Transmission of Infection and Infection Control

Question 1

What is the term for living or nonliving material in which infectious agents multiple and develop and depend on for survival?

Answer 1

Reservoir

ex. human (influenza virus)
ex. animal (rabies virus)
ex. inanimate (Clostridium tetani–> spores in soil)

Question 2

What is the incubation period?

Answer 2

Time from entry of pathogen to first appearance of signs/symptoms of disease.

ex. influenza: 1-3d
ex. common cold virus: 12h-5d
ex. chickenpox (VZV): 2-3 wks

Question 3

What is the period of communicability?

Answer 3

Time during which pathogen is capable of being transmitted/

ex. influenza virus: clinical onset to 3-5d post onset
ex. common cold virus: 24h before onset to 5d after onset
ex. VZV (chickenpox): 1-2d before onset of rash until all lesions crusted (5d)

Question 4

What are examples of infectious agents transferred by direct contact?

Answer 4

• HIV (mucous membrane to mucous membrane)
• Herpes virus (muc to muc)
• impetigo due to streptococcus pyogenes (skin to skin)

Question 5

What are examples of infectious agents transferred via indirect contact?

Answer 5

ex. antibiotic resistant organisms: clostridium difficile, respiratory viruses (via hands, fomites)
ex. norovirus, rotavirus, salmonella spp., shigella spp., campylobacter spp., e.coli (fecal-oral)
- HIV, Hepatitis B, Hepatitis C (needlestick)

Question 6

What size are ‘droplets’ and how far can they be propelled in the air?

Answer 6

> =5um

2 m distance

Question 7

What are examples of droplet-transmitted infectious agents?

Answer 7

• respiratory viruses: respiratory syncytial virus, influenza, parainfluenza, adenovirus, rhinovirus
• neisseria meningitidis

Question 8

What are examples of airborne infectious agents?

Answer 8

• mycobacterium tuberculosis
• measles
• varicella zoster virus (chickenpox)

Question 9

What are examples of vector-borne infectious agents?

Answer 9

• West Nile Virus
• Malaria

(via mosquitoes)

Question 10

What is a ‘common vehicle’ of transmission? Give examples.

Answer 10

common vehicle= a single contaminated source that transmits infection to multiple hosts

ex. food, medication, IV fluid, equipment

examples from news: Walkerton drinking water (E coli), EEG electrodes (Hep B), Acupuncture needles (Mycobacterium abscessus)

Question 11

What are the 6 main arms of ‘public health measures’ to prevent spread of infectious disease?

Answer 11

1. Vaccination
2. Post-exposure prophylaxis
3. Reportable Disease
4. Contact Tracing
5. Quarantine
6. Outbreak investigation

Question 12

What infections do we vaccinate against in Canada?

Answer 12

• Diphtheria
• Pertussis
• Tetanus
• Polio
• Haemophilus B (Hib)
• Pneumococcal
• Rotovirus
• Meningococcal
• Measles
• Mumps
• Rubella
• Chickenpox (Varicella)
• Hepatitis B
• HPV
• Influenza

Question 13

What are 7 examples of vaccinations given to travelers (dependent on destination)?

Answer 13

• Hepatitis A
• Yellow fever
• Typhoid
• Cholera
• Neisseria meningitidis
• Japanese encephalitis
• Rabies

Question 14

List infections that have vaccines and/or immunoglobulins for prophylaxis post-exposure:

Answer 14

1. Hep B (vaccine, Ig)
2. Hep A (vaccine, Ig)
3. Varicella Zoster (vaccine, Ig)
4. Rabies (vaccine, Ig)
5. Measles (vaccine, Ig)
6. Botulism (Ig)

Question 15

List infections that have post-exposure prophylaxis in the form of antimicrobials/antivirals

Answer 15

1. Pertussis
2. Invasive Neisseria meningitidis
3. Invasive Streptococcus pyogenes
4. HIV

Question 16

According to the ‘Health Protection and Promotion Act’, which individuals/bodies must report suspected occurrences/occurrences of reportable diseases to the local Health Unit?

Answer 16

• physicians
• laboratories
• admins of hospitals
• schools

Question 17

What is the term for the tracking of all individuals who have been exposed to a person with a communicable disease during its period of communicability?

Answer 17

‘Contact Tracing’

Question 18

What antibiotic resistant organisms are surveilled for nosocomial infx?

What other organisms can cause hospital-acquired infx?

Answer 18

• Methicillin-resistant Staphylococcus aureus (MRSA)
• Vancomycin-resistant enterococci (VRE)
• Extended-spectrum beta-lactamase producing GN (ESBL)
• Carbapenemase-producing GN (KPC, NDM-1)
• Clostridium difficile and Influenza virus also cause HAI

Question 19

What are two means of decolonizing a host from antibiotic resistant organisms like MRSA?

Answer 19

1. topical or systemic antibiotics

2. photodisinfection

Question 20

Give examples of prophylactic post-exposure treatments for:

1. Invasive Neisseria meningitidis
2. Invasive Streptococcus pyogenes
3. Needlestick injuries

Answer 20

1. Neisseria m. : Rifampin or ciprofloxacin
2. Strep p. : Penicillin+rifampin or clindamycin or azithromycin
3. Needlestick:
   - Antiretroviral rx
   - Hep B vaccine/Ig
   - Monitoring HIV, Hep B, Hep C seroconversion

Question 21

What are the 7 steps of an outbreak investigation?

Answer 21

1. confirm outbreak exists
2. develop a case definition
3. create line listing and epicurve
4. assemble team
5. institute control measures
6. evaluate efficacy of control measures
7. declare outbreak over

Question 22

What are 3 types of outbreaks?

Answer 22

1. point source (one bad meal at old age home)
2. common source (sick chef works for 5 days)
3. propagated spread (person to person spread)