In this video, we're going to differentiate between communicable diseases and noncommunicable diseases. Some diseases can actually easily spread from one person to another, while other diseases cannot spread from one person to another. Communicable diseases, which are also sometimes referred to as contagious diseases or infectious diseases, are diseases that can spread between hosts. These communicable, contagious, or infectious diseases are diseases that can easily spread from one person to another. Now, the term "infectious dose" refers to the specific number of microbes that are required to establish an infection in a host. A pathogen that has a very high infectious dose will only cause disease if the person is exposed to a very high number of microbes. Whereas a pathogen with a very low infectious dose can cause disease even if a person is only exposed to a very small number of microbes. We'll be able to get a better understanding of communicable, contagious, or infectious diseases as well as the infectious dose down below on the left-hand side of our image when we get there.
Noncommunicable diseases, on the other hand, are noninfectious diseases that do not spread from host to host. They do not spread between hosts or from one person to another. An example of a noncommunicable disease would be cancer, which is not communicable. It is a noncommunicable disease because cancer does not spread from one person to another. These noncommunicable diseases can arise from genetic, physiological, lifestyle, and environmental factors, and they're not typically the result of a pathogen. Communicable, contagious, or infectious diseases, on the other hand, typically result from pathogens or disease-causing agents.
We will take a look at the left-hand side of our image over here to get a better understanding of communicable diseases. Recall that these diseases can spread from one person to another. Notice we have an unhealthy person showing signs and symptoms and a healthy person. That infected person seems to be coughing and sneezing, spreading microbes. If this microbe has a very high infectious dose, then it takes a lot of microbes to make you sick. If this person is only exposed to a low number of microbes, then that would not be enough microbes to make this person sick, and so they would remain healthy. However, if this person is exposed to a high number of microbes, when the microbe has a high infectious dose, then that would be enough to make them sick. Notice here that they have a thermometer in their mouth and they're not feeling very well.
On the right-hand side, we're showing a noncommunicable disease that does not spread from one person to another. Notice that this person over here is smoking tobacco, which contains all types of carcinogens and mutagens, things that cause cancer and mutations. This person loves smoking, but smoking can lead to cancer. Cancer is an example of a disease that is noncommunicable because it does not spread from one person to another.
This here concludes our brief lesson on communicable versus noncommunicable diseases, and we'll be able to get some practice applying these concepts as we move forward in our course. I'll see you all in our next video.