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Viral Infections

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Viral Infections

7 min read


There are a number of notable viral infections that are among the most common afflictions of humans. Read this article to know about common viral infections and to perceive the common ways to combat them.

Medically reviewed by

Dr. N. Ashok Viswanath

Published At January 7, 2022
Reviewed AtMarch 2, 2023


There are millions of viruses that exist, but scientists have identified about 5000 types till date. Viruses are smaller than bacteria. The person with the virus may seem to have fully recovered, but they may fall sick once the virus reactivates. It was found that children experience two to seven respiratory infections every year. For most viral infections, treatments help only with the symptoms while you wait for the immune system to fight off the virus. Recently there has been a dramatic progression in antiviral therapeutics. Vaccines have helped in the prevention of many viral diseases.

What Is a Virus?

Viruses are tiny organisms that are made up of genetic material, DNA (deoxyribonucleic acid), or RNA (ribonucleic acid) surrounded by a protein coat, and this genetic material contains the information needed to make copies of the virus. Viruses cause some common illnesses such as cold, flu, and warts, and similarly, they are also responsible for causing severe illnesses such as HIV and AIDS (acquired immunodeficiency syndrome), Ebola, and COVID-19 (coronavirus disease 2019). These viruses invade the normal living cells, multiply and produce other viruses like themselves. They can also kill, damage, or change the cells and make the person fall sick. Whenever a virus gets into the individual's body, it is not always necessary for the person to fall sick as their body's immune system will be able to combat it off.

Viruses are classified into two depending on which they used to replicate:

There are some viruses that cause chronic infections, such as hepatitis B and hepatitis C virus.

How Do Viruses Spread?

Viruses are transmitted in various ways. They can be swallowed or inhaled. They can also be spread through the bites of infected insects, which include mosquitoes, certain biting flies (deer flies, horse flies, sand flies and snipe flies) and ticks. There are chances for the viruses to spread sexually and during transfusion of the contaminated blood. Recently human viruses developed from viruses that affect animals emerged. This happens when the infected animal comes in close contact with susceptible humans.

What Are the Multiple Types of Viral Infections?

Viral infections are infections caused due to proliferation of a harmful virus inside the body. Viruses usually affect only one particular type of cell. Depending on the type of cell the virus affects, it is classified into different types. Some of the different types of viral infections include:

  • Respiratory tract viral infections.

  • Viral infections of the gastrointestinal tract.

  • Viral skin infections.

  • Viral infections of the liver.

  • Viruses that affect the nervous system.

  • Sexually transmitted infections.

Respiratory Tract Viral Infections:

Respiratory viral infections typically affect the nose, lungs, and airways. These viruses are spread through inhalation of the air droplets containing the virus particles. The typical respiratory infections are upper respiratory tract infections. Some of the upper respiratory tract infections include:

  • Common Cold:

The common cold is the most common viral infection of the upper respiratory tract. It is a contagious viral infection. There are many different respiratory viruses that can cause common colds. Among all, rhinoviruses are the most common. The viruses often spread through airborne droplets that are coughed or sneezed into the air by the infected person. Adults have about 2 to 3 colds every year, and children have even more. The symptoms of the common cold include:

  • Sore throat.

  • Runny nose.

  • Sneezing.

  • Coughing.

  • Headaches.

  • Nasal congestion.

Normally, people recover within 7 to 10 days.

Other viral respiratory infections include:

  • Seasonal Influenza:

Seasonal influenza is an acute respiratory illness caused by the influenza virus. There are four different influenza viruses. Seasonal influenza is manifested by sudden onset of fever, dry cough, headache, sore throat, runny nose, muscle, and joint pain. Seasonal influenza spreads easily with rapid transmission in crowded places such as schools, dormitories, and nursing homes. When the infected person coughs or sneezes, the virus-containing droplets can spread to one meter and can infect the people who are in close proximity.

  • Pneumonia:

Pneumonia refers to the inflammation of the air sacs in one or both lungs. There are a variety of organisms that can cause pneumonia, including viruses, bacteria, and fungi. Some of the viruses that cause the common cold and flu can also cause pneumonia. The viruses are the most common cause of pneumonia in children who are below five years. Some of the symptoms of pneumonia include a cough that can produce phlegm, fatigue, fever, chest pain while breathing, and shortness of breath.

Preventive Measures:

  • Avoid being in close contact with the person who is sick.

  • Stay isolated if you are sick.

  • One needs to cover their nose and mouth while coughing or sneezing.

  • Wash your hands after sneezing.

