Education, Infectious Diseases

A Guide to Viral Infections

Author Kimberly Hazel , 10-May-2022

Viral infections are a common and often serious threat to our health and well-being; they are known as infectious diseases. In this guide, we will explore what viral infections are, the different types of viruses that can infect the body, their symptoms, how they are diagnosed and treated, as well as ways to prevent the spread of viral infections.

A Look at Viruses


There are many different types of viruses that can affect humans. A virus is a microscopic agent that can only replicate inside the cells of another organism. Viruses are not considered alive, but they do have some characteristics of life, such as the ability to mutate and evolve.

Most viruses are very small and can only be seen with a microscope. They are typically round or bullet-shaped and range in size from about 20 to 300 nanometers in diameter.

Viruses are very simple, and their genomes consist of either DNA or RNA but never both. They do not have the ability to metabolize on their own and must hijack the cellular machinery of their hosts in order to create new viruses.

Most viruses are harmless to humans, but a few can cause serious diseases such as AIDS, Ebola, and Influenza.

What is a Viral Infection?


Viral infections are generally mild and self-limiting, but some can be severe or even deadly. Several factors contribute to the severity of a viral infection, including the type of virus involved, the individual’s age and health status, and whether or not the person has previously been infected with that particular virus.

Some viruses, such as the flu virus, can cause severe respiratory illness. Other viruses, such as the common cold virus, usually cause milder diseases. Some viruses, such as the human immunodeficiency virus (HIV), can cause lifelong infection and eventually lead to death.

There are many different types of viruses, and they can infect almost any kind of living thing, including plants, animals, and humans.

Virus Types


  • gastrointestinal viral diseases: infections that cause inflammation of the stomach and intestines. These diseases can be caused by various viruses, including rotaviruses, adenoviruses, astroviruses, coronaviruses, and picornaviruses. Symptoms of gastrointestinal viral diseases include diarrhea, vomiting, abdominal pain, fever, and blood in the stool.
  • hemorrhagic viral diseases:  These diseases are caused by viruses that specifically attack the body’s blood vessels. This can lead to internal bleeding and hemorrhaging from the eyes, nose, or gums. Patients can experience organ failure due to massive blood loss in severe cases. There is no specific cure for these diseases; treatment typically consists of supportive care such as fluids and electrolyte replacement.
  • respiratory viral diseases: A type of infection that affects the lungs and airways. The most common respiratory viral diseases are influenza (the flu) and the common cold. These viruses can cause mild to severe respiratory illness and, in some cases, can lead to death.
  • cutaneous viral diseases: a type of infection that affects the skin. There are many different types of cutaneous viral diseases. These infections can cause various symptoms, including blisters, sores, itching, and discomfort.
  • neurologic viral diseases:  There are a few different types of viral diseases that can impact the nervous system. Treatment for these types of infections often includes antiviral medications. In some cases, surgical intervention may be required to relieve pressure on the brain or spinal cord.


The Most Common Viruses


Some viruses are more common than others. The most common viral infections in the world include:

All of these viruses are highly contagious and can cause serious illness.

The Rarest Viruses


There are several rare viral infections that can occur in people all over the world. Some of these infections are more common in certain parts of the world than others, while others are quite rare no matter where you live. Here are some of the rarest viral infections in the world:


Each of these viruses has a very low incidence rate and can be deadly if not treated immediately.

In addition to these viruses, many other rarer infections have recently been discovered. These include the novel coronavirus (MERS-CoV), which caused an outbreak in Saudi Arabia in 2012; the Zika virus, which is responsible for a recent outbreak in South America; and the Powassan virus, which is transmitted by ticks and can cause encephalitis.

Symptoms of Viral Infections


The symptoms of viral infections can vary depending on the type of virus causing the infection but can include:

  • fever
  • chills
  • body aches
  • fatigue
  • nausea and vomiting
  • diarrhea
  • coughing and difficulty breathing


In some cases, viral infections can also lead to more severe complications like pneumonia or meningitis.

