EXAM 3: Path & Epidem

Question 1

Infectious disease

Answer 1

A transmittable, clinically relevant, illness

Question 2

Morbidity

Answer 2

The state of being diseased or unhealthy, often times within a population

Question 3

Mortality

Answer 3

Death, often times within a population

Question 4

Pathogenesis

Answer 4

The process of disease development

Question 4

Pathogen

Answer 4

A microorganism that can cause disease

Question 5

Symptoms

Answer 5

Subjective characteristics of disease felt only by the patient

Question 6

Syndrome

Answer 6

A group of symptoms that consistently occur together or a condition characterized by a set of associated symptoms

Question 7

Signs

Answer 7

Objective manifestations of disease observed or measured by others

Question 8

Epidemiology

Answer 8

The branch of medicine that deals with the incidence, distribution, and control of diseases

Question 9

Incidence

Answer 9

Number of new cases of a disease in a given area during a given period of time

Question 10

Prevalence

Answer 10

Number of total cases of a disease in a given area during a given period of time

Question 11

Endemic

Answer 11

An illness that is prevalent in or peculiar to a particular region, or people

Question 12

Sporadic Disease

Answer 12

An illness that occurs at irregular intervals; having no pattern or order in time

Question 13

Outbreak

Answer 13

A sudden and unexpected increased disease incidence over the expected number of cases

Question 14

Epidemic

Answer 14

An outbreak of disease that spreads rapidly and widely within a contiguous geographic area

Question 15

Pandemic

Answer 15

An outbreak of disease that spreads rapidly and widely

Question 16

List and describe the three types of microbial symbiotic relationships

Answer 16

draw out chart

Mutualism: relationship where both involved benefit (Bacteria in human colon)

Commensalism: relationship where one organism benefits and the other is unaffected (staphylococcus on skin)

Parasitism: Relationship that benefits one and harms the other (tuberculosis bacteria in human lung)

Question 17

Discuss normal microbiota. Where are they found? What benefits can they provide?

Answer 17

• 10^14 prokaryotic cells and only 10^13 is eukaryotic
• Organisms that colonize the body’s surfaces without normally causing disease
• Can be commensal, mutualistic, or pathogenic

Resident Microbiota
* Are part of normal microbiota throughout life
* Are mostly commensal

Transient Microbiota
* Found in some regions as resident microbiota
* Remain in the body for short period of time
* Cannot persist in the body
Competition from other microorganisms
Elimination by the body’s defense cells
Chemical or physical changes in the body

Acquisition of normal microbiota:
The womb is an axenic (free of microorganisms)
Microbiota begin to develop during birthing process
Much of one’s resident microbiota established during first months of life

Benefits:
Assist in various bodily functions (digestion in large intestine)
Can protect from pathogens that enter the body
Drug metabolism
Maintains structural integrity of gut
Immunomodulation

Question 18

Differentiate between pathogens, opportunistic pathogens and non-pathogens

Answer 18

Opportunistic Pathogens:
Normal microbiota that cause disease under certain circumstances
- Introduction of normal microbiota into unusual site in body
- Immune suppression
- Immunocompromised
- Changes in the normal microbiota
——-> Changes in relative abundance may allow opportunity for a member to thrive and cause disease
——-> Broad spectrum antibiotics

Non-pathogenic:
Organisms that do not cause disease

Pathogenic:
Microorganisms that can cause disease in virtually any host

Question 19

Describe how microorganisms enter and exit the human host. What are the portals of entry and exit? How is infection transmitted to new host?

Answer 19

Four groups of transmission
1. Airborne Transmission
- Small particles that travel >1 meter
- Usually propelled from respiratory tract
2. Contact Transmission (direct contact or droplet)
- Large particles that travel <1 meter
- Coming together or touching of source/reservoir and host
3. Vehicle transmission (indirect contact/ water-borne/body fluid)
- Inanimate materials involved in pathogen transmission: Water, food and fomites
4. Vector-Borne transmission (biological host/mechanical)
- external and internal transmission

Portals of entry:
1. Skin
- pathogens can enter through openings or cuts
2. Mucous membranes
- Respiratory tract is the most common site of entry
3. Placenta
- Pathogens may cross the placenta and infect the fetus
4. Parenteral
- Pathogens deposited directly into tissues beneath the skin or mucous membranes. Ex: needlestick

Portals of exit:
- Ear (earwax)
- Eyes (tears)

Question 20

Discuss reservoirs of infection. List and describe the three types

Answer 20

Def: sites where pathogens are maintained as a source of infection

1. Animal reservoir
   - Zoonoses (learning objective in itself so know this)
   - Diseases naturally spread from animal host to humans
   - EX: rabies

• Acquire zoonoses through various routes
  
  • Direct contact with animal or its waste
  • Eating animals
  • Bloodsucking arthropods

2. Human carriers
   - Infected individuals who are asymptomatic but infective to others
   - Some individuals eventually develop illness while others never get sick
   - Healthy carriers may be protected by their immune system
3. Nonliving reservoir
   - Soil, water, and food can be reservoirs of infection
   - Presence of microorganisms often due to contamination by feces or urine

Question 21

Describe zoonoses

Answer 21

Zoonoses
Diseases naturally spread from animal host to humans
EX: rabies, lyme disease

Acquire zoonoses through various routes
- Direct contact with animal or its waste
- Eating animals
- Bloodsucking arthropods

Humans are usually dead-end host to zoonotic pathogens

Question 22

Explain the stages of disease

Answer 22

1. Incubation:
   Pathogen first enters body and begins to multiply
   NO signs or symptoms
2. Prodromal period
   General, non-specific signs and symptoms
3. Illness
   Infection specific and most severe signs and symptoms appear
4. Decline
   Immune system responds
   Declining signs and symptoms
5. Convalescence
   Pathogen is almost fully out of the body
   No signs or symptoms

Question 23

Compare and contrast the terms incidence and prevalence

Answer 23

Incidence
- Number of new cases of a disease in a given area during a given period of time

Prevalence
- Number of total cases of a disease in a given area during a given period of time

• They both refer to ways we track and measure the occurrence of diseases

Question 24

Explain the role of international and government agencies in disease control and prevention

Answer 24

Monitor incidence and occurrence
Response: public education
Agencies at the local, state, national, and global level share information concerning disease

Dept. of HHS is Cabinet level department
PHS is the primary division of HHS
Fed agencies under HHS & PHS: CDC, FDA, NIH

Question 25

Compare and contrast endemic, epidemic and pandemic.

Answer 25

They are similar in the way that they all refer to the ways in which disease affects a group of humans.

Endemic
An illness that is prevalent in or peculiar to a particular locality region, or people

Epidemic
An outbreak of disease that spreads rapidly and widely within a contiguous geographic area

Pandemic
An outbreak of disease that spreads rapidly and widely

Question 26

Define nosocomial infection and discuss contributing factors

Answer 26

• Hospital/healthcare acquired infection
• Any disease or illness that results from treatment in a hospital or healthcare setting
  —-> Precautions designed to reduce factors that result in disease
• 2 million infections per year in US (99,000 deaths)
• Antibiotic resistance a growing concern
• Hand washing is the best way to reduce nosocomial infections.
• Fomites and not handwashing can contribute

3 types of nosocomial infections:
Exogenous, Endogenous and Iatrogenic