Host Microbe Interaction

Question 1

Clinical Infection

Answer 1

Infections with signs and symptoms

Question 2

Sub-clinical Infection

Answer 2

Infection with pathogen but no symptoms

Question 3

Iatrogenic Infection

Answer 3

From a medical practitioner / intervention (hospital)

Question 4

How are respiratory infections transmitted?

Answer 4

• Droplets (cough-sneeze)
• Saliva
• Soil-dust
• water aerosols

Question 5

Zoonoses is a term used for what kind of disease?

Answer 5

Diseases transmitted by vectors (insects and animals)

Question 6

Endemic

Answer 6

Disease present in a community (region) all the time,

usually only clinical in a few

Question 7

Epidemic

Answer 7

Wide spread disease within a community (region),

affecting many people but only occasionally present

Question 8

Pandemic

Answer 8

Wide spread epidemic, not confined to a single

community or region (more than one continent)

Question 9

Sporadic

Answer 9

Widely scattered disease, occurring singly,

irregularly, infrequently

Question 10

Epidemiology

Answer 10

The study of the spread, frequency, distribution of

disease

Question 11

Explain the difference between Morbidity and Mortality

Answer 11

Mortality: Number of deaths caused by infective agent
Morbidity: Number made ill by infective agent

Question 12

Explain the difference between Incidence and Prevalence

Answer 12

Incidence: Number of new cases over specific period
Prevalence: Number of cases (infected or diseased) at a given time (old and new cases)

Question 13

In epidemiological terms how would you classify the disease “AIDS”

Answer 13

AIDS is a pandemic; wide spread epidemic

Question 14

What factors influence the spread of disease in a community?

Answer 14

• Virulence of the pathogen
• Pathogen transmission mode
• Population susceptibility and immunity

Question 15

List four ways of preventing the spread of disease in a community

Answer 15

• Immunisation
• Prevent contamination of water supplies
• Isolate diseased persons
• Educate the public

Question 16

Which disease of the following disease type would most likely spread quickly through the Perth community and why? Gastroenteritis, STI, Respiratory disease

Answer 16

STI; HPV 53 was the most prevalent in a WA study, can be spread quickly and easily

Question 17

What are the two branches of the immune system?

Answer 17

Innate: Non specific defences which do not require
previous exposure to foreign agent
Adaptive: Response based on specific recognition of invader (foreign agent), consists of antibody mediated and cell mediated responses

Question 18

How does skin protect against bacteria?

Answer 18

• Contains normal flora to provide competition for pathogenic microbes that want to grow on the skin

Question 19

What white blood cells (WBC) types are phagocytic?

Answer 19

Neutrophils, monocytes and eosinophils

Question 20

What type of white blood cell (WBC) is mainly involved in the adaptive immune system?

Answer 20

Lymphocyte

Question 21

What antibody types are involved in the primary and secondary immune response?

Answer 21

Primary: IgM
Secondary: IgG

Question 22

What type of lymphocyte is involved in cell mediated immunity?

Answer 22

T-lymphocyte

Question 23

List the ways antibodies fight infection.

Answer 23

• Neutralise viruses and toxins
• Trigger phagocytosis
• Aggultination

Question 24

List the antibody isotypes

Answer 24

• IgG
• IgA
• IgM
• IgE
• IgD

Question 25

What are the 4 cardinal signs of inflammation and how do they come about?

Answer 25

• Redness (increased blood flow)
• Heat (increased blood flow)
• Swelling (lymphatic fluid)
• Pain (inflammatory substances released cause pain)

Question 26

Describe the difference between humoral and cell mediated immune responses.

Answer 26

Humoral: uses antibodies as main form of immune response

Cell-mediated: uses cytotoxic T-cells and natural killer cells as main form of immune response

Question 27

List and describe the types of T cells

Answer 27

• Cytotoxic T cells

- Natural killer cells

Question 28

What is the MHC and what is its purpose?

Answer 28

• Major Histocompatibility Complex
• purpose is to bind peptide fragments from pathogens and display them on the cell surface in order to recognised by the appropriate T–cell for destruction

Question 29

Describe the difference between passive and active vaccination

Answer 29

Passive:

• Rely on injected antibodies into the body against a particular antigen
• Often happens after an infection
• The recipient does not produce an immune response of their own
• Short term

Active:

• Rely on administering an antigen into the body so the body can produce its own antibodies
• Prophylaxis (prevents future infection)
• Recipient produces their own immune response and remembers antigen for secondary responses
• Long term

Question 30

How do autoimmune diseases occur?

Answer 30

• When the immune system attacks itself
• Example is type 1 diabetes mellitus
• Destruction of the β-cells of islets of langerhans in pancreas
• β-cells responsible for insulin production
• Cytotoxic T cells followed by auto-antibodies
• Anti-Islet cell antibodies (ICA)