  • Wipe the commonly touched objects such as remote controls, doorknobs, lift switches, and light switches if it has been touched by the people in the house who have the viral infection.

Viral Infections of the Gastrointestinal Tract:

Certain viruses cause food poisoning. Food-borne viral infections are transmitted via the fecal-oral route. This means the virus particles enter the body when the person ingests the virus particles that were shed through the feces of the infected person. Contaminated water can also be responsible for the spread of the infection.

  • Viral Gastroenteritis:

Viral gastroenteritis refers to the inflammation of the intestines caused by viruses. It is characterized by watery diarrhea, abdominal pain, nausea, and vomiting. It is often known as stomach flu. The most common viruses that are responsible for the infection include noroviruses and rotaviruses. The person gets infected with this virus by ingesting contaminated food or water.

Ways to prevent viral infections of the gastrointestinal tract:

  • Wash your hands thoroughly before handling food items.

  • Avoid eating uncooked or undercooked foods.

  • Wash the fruits and vegetables before cooking.

  • Do not share your utensils if you are ill.

Viral Skin Infections:

Viral skin infections are transmitted through sharing things such as towels, utensils with the infected person using communal swimming pools. Some of the common viral skin infections include:

  • Molluscum Contagiosum:

Molluscum contagiosum is a viral skin infection. It is characterized by small bumps that are flesh-colored in children of ages 1 to 10 years. However, it can affect people of any age. These bumps usually disappear after six to twelve months without any treatment.

  • Herpes Simplex Virus:

Herpes simplex virus is a serious contagious virus that causes an infection called herpes. This viral infection gets transmitted from person to person through direct contacts, such as eating in the same utensils, sharing lip balms, and kissing. Herpes can occur in any part of the body. However, it is commonly seen on the genitals and mouth. In some instances, people do not show any symptoms of still having an infection. But if they show symptoms, then some of the commonly reported symptoms include:

  • Mouth sores or sores in the genital area.

  • Itching.

  • Pain while urinating.

  • Varicella-Zoster Infection:

Varicella-zoster virus is a DNA virus that causes chickenpox and shingles. The primary infection caused by the varicella-zoster virus causes varicella (chickenpox). Chickenpox is also characterized by a fever followed by rashes. When the varicella-zoster virus stays in the body after the primary infection, it is known as latent infection. This reactivation of the latent infection causes shingles.

Viral Infections of the Nervous System:

The common viral infections of the nervous system include:

  • Viral Meningitis:

Meningitis refers to the inflammation of the membranes surrounding the brain and spinal cord. When meningitis is caused by a virus, it is referred to as viral meningitis. In most cases, people get better without any treatment. However, meningitis can be a serious condition, so you need to see the doctor right away when you start noticing the signs and symptoms of meningitis such as lethargy, photophobia (sensitivity to light), nausea, vomiting, irritability, stiff neck, fever, headache, excessive sleepiness, and appetite loss. Non-polio enteroviruses, mumps virus, Epstein-Barr, herpes simplex viruses are the common viruses that can cause meningitis.

  • Viral Encephalitis:

Encephalitis means inflammation of the brain. There are many causes for encephalitis, but among them, viruses are the common cause. Viral encephalitis has similar symptoms like flu-symptoms such as:

  • Fever.

  • Headache.

  • Fatigue.

  • Confusions.

  • Seizures.

  • Muscle weakness.

  • Problems with speech or hearing.

Viral Infections of the Liver:

Hepatitis is the common viral infection of the liver. Some hepatitis viruses can cause chronic infections, and these chronic infections can last for years. In most people, chronic hepatitis is mild and causes little liver damage, whereas, in some people, it eventually results in cirrhosis (scarring of the liver) and liver failure.

Sexually Transmitted Infections:

The viral infections can also be transmitted sexually by having sexual intercourse with the person with a sexually transmitted infection or through close contact with bodily fluids such as blood. Here are a few sexually transmitted viral infections:

  • Human Papillomavirus (HPV) Infection:

Human papillomavirus infection is a serious viral infection that causes skin growths called warts. Some HPV infections cause warts, whereas a few can lead to cancer. Some types of genital HPV can cause cervical cancer. These viral infections are often transmitted sexually or through skin-to-skin contact.

  • Genital Herpes:

Genital herpes is a sexually transmitted infection. There are two types of herpes simplex virus. Herpes simplex virus-2 usually causes genital herpes. These viruses enter the body through skin abrasions or mucous membranes and cause herpetic sores (fluid-filled blisters) in the genitals.

