Question: Which of the following is the first link in the chain of infection?
A Susceptible Host
B Mode of Transmission
C Infectious Agent
D Reservoir
Answer: Infectious Agent
| Link in the Chain of Infection | Description | |
| 1.
| Infectious Agent | · The pathogen causing the infection e.g., bacteria, viruses, fungi, parasites. · Characteristics of pathogen include virulence, resistance and the ability to survive and multiply. |
| 2.
| Reservoir | · The source or host where the infectious agent resides and reproduces. · Can be human, animal, or environmental (e.g., contaminated water or soil). · Reservoirs may be symptomatic or asymptomatic carriers. |
| 3.
| Portal of Exit | · The pathway through which the infectious agent leaves the reservoir. · For examples respiratory secretions, blood, urine, feces and open wounds. |
| 4.
| Mode of Transmission | · The method by which the infectious agent is transferred from reservoir to a susceptible host. · Modes include direct contact and indirect through contaminated objects. |
| 5.
| Portal of Entry | · The route through which the infectious agent enters a susceptible host. · Includes mucous membranes, respiratory, gastrointestinal and genitourinary tracts. |
| 6.
| Susceptible Host | · The individual who is at risk of becoming infected. · Factors affecting susceptibility include age, immunity, overall health and genetics. · The presence of other illnesses can increase susceptibility. |