Diagnosing a Virus


Doctors typically diagnose viral infections based on the symptoms a patient is experiencing. In some cases, they may order lab tests to confirm the diagnosis.

Treatment for These Infections


There is no specific cure for viral infections, but there are treatments available to help ease symptoms and speed up recovery. In most cases, viral infections will go away on their own within a few days or weeks. However, some viruses can cause lifelong infections or lead to serious health complications.


What is an Antiviral, and How Does it Work?


An antiviral is a type of medication used to treat infections by viruses. Antivirals work by targeting and inhibitors specific aspects of the virus’ life cycle, which differs depending on the type of virus.

There are several different types of antivirals, including nucleoside analogs, protease inhibitors, entry inhibitors, and interferon-based drugs.

For example, some antivirals are designed to prevent the replication of the virus (interferon-based drugs). In contrast, others may work to block attachment or entry of the virus into cells (entry inhibitors). In general, antivirals are most effective when started within 48 hours of the onset of symptoms.

Modes of Transmission: How Viruses are Spread and Why They are Infectious


There are a few different ways that viruses can spread. These are known as modes of transmission. These modes include contact, airborne, droplet, vectors, and vehicular (contaminated inanimate objects such as food, water, and fomites).

Contact Spread or Surface Spread


Transmission of viruses occurs when an infected person transmits the virus to another via direct touch. This might occur, for example, through handshaking, using utensils, or even touching something contaminated with viral particles. When someone comes into close contact with germs on a surface, they may inadvertently spread those viruses to their hands. The virus can then enter their body through their eyes, nose, or mouth if they touch their face.

Indirect contact is another transmission mode. Touching a doorknob, for example, after touching the hand of someone who has the virus is an example of this. Viruses can survive for a surprisingly long time on surfaces.


Airborne Spread


Viruses may be spread both by contact and in the air. When a person coughs or sneezes, viruses can get out into the air. These airborne infections might then be breathed in by other people, causing them to become sick.

This happens because some viruses are carried on air currents in droplet nuclei, which is commonly known as an airborne or aerosol spread. Many types of viral infections can be spread through the air.


Droplet Spread


Droplet spread, on the other hand, is one of the most common methods by which viruses replicate and cause sickness. Because an infected droplet is released from the mouth or nose and lands on a surface, this form of transmission is special. The virus may then easily infect anyone who makes direct contact with the surface. Many respiratory illnesses have been caused by this technique of propagation.

Because these are heavier nuclei, they are not classified as aerosols or airborne transmission modes. Some researchers feel that droplet spread is comparable to contact spread, while others believe it is a separate mode of transmission.


Vector Spread


The transfer of a virus from one host to another is known as vector spread. There are several ways this might happen, but most experts believe that mosquito bites are the main mechanism for transmission. This generally happens when an arthropod (mosquito, tick, louse) feeds on an infected person and passes germs on to another uninfected individual.

Mosquito-borne viruses are one of the most common causes of disease, accounting for a significant percentage of the world’s illnesses. Some examples of mosquito-borne viruses are dengue fever and Zika virus.


Vehicular Spread: Food or Water Contamination


The spread of viral particles from one location to another via a vehicle is known as vehicle-based transmission. Food, water, and fomites are the most common vehicles for viral dispersion.

Viruses can be spread through food and water in a variety of ways. The most typical method of transmission is by contaminated food and water that has not been cooked or washed properly. An inanimate thing that can store and transmit germs is called a fomite. Hands, skin, and other objects are examples of common fomites in this process of infection.

Preventing the Spread of Viral Infections


There are a few things you can do to help prevent the spread of viral infections, including washing your hands regularly, avoiding close contact with people who are sick, and getting vaccinated against viruses like influenza. If you think you may have a viral infection, it is important to see a doctor so that you can get the proper treatment and avoid any potential complications.

Kimberly Hazel

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