduce or eliminate source or reservoir of infection
Break connection between source and susceptible individual
Reduce number of susceptible individuals
Acquired as a result of a hospital stay
What % of hospital patients are affected by nosocomial infections??
What bacteria usually cause nosocomial infections?