Chp 16 Epidemic

Question 1

What is epidemiology?

Answer 1

The study of where and when diseases occur and how they are transmitted within populations.

Question 2

What is etiology?

Answer 2

The study of the causes of diseases.

Question 3

What are the three types of reservoirs for infectious diseases?

Answer 3

1. Animal reservoir, 2. Human carriers, 3. Nonliving reservoir (soil, water, food).

Question 4

What are zoonoses?

Answer 4

Diseases that naturally spread from animal hosts to humans.

Question 5

What is a passive carrier?

Answer 5

A person who is not infected but can mechanically transmit pathogens to others (e.g., a healthcare worker who fails to wash hands).

Question 6

What is an active carrier?

Answer 6

An infected individual who transmits the disease to others, possibly without showing symptoms.

Question 7

What is an asymptomatic carrier?

Answer 7

An infected individual who does not show signs or symptoms of disease but can still transmit it (e.g., herpes simplex virus, HIV).

Question 8

What are the three groups of disease transmission?

Answer 8

1. Contact transmission, 2. Vehicle transmission, 3. Vector transmission.

Question 9

What is direct contact transmission?

Answer 9

Transmission that involves body contact between hosts, such as touching, kissing, or sexual contact.

Question 10

What is vertical direct transmission?

Answer 10

Pathogens transmitted from mother to child during pregnancy, birth, or breastfeeding.

Question 11

What is indirect contact transmission?

Answer 11

Pathogens spread via fomites (inanimate objects like doorknobs, needles, or drinking glasses).

Question 12

What is droplet transmission?

Answer 12

Spread of pathogens in droplets of mucus through coughing, sneezing, or exhaling (limited to less than 1 meter).

Question 13

What is vehicle transmission?

Answer 13

Spread of pathogens through air, water, food, or bodily fluids handled outside the body.

Question 14

What is airborne transmission?

Answer 14

When pathogens travel more than 1 meter via aerosols (e.g., through sneezing, coughing, or air-conditioning systems).

Question 15

What is waterborne transmission?

Answer 15

Spread of gastrointestinal diseases via fecal-oral route or contaminated water, often due to poor sanitation.

Question 16

What is the fecal-oral route of transmission?

Answer 16

Pathogens from feces contaminate food or water, which is then ingested by another person.

Question 17

What is a biological vector?

Answer 17

An arthropod (e.g., mosquito, tick) that transmits pathogens and serves as a host for some stage of the pathogen’s life cycle.

Question 18

What is a mechanical vector?

Answer 18

An animal (e.g., housefly) that passively carries pathogens on its body but is not a host for the pathogen.

Question 19

What is morbidity?

Answer 19

The state of being diseased, which can be expressed as the total number of cases or as a rate (e.g., per 100,000 people).

Question 20

What is mortality?

Answer 20

The number of deaths in a population, often expressed as a rate (e.g., deaths per 100,000 people).

Question 21

What is incidence?

Answer 21

The number of new cases of a disease in a given area during a specific period.

Question 22

What is prevalence?

Answer 22

The total number of cases of a disease in a given area during a specific period, including new and pre-existing cases.

Question 23

What is a sporadic disease?

Answer 23

A disease that occurs in scattered or isolated cases (e.g., a few cases of plague in the western US).

Question 24

What is an endemic disease?

Answer 24

A disease that is widespread within a certain area or population most of the time (e.g., malaria in Brazil).

Question 25

What is an epidemic?

Answer 25

A disease that is widespread within a certain area or population at a particular time (e.g., influenza in the US during some winters).

Question 26

What is a pandemic?

Answer 26

A disease that spreads over a whole country, continent, or the world (e.g., COVID-19).

Question 27

What is quarantining?

Answer 27

The isolation of individuals suspected or known to have been exposed to a contagious pathogen to prevent disease transmission.

Question 28

What is an exogenous infection?

Answer 28

A healthcare-associated infection where the pathogen comes from the healthcare environment.

Question 29

What is an endogenous infection?

Answer 29

A healthcare-associated infection where the pathogen arises from the patient’s own normal microbiota.

Question 30

What is an iatrogenic infection?

Answer 30

A healthcare-associated infection resulting from modern medical procedures.

Question 31

What is an opportunistic infection?

Answer 31

An infection that occurs when the use of antimicrobial drugs inhibits some resident microbiota, allowing other microbes to thrive.

