Paramedic Recert EMS Care | 23-MCIT-F3-4117 | Infectious Diseases starts with the introduction to the topic.

This chapter discusses infectious diseases, factors affecting the lifecycle of an infectious agent, pathophysiology, stages and antimicrobial resistance. The lessons also cover septic shock, sepsis and emerging and prevailing infectious diseases.

The lessons covered

• Lesson 1: What are Infectious Diseases?
• Lesson 2: Influenza.
• Lesson 3: Septic Shock and Sepsis.
• Lesson 4: Emerging and Prevailing Infectious Diseases.
• Lesson 5: Handling Infectious Diseases.

Excerpt from Paramedic Recert EMS Care | 23-MCIT-F3-4117 | Infectious Diseases

There are four specific stages from exposure to an infectious agent to the onset of clinical disease: the latent period, the incubation period, the communicability period, and the disease period. The duration of each stage and the potential outcomes vary depending on the infectious agent and individual host factors.

1. The latent period begins when the pathogen invades the body. During this period, infection has occurred, but the host is not contagious, unable to shed the pathogenic agent, and remains asymptomatic. The latent period as a stage of infectious disease differs from latent infection. Latent infections are characterized by periods of inactivity between attacks. Symptoms disappear during this stage but may reappear if the latent infection is reactivated.
2. The incubation period is the interval between exposure to the pathogen and the first onset of symptoms. Incubation periods can range from a few hours to 15 years or longer, just like the latent period. During incubation, the infectious organism reproduces in the host, and the immune system produces antibodies specific to the disease or antigen. Thus, a person’s blood may test positive (seroconversion) for exposure to the disease. Infection, however, is followed by a window phase. There is no detectable antibody during this phase, but the antigen is present. When testing for disease-specific antibodies during the window phase, a person may test negative even if they are infected.
3. The communicability period follows the latent period. The infection lasts as long as the agent is present and can spread to other hosts. This stage is variable and may occur during the incubation and/or disease periods. It often determines how easily a disease can spread. Depending on the disease stage and the primary site of infection, some diseases have a different communicability period and transmission method.
4. The disease period follows the incubation period. Depending on the disease, the duration may vary. There may be no symptoms during this stage, or there may be overt symptoms. They can be caused directly by the invading organism or by the body’s response to the infection. The body may sometimes be able to rid itself of the disease entirely during the disease period. In other cases, the organism may become incorporated inside certain cells and become inactive. Therefore, resolving symptoms does not necessarily mean the infectious agent has been eliminated.