Virus molecules in the human body.

A Viral Infection Overview: Respiratory, Neurologic and More

What Is a Viral Infection?

Although not all viruses are dangerous, some may cause infection and sickness. The degree of illness that a person will experience from a virus varies. Viral infections are often widespread and may affect people differently. Viruses are also different in their route of transmission and type of illness they cause.

But what is a viral infection? In this article we discuss what a virus is, different types of viral infections, types of transmission and treatment options.

What Is a Virus?

A virus particle contains genetic material surrounded by protein. Viruses do not reproduce on their own. To survive, a virus requires a host. The host can include a person, animal, or insect.

Viruses can affect different parts of the body, such as the respiratory, reproductive and gastrointestinal tract. The severity of a virus can vary greatly. In some cases, a virus can be life-threatening. In other instances, it may cause only mild symptoms. There are many types of viral infections that target certain organs.

Viral Respiratory Infections

Viral respiratory infections affect the throat, nose and lungs. Viral respiratory infections can be dangerous, especially to people with underlying lung issues, such as asthma or COPD.

There are many types of viruses that may cause a respiratory infection. The exact symptoms may vary depending on the virus, but in general, there are common symptoms of a viral respiratory infection:

  • Coughing
  • Runny nose
  • Sore throat
  • Shortness of breath
  • Wheezing
  • Fatigue
  • Fever


This is one of the most frequent causes of the common cold, but it is not the only one. According to the National Institutes of Health, there are about 200 viruses that cause the common cold. Although it can vary, cold symptoms usually last one to two weeks.


Viruses that cause the seasonal flu may vary each year. According to the American Lung Association, there are three main causes of the flu, including influenza A, influenza B and influenza C viruses.


Coronavirus is another viral respiratory infection. COVID-19 is a new strain of the virus. Researchers and doctors are still learning more about COVID-19, but according to the Centers for Disease Control and Prevention, it appears it is primarily spread via respiratory droplets.

Transmission of Viral Respiratory Infections

Viral respiratory infections are usually spread through contact with respiratory droplets. For example, if someone with an infection coughs, they may spread the virus through the droplets from their mouth. Viral infections are also transmitted through touching surfaces contaminated with droplets.

Who Is at Risk for Viral Respiratory Infections?

Anyone is at risk for a viral respiratory infection. In fact, most people develop an infection, such as the common cold, at some point in their life.

Infants, the elderly and those with underlying medical conditions or a compromised immune system are at the most risk of complications from a viral respiratory infection.

Treatment Options for Viral Respiratory Infections

Treatment for viral respiratory infections may vary depending on the virus. In some cases, treatment is supportive and aimed at reducing symptoms. Common treatments may be:

  • Nasal decongestants
  • Cough suppressants
  • Analgesics, such as acetaminophen, for fever reduction
  • Zinc to reduce symptom duration

Antiviral medications are also sometimes recommended to reduce the severity of an infection. Additionally, new treatments are in clinical trials for COVID-19.

Protecting Yourself from Viral Respiratory Infections

Although you may not always be able to prevent every viral respiratory infection, there are some things you can do:

  • Get a flu vaccine every year
  • Wash your hands frequently
  • Avoid touching your mouth, nose, and eyes
  • Avoid close contact with people that are sick
  • Maintain healthy lifestyle habits to strengthen your immune system, such as eating healthy, exercising regularly, and getting enough sleep

Viral Neurologic Infections

Viruses can also attack the tissues of the brain and cause neurological symptoms. Viral neurological infections are one of the most dangerous types of viral infections. In some cases, they are deadly.

Symptoms of a viral neurological infection:

  • Confusion
  • Sleepiness
  • Fever
  • Seizures
  • Fatigue
  • Headache

Viral Meningitis

Viral meningitis involves inflammation of the lining of the spinal cord and brain. Meningitis may also occur due to a bacterial infection. Viral meningitis tends to be less severe than bacterial, but it can still be dangerous.


Rabies is transmitted from animals to humans, usually through a bite from a rabid animal. According to the World Health Organization, dogs are the most common animal to cause rabies in humans.