Question 32

What is the most effective way to reduce healthcare-associated infections?

Answer 32

Handwashing.

Question 33

What is an emerging infectious disease?

Answer 33

An infection that has recently appeared within a population or whose incidence or geographic range is rapidly increasing.

Question 34

What are re-emerging infectious diseases? Give ex.

Answer 34

Diseases whose incidence had significantly declined in the past but have reappeared (e.g., tuberculosis).

Question 35

What are some risk factors for emerging infectious diseases?

Answer 35

Microbial adaptation, climate change, human demographics, poverty, war, and bioterrorism.

Question 36

What is the primary route of transmission for Chikungunya fever?

Answer 36

Mosquito-borne.

Question 37

What are the general steps in how a disease is transmitted?

Answer 37

1. Reservoir: where pathogen resides. 2. Portal of exit: pathogen leaves the reservoir through a portal of exit. 3. Mode of transmission: pathogen is transmitted via direct contact, indirect contact, airborne, or vector-borne routes. 4. Portal of entry: The pathogen enters a new host through a portal of entry. 5. Susceptible host: The new host must be susceptible to the pathogen for infection to occur.

Question 38

What are the three types of contact transmission?

Answer 38

1. Direct contact transmission (physical contact between an infected person 2. Indirect contact transmission (transmission via fomites). 3. Droplet transmission (spread of pathogens occurs in droplets of mucus).

Question 39

How does airborne transmission differ from droplet transmission?

Answer 39

Airborne transmission involves small particles (aerosols) that remain suspended in the air for long periods and can travel long distances (e.g., tuberculosis, measles). Droplet transmission involves larger respiratory droplets that travel short distances ( less than 1 meter) and quickly settle on surfaces (e.g., influenza, common cold).

Question 40

Besides air, what are the other three types of vehicle transmission?

Answer 40

1. Waterborne transmission (e.g., cholera). 2. Foodborne transmission (e.g., Salmonella). 3. Bodily fluids handled outside the body: Improper use of PPE can lead to exposure from infected fluids such as blood, urine, saliva, etc.

Question 41

What are the two types of vector transmission?

Answer 41

1. Biological vectors: Transmit pathogens and serve as hosts for some stage of the pathogen’s life cycle (e.g., mosquitoes, ticks). 2. Mechanical vectors: Animals that passively transmit pathogens present on their body to new hosts (e.g., houseflies).

Question 42

What are the types of carriers of infection?

Answer 42

1. Active carriers: Infected individuals that transmit the disease to others. 2. Passive carriers: Contaminated with the pathogen and can mechanically transmit it to another host. 3. Asymptomatic carriers: Active carriers who do not show signs or symptoms of disease despite being infected.

Question 43

How are carriers different from vectors?

Answer 43

Carriers are humans or animals that carry and transmit pathogens. Vectors are typically arthropods (e.g., mosquitoes, ticks) that transmit pathogens.

Question 44

Can carriers, vectors, or both cause zoonoses?

Answer 44

Both carriers (animal reservoirs) and vectors (biological vectors) can cause zoonoses.

Question 45

What are two ways incidence, prevalence, and mortality can be expressed?

Answer 45

1. As a total number of cases or deaths. 2. As a rate (e.g., per 100,000 people).

Question 46

What are nosocomial infections?

Answer 46

Infections acquired while receiving treatment in a healthcare facility.

Question 47

What are the four most common types of nosocomial infections?

Answer 47

1. Surgical infections. 2. Pneumonia. 3. Urinary tract infections (UTIs). 4. Bloodstream infections.

Question 48

How can nosocomial infections be controlled?

Answer 48

Hand hygiene, environmental hygiene, screening and cohorting patients, surveillance, antibiotic stewardship, following guidelines, and safety culture.

Question 49

How is an emerging infectious disease different from someone getting sick with the common cold?

Answer 49

Emerging infectious disease: An infection that has recently appeared within a population or whose incidence or geographic range is rapidly increasing (e.g., Ebola). Common cold: A well-known, endemic disease caused by common viruses and not considered emerging.

Question 50

What are two reasons why an infectious disease might emerge?

Answer 50

1. Microbial adaptation: Genetic drift and genetic shift in Influenza A. 2. Changing human susceptibility: Mass immunocompromisation with HIV/AIDS.