1 - The Global Impact of Infectious Diseases

Question 1

What are parasites?

Answer 1

protozoa and worms

Question 2

What is parasitism?

Answer 2

a relationship between 2 species in which one species benefits and the other species is harmed

Question 3

mutualistic

Answer 3

both organisms benefit

Question 4

commensal

Answer 4

A relationship between two organisms in which one organism benefits and the other is unaffected

Question 5

what is the 1st stage of infectious disease?

Answer 5

Incubation period

Question 6

what is the 2nd stage of infectious disease?

Answer 6

prodomal period

Question 7

what is the 3rd stage of infectious disease?

Answer 7

illness

Question 8

what is the 4th stage of infectious disease?

Answer 8

convalescence

Question 9

what is the incubation period?

Answer 9

time between infection and the occurrence of first symptoms or signs of disease

Question 10

What is the prodromal period?

Answer 10

short time of generalised, mild symptoms (such as fatigue)

- not all infectious diseases have this stage

Question 11

what is the illness stage?

Answer 11

most severe stage when symptoms are most evident and host immune system not yet fully responded

Question 12

What is the convalescent period?

Answer 12

body gradually returns to normal (variable time depending on pathogen and damage)

Question 13

what does the clinical picture depend on?

Answer 13

• infecting dose
• age of host
• gender of host
• host genetics
• host nutritional status
• co-infection with other pathogens
• type of infectious agent

Question 14

what are the stages of disease progression?

Answer 14

invasion, multiplication, spread, pathogenesis

Question 15

What is invasion?

Answer 15

involves entry into the host and transmission from one host to another

Question 16

what are the 7 ports of invasion?

Answer 16

inhalation, oral transmission, intra-uterine, sexual transmission, direct skin contact, direct inoculation, insect bites

Question 17

examples of inhalation invasion

Answer 17

Influenza (virus)
SARS-CoV-2 (virus)
Yersinia pestis (bacterium)

Question 18

examples of invasion via oral transmission

Answer 18

Ascaris (nematode)
Taenia solium (cestode)

Question 19

examples of invasion via intra uterine

Answer 19

Toxoplasma (protist)

Question 20

examples of invasion via sexual transmission

Answer 20

HIV (virus)

Question 21

examples of invasion via direct skin contact

Answer 21

Hookworms (nematode)

Schistosomes (trematode)

Question 22

example of invasion via direct innoculation

Answer 22

HIV (virus)

Question 23

examples of invasion via insect bite

vector borne

Answer 23

Plasmodium (protist)
Yersinia pestis (bacterium)
Wuchereria bancrofti (nematode

Question 24

what does the route of transmission do?

Answer 24

influences disease control measures

Question 25

protist multiplication

Answer 25

can multiply within the body - disease severity may depend on how quickly they multiply

Question 26

helminth multiplication

Answer 26

most helminths cannot multiply within the body and so disease severity is dependent upon the number of infectious stages acquired by host over time

Question 27

what is spread?

Answer 27

ability of the organism to move from the initial site of infection to infect other areas of the body

Question 28

what is pathogenesis?

Answer 28

causation and development of clinical disease

Question 29

which 3 factors is pathogenesis influenced by?

Answer 29

1. The number of pathogenic organisms present
2. The virulence of the organism
3. The reaction of the host - degree of resistance (immunity?)

Question 30

how do we measure burden of disease?

Answer 30

incidence, prevalence, mortality

Question 31

what is incidence?

Answer 31

number of new cases of infection occurring in a population in a defined period of time

Question 32

What is prevalence?

Answer 32

total number of infected individuals in a population at a given point in time

Question 33

what is mortality?

Answer 33

total number of deaths from disease in a population in a defined period of time

Question 34

what is the disability adjusted life year

Answer 34

Measures ‘life years’ lost due to premature mortality and equivalent years lost because of morbidity

Question 35

how do you calculate 1 daly?

Answer 35

‘years of life lost (YLL) to premature mortality’ + ‘years lost to (lived with) disability (YLD)’

Question 36

Limitations of DALY

Answer 36

• only measure direct health loss
• do not consider economic impact from disease
• do not account for direct treatment cost
• do not consider social stigma