Human Microbe Interactions

1. What is the difference between a sign and a symptom of disease?

Answer:

• Signs are objective and measurable

• Symptoms are subjective and experienced by the patient

Explanation:
Signs can be observed by clinicians (e.g., fever), while symptoms are felt (e.g., pain, fatigue)

2. A group of consistent signs and symptoms characteristic of a disease is called a:
A. Pathology
B. Syndrome
C. Etiology
D. Reservoir

Answer: B
Explanation:
A syndrome refers to a recognizable pattern of signs and symptoms

3. Define an asymptomatic (subclinical) infection.

Answer: An infection with no noticeable signs or symptoms.
Explanation:
Individuals may still transmit disease even without symptoms

4. Which disease type is short-term and follows a predictable pattern?
A. Chronic
B. Latent
C. Acute
D. Opportunistic

Answer: C
Explanation:
Acute diseases develop rapidly and last a short time (days–weeks)

5. Which type of disease remains dormant and can reactivate later?

Answer: Latent disease
Explanation:
Latent infections persist without active replication and may reactivate during stress or immunosuppression

6. What occurs during the incubation period?

Answer: Pathogen enters the body and begins multiplying; no symptoms yet.
Explanation:
This is the first stage of acute disease

7. Which factors affect the length of the incubation period? (Select all)

A. Strength of pathogen
B. Host immune defenses
C. Site of infection
D. Size of dose received
E. Blood type

Answer: A, B, C, D
Explanation:
All listed except blood type influence incubation length

8. During which period are symptoms mild and nonspecific?

Answer: Prodromal period
Explanation:
Pathogens continue multiplying and early symptoms appear

9. When are signs and symptoms most severe?

Answer: Period of illness
Explanation:
Pathogen load and symptom severity peak here

10. What happens during the period of decline?

Answer: Number of pathogen particles decreases.
Explanation:
Immune system begins controlling infection

11. Define the period of convalescence.

Answer: Recovery period when normal function returns.
Explanation:
Patient regains strength; pathogen numbers are low

12. Epidemiology is best defined as:

Answer: The study of when and where diseases occur and how they are transmitted.
Explanation:
Epidemiology focuses on disease patterns and prevention

13. What is morbidity?

Answer: Number of people affected by a disease.
Explanation:
Does not account for population size unless expressed as a rate

14. What does prevalence measure?

Answer: Total number of existing cases at a given time.
Explanation:
Includes both new and existing cases

15. Incidence refers to:

Answer: Number of new cases in a given time period.
Explanation:
Used to track disease spread

16. Which term describes deaths due to a disease?

A. Morbidity
B. Prevalence
C. Incidence
D. Mortality

Answer: D
Explanation:
Mortality rate measures disease-related deaths

Answer: D
Explanation:
Mortality rate measures disease-related deaths

Answer: Sporadic
Explanation:
Example: human rabies

18. A disease constantly present in a population is:

Answer: Endemic
Explanation:
Example: malaria in certain regions

19. A sudden increase in cases beyond expected levels is called:

Answer: Epidemic
Explanation:
Example: Ebola outbreak

20. A worldwide epidemic is a:Answer: Pandemic

Answer: Pandemic
Explanation:
Example: COVID-19

21. What is an etiologic agent?

Answer: The pathogen that causes a disease.
Explanation:
Etiology studies disease causes

22. Why must Koch’s postulates demonstrate causation rather than correlation?

Answer: To prove a microbe actually causes disease.
Explanation:
Presence alone does not prove causality

23. Which Koch postulate requires isolation of the pathogen?

Answer: The agent must be grown in pure culture from a diseased host.
Explanation:
This confirms the microbe can exist independently

24. List TWO limitations of Koch’s postulates.

Answer:

• Some pathogens cannot be cultured

• Ethical issues with human-only pathogens

Explanation:
Postulates cannot be applied universally

25. What is a reservoir of infection?

Answer: The natural habitat where a pathogen lives and multiplies.
Explanation:
Includes human, animal, and nonliving reservoirs

26. Which are the THREE reservoirs of infection?

Answer:

1. Human

2. Animal

3. Nonliving (soil, water)

Explanation:
Pathogens persist in these environments

27. Define a carrier.

Answer: An individual who can transmit a pathogen with or without symptoms.
Explanation:
Carriers play a major role in disease spread

28. Which type of carrier was Mary Mallon (Typhoid Mary)?

Answer: Asymptomatic carrier
Explanation:
She showed no symptoms but infected others

29. A disease transmitted from animals to humans is called:

Answer: Zoonosis
Explanation:
Examples include rabies and plague

30. Transmission via touching or sexual contact is:

Answer: Direct contact transmission
Explanation:
Person-to-person spread

31. What is the difference between droplet and airborne transmission?

Answer:

• Droplet: short distances

• Airborne: remains suspended longer

Explanation:
Airborne pathogens travel farther

32. What is the difference between biological and mechanical vectors?

Answer:

• Biological: vector is infected

• Mechanical: vector is not infected

Explanation:
Mosquito vs housefly example

33. What is the difference between horizontal and vertical transmission?

Answer:

• Horizontal: person to person

• Vertical: parent to offspring

Explanation:
Vertical includes pregnancy, birth, breastfeeding

34. Why is quarantining important?

Answer: Prevents disease spread during incubation.
Explanation:
Used for highly contagious diseases