Reservoir + Microbial Flashcards
What is the train of transmission
Infectious agent; reservoir; portal of exit; mode of transmission; portal of entry; susceptible host
Bacteria - animal - mouth - contact - cut in the skin - anyone (child, babies)
Exposure and Transmission
Exposure; introduction of a new pathogen into a susceptible population
Between reservoir population that can go vice versa to the susceptible population
Transmission: Adoption, establishment, and dissemination in the susceptible population. Requires a pathogen that can adapt to, and transmit between the host
What is a reservoir?
Habitat or pop. in which infectious agents normally lives, grows and multiples
Maintain pathogens over time
What does reservoir not mean…
Ill, not all sick animals are reservoirs (can be sick but may not be able to pass the disease)
If asymptomatic; then we consider it a carrier
An individual can be killed by the agent, but the population maintains the agent
Examples of reservoirs
FelV - cats = reservoirs
Measles Humans = reservoirs
Lepto - Rodents = reseervoirs
Portal of exit
The method the pathogen uses to leave the body of the host
Mode of transmission
Vertical and Horizontal
Vertical transmission
Infection at fecundation and transplacental, transovarial or perinatal
Infection at fecundation and transplacental
Infection at fecundation: virus can attach to spermatozoa or oocyte
Transplacental infection: in utero, through the placenta
Transmission of the egg: Transmission of the pathogen during the egg development
transovarial
Passage of pathogen from the adult female to eggs through the ovaries of an arthropod
Perinatal
At parturition, through the colostrum/milk
Horizontal Transmission
Indirect Vs Direct
Indirect: Any sort of intermediary either animate or inanimate (Distance, intermediary; longer period of time) (
Direct: reservoir directly to a susceptible host Limited space; Without intermediary; short time period)
Direct contact
Contact: skin, mucous membrane, brutal
Droplet, airborne
Wet, large, and short-range aerosols, like sneezing, coughing or talking
Considered to be a form of direct
transmission because disease agents do not generally survive for extended periods within aerosolized particles.
Waterbone (through gills)
Indirect: Vehicle
Common vehicle: Water, food, soil
Fomites - objects that can be contaminated and transmit disease on a limited scale - knife
Indirect: vectors
Vector: Arthropods who carry and transmit pathogens
Mechanical vector (indirect)
an animal that carries a pathogen from one host to another without being infected itself
Biological vector(indirect)
the pathogen undergoes changes or multiplies while in the vector
Portal of entry
The method the pathogen uses to enter the body of the susceptible person or animal
Most of the pathogens cannot go through the intact skin * Animals are well protected (See microanatomy)
What is the most efficient portal of entry
Eyes
Susceptible host
Member of a population who is at risk of becoming infected by a disease
What is a building block of genetic material
Nucleotide is a 3 group compounded composed of
- nitrogenous bases
-carbon sugar (ribose or deoxyribose) - up two three phosphate groups
Purines
Adenine and Guanine
consist of two joined carbon rings with 5 and 6 members
(Elements in the nitrogenous base are labeled 1-9)
Pyrimidines
Cytosine, Thymine and Uracil
Have a six carbon ring
(Elements in the nitrogenous base are labeled 1-6)
Nucleoside
2 elements
Nucleotides
3 elements
Structure of nucleic acids
- The sugar is connected to the nitrogenous base via position 1’
- The nitrogenous base is linked to
position 1’ of the sugar by a glycosidic
bond from N1 of pyrimidine and N9 of purine
A matched to
T with 2 H bonds
G matches to
C in 3 H bonds
What way is a sequence read?
5’ to 3”
DNA characteristics
Double Stranded
Deoxyribose
Thymidynic acid\
A-T pairing
Nuclear location
Stable
RNA
Single-stranded
Ribose
Uridynic acid
A-U pairing
Cytoplasmic location
Labile
Transcription in Bacteria
Transcription begins
Ribosomes begin translation
Degradation begins at 5’ end
RNA polymerase terminates at 3’ end
Degradation continues, ribosomes complete translation
Transcription in animals
Transcripition starts’ 5’end is modified
3’ end of mRNA is released by cleavage
3’ end is polyadenylated
mRNA is transported to cytoplasm
Ribsomes translate mRNA
Prokaryotic
Single RNA polymerase
no introns
Polycistronic
No Polyadenylation
No 5’ c
Eukaryotic
RNA polymerase
I, II, III
Introns removed
Monocistronic
Polyadenylation at 3’ end
Methylated cap at 5’ end
Mutations
Changes the sequence of DNA (any base pair can be mutated)
Spontaneous mutation
Naturally occurring alterations in the DNA due to slippage in natural processes
Background ~10-5-10-6 locus/generation bacteria
Induced Mutation
Mutagens
occur due to physical or chemical agents → modifying a particular base or being incorporated into nucleic acid
Silent Mutation
Silent mutations are mutations in DNA that do not have an observable effect on the organism’s phenotype
Missence mutation
Change in codon → change in AA → change in protein function
Non-sense mutation
coding codon –> termination (stop) codon
resulting in premature termination
Frameshift mutation
Inserting or deletion of nucleotide bases in numbers that are not multiples of three
Transformation
Acquisition of new genetic markers by incorporation of added DNA
Conjunction
“mating” between two bacterial involving transfer genetic material
Transduction
transfer of bacterial gene from one to another by a phage
Transposition
movement of a transposon to a new site in the genome
