Disease Transmission & Emerging/Re-emerging diseases

Question 1

Non-transmissible infectious diseases

Answer 1

Person cannot spread the disease to a new person (Tetanus)

Question 2

Source/Reservoir in Direct transmission

Answer 2

Normally are the same thing

In indirect transmission, the source and reservoir are normally different

Question 3

Droplets

Answer 3

Direct transmission

Question 4

Airborne/aerosols

Answer 4

Indirect transmission

Question 5

Transmission involving vectors

Answer 5

Indirect transmission

Question 6

4 main groups of biological transmission

Answer 6

1- Propagative: multiplies, but no change/development (Bacteria)

2- Cyclopropagative: multiplies and changes/develops (protozoa)

3- Cyclodevelopmental: develops but doesn’t multiply (nematodes and trematodes)

4- Vertical: from mother to infant

Question 7

Pathogen associated with surgical incisions

Answer 7

S. aureus

causes wound infections

Question 8

Pathogen associated with urinary catheters

Answer 8

E. coli and other G-

causes UTIs

Question 9

Pathogen associated with IV catheters

Answer 9

S. epidermidis
C. albicans
causes bacteremia and local infections

Question 10

Pathogen associated with needlestick injuries

Answer 10

HBV, HCV, HIV

Causes hepatitis and AIDS

Question 11

Pathogen associated with intubation

Answer 11

Pseudomonas aeruginosa
Klebsiella pneumoniae
Causes pneumonia

Question 12

Pathogens transmitted by Aedes app.

Answer 12

Chikungunya
Dengue
Zika
Yellow fever

Question 13

Disinfectant agents that can kill bacterial spores

Answer 13

H2O2
Formaldehyde
Chlorine
Glutaraldehyde

Question 14

Only compounds that are both disinfectants and antiseptics in healthcare setting

Answer 14

Alcohols

H2O2

Question 15

Sterilization by gamma rays/ionizing radiation

Answer 15

Disrupts DNA

Question 16

Sterilization by microwaves/non-ionizing radiation

Answer 16

Disrupts cell membranes

Question 17

Sterilization by H2O2 plasma

Answer 17

Free radicals interact w the cell membranes, enzymes or nucleic acids

Question 18

Sterilization by ozone gas

Answer 18

Oxidation of cell membranes

Question 19

Sterilization by autoclaving

Answer 19

Denatures and coagulates proteins

Question 20

Sterilization by ethylene oxide gas

Answer 20

Alkylates amino acids, nucleic acids etc.

Question 21

Autochthonous

Answer 21

native to the place where it is found endemically

Question 22

Opportunistic pathogens

Answer 22

Require pre-existing host compromise
Exposure is accidental
Cannot infect and uncompromised host

Question 23

True pathogens

Answer 23

Do not require a pre-existing compromise to infect.
Can infect healthy and imcl’d
Sometimes exposure is accidental

Question 24

Virulence

Answer 24

Damage in a susceptible host due to a host-microbe interaction

Question 25

Persistent infections

Answer 25

Not eliminated by the host immune system Chronic: long duration, slow developing, shedding continues Latent: genome maintained in host without replication. No shedding. (ex. TB)

Question 26

Examples of Chronic persistent infections

Answer 26

Typhoid fever (S. typhi) Leprosy Syphillis

Question 27

Examples of latent persistent infections

Answer 27

TB (M. tuberculosis)

Question 28

3 classes of exotoxins:

Answer 28

Class I- membrane acting/bind to host cell surface Class II- membrane damaging Class III- intracellular

Question 29

Pertussis toxin

Answer 29

ADP ribosylates G proteins-- blocks inhibition of adenylate cyclase in susceptible cells.

Question 30

Coagulase

Answer 30

converts fibrin to fibrinogen | Seen in S. aureus

Question 31

Advantages of biofilm formation

Answer 31

1- Resistance to antimicrobial agents 2- Resist host immune response 3- Act as reservoir

Question 32

Strategies for Fe acquisition by bacteria

Answer 32

1- Synthesis of surface receptors 2- Synthesis of siderophores 3- Reduction of Fe3+

Question 33

Streptokinase

Answer 33

"invasins" | converts plasminogen to plasmin protease--> allows spread of infection by breaking down fibrin barrier.

Question 34

Exs of emerging infectious disease:

Answer 34

Chikungunya | WNV

Question 35

Exs of re-emerging infectious diseases

Answer 35

Measles | M. tuberculosis

Question 36

Emerging diseases

Answer 36

- New/Never seen before - old diseases occurring in a new place and/or a new population - old diseases with new clinical presentations - old disease that has become newly resistant to medications

Question 37

CHIKV emergence

Answer 37

2013 emerged in the Caribbean Outbreaks of fever and debilitating arthralgia Autochthonous transmission

Question 38

WNV outbreaks

Answer 38

1999- NE USA (NY, NJ, DE, MD) 2000- PA,VA, NC 2001- Midwest, and SE 2002- CA, rocky mountain states, TX

Question 39

WNV emergence

Answer 39

widespread, multiple vectors (>30 different mosquitoes) Birds are reservoir Humans and Horses= dead-end hosts, who lack immunity. Can infect >150 diff spp. of birds No specificity of spp.

Question 40

Re-emergence

Answer 40

Previously present and increasing again in incidence. Due to: - susceptible population - changes in pathogen Seen in vaccine-preventable diseases

Question 41

Factors influencing disease emergence/re-emergence

Answer 41

``` 1- Human demographics and behavior 2- Technology and industry 3- Economic development and land use 4- International travel and commerce 5- Microbial adaptation and change 6- Breakdown of public health infrastructure. ```

Question 42

Ex of an emerging disease due to urbanisation

Answer 42

Dengue

Question 43

Dengue

Answer 43

Flaviviridae +ssRNA, icosahedral Enveloped Vector-borne daytime Aedes mosquito