Communicable Disease and Public Health

Communicable diseases are contagious illnesses caused by infectious, or pathogenic, agents. As a public health nurse, you'll prevent and control communicable diseases.

Now, the ability of a communicable disease to spread and cause infection depends on the interaction between three main factors that form the epidemiological triangle. These factors include an infectious agent, which can be any disease-causing microorganism including bacteria, viruses, fungi, or parasites; a host, or any person or animal harboring the infectious agent; and the environment, which are the external factors that influence disease transmission, like sanitation, crowding, or the presence of disease-transmitting insects like ticks.

The epidemiological triangle provides a foundation for understanding the sequence of events involved in the spread of infectious disease that are outlined in the chain of transmission. The first link in the chain is an infectious agent, which lives and multiplies in its reservoir. The reservoir can be another human, an animal, water, food, or contaminated surfaces. The pathway by which the infectious agent leaves the reservoir is the portal of exit, like bodily fluids or open wounds.

After that, the mode of transmission is how the pathogen travels from the reservoir to a new host. This can involve direct transmission, such as through sexual intercourse, skin to skin contact, or respiratory droplets; or indirect transmission, like touching a contaminated object, such as a door handle. Next, the infectious agent needs a portal of entry, which is the pathway by which it enters a new host, like through the mouth, nose, eyes, mucous membranes, or breaks in the skin.

Lastly, the susceptible host is anyone at risk for infection due to factors like age, health status, and immunity.

Alright, so, controlling communicable diseases is a key means of protecting and supporting public health. Control involves reducing the incidence, or new cases, and prevalence, or existing cases, of a communicable disease to a locally acceptable level; and continued efforts are required to maintain the reduction. For instance, the widespread use of vaccines can significantly control the number of new cases and deaths from vaccine-preventable diseases like measles and rubella within a community.

On the other hand, elimination is when a disease is controlled in a specific geographical area, like a country, so there are no new cases; though continued efforts are needed to prevent re-establishment of transmission. An example of this is when there are no new polio cases in a specific country, using an ongoing vaccination campaign.

If the disease is permanently eliminated, meaning the worldwide incidence of a disease has been reduced to zero and control measures are no longer needed, the disease has been eradicated. For instance, smallpox was eradicated in the 20th century, with the virus now only existing within laboratories.

As the public health nurse, you'll prevent and control communicable diseases by breaking the chain of transmission.