Lec 01 Overview and Epidemiology of Infectious Diseases

Question 1

How is IDS epidemiology different from epidemiology in general?

Answer 1

• a case can also be an exposure to other patients
• subclinical infections influence epidemiology because they affect transmission
• contact patterns play a major role
• immunity plays a role
• there can be urgent and emergent situations at different levels

Question 2

Infectious diseases, as a whole, is the leading cause of mortality worldwide. (T/F)

Answer 2

T

Question 3

What demographics are disproportionately affected by infectious diseases?

Answer 3

young, elderly, people from low-income countries

Question 4

What is the rank of the country in terms of TB prevalence?

Answer 4

8

Question 5

What conditions facilitate the spread of infectious diseases?

Answer 5

• globalization of food supply
• overuse of antibiotics
• growth of mega-cities
• increasing proximity to disease vectors
• climate change
• transborder spread of diseases

Question 6

How are infectious diseases classified?

Answer 6

• established infectious diseases
• newly emerging infectious diseases
• reemerging infectious diseases

Question 7

What is colonization?

Answer 7

• presence of organism in the tissues without clinical and subclinical infection
• no signs and symptoms and no inflammatory response but the organism can replicate and organisms can be recovered by culture

Question 8

What is a carrier?

Answer 8

• individual colonized with organisms but shows no evidence of disease
• able to transmit the organism

Question 9

What are the components of the infectious disease triad?

Answer 9

host, agent, environment

Question 10

What conditions are necessary for an agent to be considered epidemiologically important?

Answer 10

• can be transmitted through the environment
• causes infection
• produces clinical disease

Question 11

What is infectiousness?

Answer 11

relative ease by which an agent is transmitted to other hosts

Question 12

What are the determinants of infectiousness?

Answer 12

• characteristics of the portals of entry and exit
• agent’s ability to survive away from the host
• ability to infect nonhuman hosts

Question 13

How do you compute for the Reproductive Number?

Answer 13

P x C x D
P - probability of transmission per contact
C - contacts per unit
D - duration of infectiousness

Question 14

What is infectivity?

Answer 14

• capability of the agent to enter, survive, and multiply in the host
• measured by the secondary attack rate

Question 15

How do you compute for the secondary attack rate?

Answer 15

number of infected/number of susceptible and exposed

Question 16

What is pathogenicity?

Answer 16

• extent to which overt disease is produced in an infected population
• number of patients with clinical disease/total number of infected

Question 17

What are the patterns of disease occurrence?

Answer 17

sporadic, endemic, hyperendemic, epidemic, pandemic

Question 18

What are the three main modes of transmission?

Answer 18

point-source outbreak, person-to-person outbreak, continuous-source outbreak

Question 19

What are the characteristics of the epidemic curve of a point-source outbreak?

Answer 19

abrupt onset and gradual descent with a single peak