Components of Infectious Diseases

Question 1

Pathogen

Answer 1

• Disease-causing microorganisms (e.g., bacteria, viruses, fungi, parasites).

Question 2

Reservoir

Answer 2

• Natural habitat of the pathogen (humans, animals, environment).

Question 3

Portal of Entry

Answer 3

• Routes pathogens enter the host: respiratory tract, GI tract, genitourinary tract, skin breaks.

Question 4

Susceptible Host

Answer 4

• Vulnerable individuals due to age, immune status, genetics, or health conditions.

Question 5

Transmission

Answer 5

• The process by which the pathogen is transferred from the reservoir or infected host to a susceptible host
• Modes: direct contact, indirect contact, airborne, vector-borne, food/waterborne.

Question 6

Colonization

Answer 6

• Pathogen establishes and multiplies in the host.

Question 7

Invasion

Answer 7

• Pathogen spreads from initial site to other tissues/organs.

Question 8

Multiplication

Answer 8

• Pathogen replicates, increasing load and causing damage.

Question 9

Host Response

Answer 9

• Immune system activates to eliminate the pathogen (antibodies, immune cells).

Question 10

Disease Manifestation

Answer 10

• Clinical symptoms (mild to severe) based on pathogen virulence and host factors.

Question 11

Chain of Infection

Answer 11

Infectious Agent
Reservoir
Portal of Exit
Mode of Transmission
Portal of Entry
Susceptible Host

Question 12

Infectious Agent

Answer 12

• Pathogen capable of causing disease.

Question 12

Portal of Exit

Answer 12

• Route pathogen leaves the reservoir (e.g., respiratory secretions, feces).

Question 12

Mode of Transmission

Answer 12

• Direct/indirect contact, airborne, vector-borne, food/waterborne.

Question 13

Reservoir

Answer 13

• Source where the pathogen lives and multiplies.

Question 14

Susceptible Host

Answer 14

• Vulnerable individual lacking immunity.

Question 15

Portal of Entry

Answer 15

• Route pathogen enters the host.

Question 16

Prevention

Answer 16

• Break any link (vaccination, hygiene, sanitation).

Question 17

Infectious Disease Spectrum

Answer 17

Asymptomatic Infection
Subclinical Infection
Mild/Moderate Illness
Severe Illness
Chronic Infection
Latent Infection
Fatal Outcome

Question 18

Subclinical Infection

Answer 18

Individual experience mild or Non-specific symptoms that may go unnoticed or be attributed to other causes

Question 19

Asymptomatic Infection

Answer 19

Individuals infected with pathogen but show no noticeable symptoms. They can still transmit infection to others

Question 20

Mild/Moderate Illness

Answer 20

Symptoms vary depending on the pathogen involved but may include; fever, cough, sore throat, fatigue, muscle aches gastrointestinal symptoms and respiratory symptoms

Question 21

Severe Illness

Answer 21

Some infectious disease can cause severe illness that requires hospitalization and may lead to death e.g sepsis, ARDS(acute respiratory distress syndrome)

Question 22

Fatal Outcome

Answer 22

Infectious diseases can be severe and cause death. Severity and fatal outcome of disease vary depending on the pathoge host factors

Question 22

Latent Infection

Answer 22

Infection remains dormant in the body for an extended period without causing symptoms. Later activates and leads to recurrent episodes of illness e.g herpes simplex virus

Question 23

Chronic Infection

Answer 23

Chronic infection can persist over an extended period, sometimes for a person's lifetime e.g Hepatitis B, HIV Hepatitis C