Summary of Study Session 1

In Study Session 1 you have learned that:

  1. Communicable diseases are caused by infectious agents that can be transmitted to susceptible individuals from an infected person, or from other animals, objects or the environment.
  2. Infectious agents include helminths, protozoa, bacteria, viruses and fungi.
  3. Six factors are involved in the transmission of communicable diseases: the infectious agent, the reservoir, route of exit, mode of transmission, route of entry, and the susceptible host.
  4. A reservoir is a human, another animal, or a non-living thing (such as soil), where the infectious agent normally lives.
  5. Modes of transmission of an infectious agent can be directly through person-to-person contact, or across the placenta from mother to fetus. Indirect transmission can occur through air, vehicles such as water, food and contaminated objects, or via a vector such as a mosquito.
  6. A susceptible host is a person or animal who can develop infection if exposed to the infectious agent. Susceptibility is increased if exposure is high, or the host’s immunity is low.
  7. The natural history of an untreated communicable disease has four stages: stage of exposure, stage of infection, stage of infectious disease, and stage of outcome.

1.3.4  Stage of outcome

Self-Assessment Questions (SAQs) for Study Session 1