Epidemiology

Question 1

What is Epidemiology?

The study of the [], distribution, and [] of health and [] in a population…

Answer 1

• occurence
• determinantts
• disease

Question 2

What is prevalence vs incidence?

Answer 2

• Prevalence - of a disease is the total number of new and existing cases in a population in a given time
  
  • Total number of people with a disease
  • Can be expressed as percentage
• Incidence - of a disease is the number of new cases of the disease in a given period of time.

Question 3

Are mobidity and Prevalence basically the same?

Answer 3

Yes

Question 4

Morbidity…

• Is a [] condition
• [] - [] are the presence of two or more diseased [] within an individual
• Morbidity also used to describe the [] of a disease in a population

Answer 4

1. diseased
2. Co-morbidities, states
3. rate

Question 5

Mortality…

1. measure of [] within a population due to any number of causes

Answer 5

• deaths
• not the same at morbidity.

Question 6

Using the examples of the common cold and ebola - differntiate morbidity and mortality….

Answer 6

• Morbidity and Mortality do not go hand in hand.
• Common Cold - high morbidity but low mortality
• Ebola - low morbidity but high mortality

Question 7

What is a diseases “progression” through stages in its host?

Answer 7

1. Infection - organism invades host
2. Incubation - no symptoms yet.
3. Prodromal - mild symptoms
4. Acute Phase - most sever signs and symptoms
5. Decline - disease and symptoms are subsiding
6. Convalescent Period - patent regains strength and returns to normal.

Question 8

Which disease stage experience the most sever symptoms?

Prodromal or Period of decline?

Answer 8

• Pysche!
• Neither should - the acute phase experiences the most sever signs and symptoms

Question 9

In which disease stage is the disease most likely gone from the host?

Decline or Convalescent

Answer 9

Convalescent

Question 10

An Acute Infection can be a [] force. How?

Answer 10

• Selective Force
• As a population we do not have a good immune response/response yet…since it is the first time we experience it. So it is most likely to be deadly.

Question 11

Do organisms that cause chronic infections lose or gain virulence?

Answer 11

• It depends.
• Most pathogens that are well adapted will become less and less virulent over time
  
  • Chlamydia for example - doesnt really kill peeps.
• There are some exceptions though.

Question 12

Since the parasite/virus/bacteria most likely needs the host to survive…[]-[] of host and parasite is common.

Answer 12

Co-evolution

Question 13

A disease is [] if it is not usually presnt in a population and occurs infrequently

Answer 13

sporadic

Question 14

An [] disease is constantly present in a populaiton, usually at low incidences.

Answer 14

endemic

Question 15

A disease [] occurs when a number of cases of a disease are reported in a short period of time.

Answer 15

outbreak

Question 16

A disease is an [] when it occurs in a large number of people in a population at the same time (usually spread out but still geographically contained)

Answer 16

epidemic

Question 17

A disease [] is widespread, usually worldwide.

Answer 17

pandemic

Question 18

Which disease transmission mechanism occurs in a small time frame and arrises from contamination of water or food?

Answer 18

• Common-source epidemics
• Cholera

Question 19

What is the R₀ number?

Answer 19

• The basic reproduction number
  
  • number of cases predicted to arise from one single infected individual.
  • Can only be gathered once disease is contained and well-tracked.

Question 20

Which type of disease transmission mechanism shows a slow progressive rise and a gradual decline over a longer time frame?

Answer 20

• Host-to-Host epidemic
• Influenza and chicken pox

Question 21

1. Resistance of a group to infection due to immunity of a high proportion of the group = []?
2. The [] [] number is the number of people in a population that need to be vaccinated in order to prevent the spread of a disease?

Answer 21

1. Herd Immunity
2. Herd Immunity Number

Question 22

Diseases with high R_o numbers can be [] ?

A high R_o normally correlates to a [] Herd Immunity number?

Answer 22

1. Cyclical
2. Higher

Question 23

1. A [] host-to-host transmission - the infected individual transmits a disease directly to a susceptible host
2. Without the assistance of an []

Answer 23

1. Direct
2. Intermediary
3. Examples:
   
   1. Viral Flu, common cold, STD, ringworm

Question 24

Transmission of a disease facilitated by an intermediary is a ….

Answer 24

Indirect host-to-host transmission.

Question 25

What is a disease reservoir? What are some examples of reservoirs?

Answer 25

* site in which infectious agent remain viable and from which infection of individuals can occur. * Ex: * Zoonosis - pathogens can be transmitted to humans from animals * Vectorborne agents use insects/invertebrates as reservoirs * Human carrier * Anthrax can use soils (non-living reservoir) * Giardia live in water (non-living reservoir)

Question 26

What are 2 examples of non-living reservoirs?

Answer 26

* Giardia in water * Anthrax in soils

Question 27

What is a subclincal infection? What are people called who have a subclinical infection?

Answer 27

1. Diseased individuals who show nor or mild symptoms. 2. Carrier

Question 28

What are 3 methods of control against a host?

Answer 28

1. **Surveillance** - observation, recognition, and reporting of disease 2. **Quarantine** - restricts movement of individual with active infection 3. **Travel Restrictions** - lime likelihood through geographic isolation

Question 29

What are controls directed against the "vehicle?

Answer 29

* Preventing contamination through water treatment and purification, proper sanitation procedures, food preparation guidelines * "decontamination of wastes"

Question 30

What are some controls against a "reservoir?"

Answer 30

* If reservoir is animal - immunize or destroy * Insect habitats can be sprayed with insecticides

Question 31

What controls can be directs against the pathogen?

Answer 31

* Immunization through vaccines * Treatment through antivirals, antibiotics * Less effective cuz spread not prevented

Question 32

What is the difference between an emergent and re-emergent disease?

Answer 32

* Emergent - disease that suddenyl becomes prevalent * Re-emergent - diseases that have become prevalent after having been under control

Question 33

What are the 7 "common" ways a disease emerges in a population?

Answer 33

1. Human demographics and behavior changing 2. Technology and Industry 3. Economic development and land use 4. International travel and commmerce 5. Pathogen adaption 6. Breakdown of public health 7. Unusual events that upset host-pathogen balance

Question 34

What characteristics should a biological agent possess?

Answer 34

1. High transmission rate 2. high mortality 3. very stable, low rates of immunity 4.

Question 35

What are the 3 ways anthrax can infect someone? Which way is the most lethal?

Answer 35

1. Cutaneous - non lethal 2. Gastrointestinal - rare 3. Pulmonary - deadly