Education, Infectious Diseases

What are Infectious Diseases?

Author Kimberly Hazel , 25-Apr-2022

Many people might think of specific illnesses such as the flu, measles, or Ebola. However, infectious diseases are much broader than that and include various illnesses caused by viruses, bacteria, fungi, and other parasites.


Some infections can be deadly, while others may only cause a minor illness. This blog post will explore the definition of infectious diseases, discuss where they come from, and look at some famous examples. We will also touch on how researchers are working to find new ways to prevent and treat these illnesses.


The five most common of these diseases in the United States are:

  1. Respiratory syncytial virus (RSV)
  2. Human metapneumovirus (hMPV)
  3. Influenza A virus
  4. Rhinovirus
  5. Adenovirus

The Four Main Types of Infectious Disease


Infectious diseases are caused by microorganisms, such as viruses, bacteria, fungi, or parasites, spreading from person to person. They can also be transmitted through exposed food or water, contact with animals, or contaminated surfaces. These diseases can be mild, such as the common cold, or more serious, such as pneumonia.

There are four main types:


Bacterial infectious diseases are caused by bacteria, single-celled microorganisms that can multiply quickly. They are often treated with antibiotics.

Viral infectious diseases are caused by viruses, tiny infectious particles that invade living cells and replicate inside them. Viruses are usually spread through coughing and sneezing or contact with contaminated surfaces. They can sometimes be treated with antiviral medicine.

Fungal infectious diseases are caused by fungi, multicellular organisms that can live on dead or decaying matter. Fungi can also cause infections in people with weakened immune systems. Treatment for these diseases usually involves antifungal medications.

Parasitic infectious diseases are caused by parasites, tiny organisms that live on or inside other organisms (hosts) and rely on them for food and shelter. Some parasites can cause severe illnesses in humans. Treatments for parasitic diseases vary depending on the type of parasite involved.

Common Diseases and Symptoms


The symptoms of an infectious disease depend on the type of microorganism causing the infection. They can range from mild to severe and may include fever, coughing, diarrhea, vomiting, and rash. In some cases, infections can be deadly.

There are many different infectious diseases, but some of the more well-known and contagious include:

  • Tuberculosis: a bacterial infection that usually affects the lungs but can spread to other parts of the body, such as the brain and spine. Symptoms include coughing up blood, weight loss, fatigue, and fever. Untreated tuberculosis can be fatal.
  • AIDS: a viral infection that attacks the immune system and leaves the body vulnerable to other infections and illnesses, which can be deadly. Symptoms include fever, fatigue, weight loss, and diarrhea. There is no cure for AIDS, but there are treatments available that can prolong a person’s life.
  • Malaria: a parasitic infection that is spread by mosquito bites. Symptoms include fever, chills, sweats, headaches, muscle aches, and nausea. Malaria can be fatal if not treated promptly.
  • Influenza: a viral infection that primarily affects the respiratory system. Symptoms include fever, sore throat, runny nose, muscle

Other well-known diseases include measles and chickenpox. Still, this is just the tip of the iceberg regarding infectious diseases. It’s difficult to estimate the number of infectious diseases worldwide because new pathogens are always emerging, and some existing pathogens are constantly changing. That being said, according to the World Health Organization, about 200 infectious diseases pose a public health concern.


Why Communicable Diseases are a Medical and Public Health Concern


According to the World Health Organization (WHO), infectious diseases are responsible for approximately one-third of deaths yearly.

There are several reasons why communicable diseases are a public health concern. First and foremost, communicable diseases have the potential to cause a great deal of harm to those who contract them. In some cases, communicable diseases can be deadly. Even when they are not deadly, communicable diseases can often cause serious illness and long-term health problems. That is why it is critical to treat infectious diseases promptly.

Additionally, communicable diseases can be transmitted from one person to another, meaning that they have the potential to cause outbreaks. When communicable diseases cause outbreaks, known as infectious disease outbreaks, the number of people who become sick can quickly increase, putting a strain on healthcare resources and the healthcare system. In fact, some diseases are of such concern they require notifying certain authorities and health entities. These are known as notifiable infectious diseases and are tracked through infectious disease surveillance.

Also, vaccine-preventable communicable diseases are a public health concern because they are preventable. When people do not vaccinate against communicable diseases, they put themselves and others at risk of becoming sick. In conclusion, communicable diseases are a significant public health concern because of the harm they can cause, their potential to cause outbreaks and their vaccine-preventability.


Preventing the Spread & Treating the Infection Early


Preventing the spread of infectious diseases is essential to protect yourself and others. Some simple tips to prevent the spread of infection and germs include:

  • Washing your hands often with soap and water or using an alcohol-based hand sanitizer
  • Avoiding close contact with people who are sick
  • Covering your mouth and nose when you sneeze or cough
  • Avoiding touching your eyes, nose, or mouth
  • Cleaning and disinfecting surfaces that are frequently touched
  • Getting vaccinated against infectious diseases that can be prevented


If you think you may have an infectious disease, it is crucial to see a healthcare provider. Early diagnosis and treatment can help prevent the disease from spreading and becoming more severe. Many tools diagnose infectious diseases, including physical exams, blood tests, x-rays, and MRIs.

Treatment for infectious diseases depends on the type of infection involved. Bacterial infections are usually treated with antibiotics, while viral infections cannot be cured but can often be treated symptomatically.


The Importance of Immunity


In some cases, infectious diseases can be prevented through vaccination. Vaccines work by protecting people against the microorganisms that cause infectious diseases.

Immunity is another essential tool in the fight against infectious diseases. Immunity occurs when the body produces antibodies to protect itself against a specific infection. Immunity can be acquired through vaccination or previous exposure to an infectious disease. People who have immunity to infection cannot get that infection again.


Kimberly Hazel

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