Definition & Overview

Countless organisms, such as bacteria, parasites, viruses, or fungi thrive in the body. While the body doesn't pay much attention to some of them, some can cause diseases that can affect greatly on a person's health. In some cases, they are not satisfied with their host; they'll infect another host given the opportunity. These are called infectious diseases.

There are quite a number of infectious diseases and they infect millions of people worldwide. A great example is Salmonella, which is a foodborne bacteria and infectious disease. According to the Center for Disease Control, there were 53,800 new Salmonella cases in 2012 alone.

Some of the most common infectious diseases are tuberculosis, malaria, and AIDS. These diseases cause over 5 million deaths every year. Deaths due to infectious diseases are mostly caused by lack of treatment or when people with an infectious disease fail to seek treatment for the condition until it's too late.

With the right treatment, most infectious diseases can be cured. A good example is tuberculosis. In the past, no cure for this disease was available. However, when a cure was discovered, millions of lives around the globe were saved, especially when prompt treatment was provided.

Nowadays, it's easy to be infected with any type of disease because they can spread in a variety of ways. Some diseases are airborne, while others spread through body fluids. Below are the most common ways diseases are transferred from one person to another.

  • Air
  • Direct contact with an infected person
  • Through the skin
  • Through saliva
  • Through urine
  • Sexual contact
  • Contaminated food and water
  • Blood and other secretions

When you should see a Doctor

A person with an infectious disease will normally display symptoms. Most diseases have similar symptoms, especially when they had just begun. However, when the disease progresses, the symptoms can get more serious and cause life-threatening conditions.

The general symptoms of infectious diseases are fever, body ache, fatigue, and diarrhea. These will progress unless treatment has been provided. Therefore, it's imperative that you seek medical treatment as soon as you notice the symptoms or if you experience any of the following:

  • Coughs lasting more than a week
  • Rash or swelling
  • Sudden eyesight problems
  • Unexplained fever or prolonged fever
  • Breathing difficulties
  • Severe headaches
  • An animal bite

The doctor will diagnose your condition and determine the exact type of infectious disease. Some diseases can be treated at home using antibiotics and other medications, but some will need to be treated in a hospital setting. Isolations are sometimes needed to prevent the disease from spreading to the community. If you feel sick or believe that you have a disease, consult your doctor immediately. You have no way of knowing what type of disease you've been infected with, and you're risking the health and lives of your loved ones until you do.


  • Center for Disease Control
  • World Health Organization
  • Government of South Australia, SA Health
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