  • Human Immunodeficiency Virus (HIV):

The human immunodeficiency virus is typically an infectious virus that can affect the body's own immune system. It destroys the CD4 cells, weakening the individual's immunity against opportunistic infections like tuberculosis and fungal infections. This virus spreads through unprotected sex with the infected person, by sharing needles, or through contact with bodily fluids like blood. The viruses can also be transmitted from mother to baby during pregnancy, childbirth, or breastfeeding.

Preventive Measures:

  • Practice safe sex.

  • Use condoms as it can lower the risk though it does not completely eradicate the possibility of getting a sexually transmitted infection.

  • Minimize the number of sexual partners.

How Are Viral Infections Treated?

In most viral infections, treatment helps alleviate the symptoms while you wait for the immune system to fight off the virus. Antibiotics do not help with viral infections as only bacterial infections respond to antibiotics. There are certain antiviral medicines to treat some viral infections. Even vaccines can also help prevent getting viral illnesses.


Take infections seriously. Follow the precautionary measures to stay safe. And if you are ill, then stay home so that you do not transmit the infection to others.

Frequently Asked Questions


How Long Will It Take for Symptoms of Viral Infections to Subside?

Depending upon the type of virus involved, the duration of viral infections will vary. Usually, the symptoms of viral infections can last from three to four days to two weeks. It will also depend upon the individual's immune system. If the immunity is high, the symptoms will not be that prominent.


What Are the Five Most Common Viral Infections?

Viral infections are those diseases caused by common microorganisms known as viruses. They are many types of viruses responsible for causing infections. The most common viral infection that humans encounter is the common cold. The seasonal flu caused by influenza, bronchitis, gastroenteritis, herpes, chickenpox, and some ear infections are the other common viral infections.


What Is the Best Way to Get Rid of Viral Infections?

Mild viral infections do not require any specific treatment. Supportive measures like taking proper rest, steam inhalation, staying hydrated, over-the-counter drugs, etc., can help reduce the severity of symptoms. If the symptoms are severe, then antivirals may be required. In the cases where the temperature is not decreasing, headache, abdominal pain, difficulty breathing, etc., in such cases, should consult a doctor.


How to Treat Viral Infections at Home?

Viral infections are generally not serious. With proper care, most of them can be treated at home. Staying hydrated, steam inhalation, keeping the body temperature cool by giving a sponge bath in lukewarm water, over-the-counter drugs, and taking proper rest can relieve the symptoms. But if the symptoms are getting worse, you should see a doctor immediately.


What Is the Treatment for Viral Eye Infection?

Eye infections due to the viruses can be highly contagious. The most common viral eye infection is conjunctivitis. There is no specific treatment for viral eye infections. Most of them can be treated at home. Applying cold compress, artificial tears, or topical antihistamines can give symptomatic relief. Antiviral drugs are recommended in some cases.


How to Distinguish Between Bacterial and Viral Eye Infections?

Both bacterial and viral eye infections are highly contagious. It can spread easily through the direct or indirect contact of the discharge from the affected eyes. Bacterial eye infections are usually accompanied by pus discharge, whereas a clear or white discharge usually indicates viral infections. The eyes will be redder in color in bacterial eye infections.


Which Are the Most Prominent Viral Infections That Affect the Skin?

Skin infections due to viruses can be mild to severe. The lesions on the skin can be a symptom of viral infection in the body, or it can be an actual infection of the skin. Most of the viral infections of the skin require medical help. The most prominent viral infections on the skin are herpes simplex, shingles, molluscum contagiosum, and viral warts.


How to Identify a Viral Rash?

The rashes due to viruses can be a manifestation of viral disease in the body or a virus attack directly on the skin. It can be itchy or painful. The duration and appearance of these rashes can vary. But in most cases, they appear as red or pink spots on the skin.


Can We Use Antibiotics for Viral Infections?

No, antibiotics cannot be used for viral infections. Antibiotics have a different mechanism of action and are used primarily for bacterial infections. Antivirals can be used in the case of viral infections.


Can Viruses Attack Blood Cells?

Yes, viruses can attack blood cells. When the viruses enter the bloodstream, the condition is known as viremia. It can enter the human body through sexual contact, blood transmission from an affected individual, the bite of an infected insect, through an open wound, and breastmilk.


How Long Can a Viral Infection Spread From an Affected Individual to a Healthy Person?

The infectious period of viral infections can vary. The viral infection can be contagious two or three days before the symptoms appear in most cases. The infectious period can last upto one or two weeks after the symptoms appear in the case of measles, shingles, etc.
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Dr. N. Ashok Viswanath
Dr. N. Ashok Viswanath

Infectious Diseases


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