Viral Encephalitis

Viral encephalitis is also an inflammation of the brain, which can occur due to a virus. Infections that cause viral encephalitis can be spread through a bite from an infected bug, such as a mosquito.

Transmission of Viral Neurologic Infections

Some viruses that cause neurologic infections are transmitted through respiratory droplets or by touching contaminated surfaces. Other routes of transmission involve a bite from an infected bug or animal.

Who Is at Risk for Viral Neurological Infections?

Anyone can develop a viral neurological infection, but some people may be at a higher risk. According to the CDC, people with a weakened immune system and those under age 5 are at a higher risk of viral meningitis. People that spend a lot of time outdoors in wooded areas are also at an increased risk due to the potential infection from bug bites.

Treatment Options for Viral Neurologic Infections

Treatment for vial neurological infections is often supportive. Treatment may depend on symptoms. Doctors may prescribe:

  • Anti-inflammatory medications to decrease swelling
  • Pain medications
  • IV fluids
  • Antiviral medications

Protecting Yourself From Viral Neurologic Infections

There are no vaccines to specifically prevent viral neurological infections, but there are certain steps you can take to reduce your risk:

  • Get other vaccines, such as mumps, rubella, and measles; these infections can cause complications, such as neurological infections
  • Use bug repellent when outside
  • Wash your hands often

Viral Liver Infections

Viral liver infections vary in severity. Liver viral diseases are called viral hepatitis. There are different forms of hepatitis, but they all involve inflammation of the liver.

Some people with viral hepatitis do not have symptoms at first. When symptoms do occur, they may look like:

  • Fatigue
  • Loss of appetite
  • Abdominal pain
  • Dark urine
  • Joint pain
  • Light-colored stool
  • Jaundice (yellowing of the skin)
  • Nausea

Types of Viral Liver Infections

  • Hepatitis A: Many infections of hepatitis A are mild, although more serious illness in possible
  • Hepatitis B: This form of infection can lead to chronic hepatitis and liver damage
  • Hepatitis C: Most infections involving hepatitis C are spread through contaminated blood
  • Hepatitis D: This form only occurs in people also infected with Hepatitis B
  • Hepatitis E: Hepatitis E is less common than the other forms of hepatitis

Transmission of Viral Liver Infections

Transmission for viral hepatitis varies partly by type. Hepatitis A and E are transmitted by eating foods or drinking water contaminated with feces.

Hepatitis B and C are spread largely from person to person via body fluids from someone that has the virus. It can be spread via contact with blood. Hepatitis B can also be transmitted through sexual contact with someone who is infected.

Who Is at Risk for Viral Liver Infections?

Certain factors have been identified that increase a person’s risk of developing viral hepatitis. For example, traveling to countries where sanitation practices may not be adequate may be a risk. Using illegal drugs and having unprotected sex with an infected person also increases your risk.

Treatment Options for Viral Liver Infections

Viral hepatitis treatment depends on the type of hepatitis. There is currently no specific treatment for hepatitis A, D, or E. Hepatitis B and C may be treated with medication.

Different medications are available that may be recommended:

  • Pegylated interferon-alpha for hepatitis B
  • Pegylated interferon along with ribavirin for people with hepatitis C
  • A liver transplant may be an option for people that develop liver failure

Protecting Yourself From Viral Liver Infections

Since there is no treatment for some forms of hepatitis, prevention is essential. One of the best ways to protect yourself from hepatitis A and B is by getting a vaccine. There is currently no vaccine for hepatitis C and D, and not a widely used vaccine for E.

For people who do not get a vaccination, there are steps you can take to lower your risk of contracting hepatitis:

  • Wash your hands before eating and handling food
  • When in other countries, drink bottled water instead of tap
  • Wash fruits and vegetables before eating
  • Do not share personal items, such as nail clippers and razors, which can transmit infection via blood
  • Use polyurethane or latex condoms during sex

Viral Sexually Transmitted Infections

Viruses may also lead to diseases that are sexually transmitted. The seriousness of a viral sexually transmitted disease can vary. For example, certain viral STDs are not life-threatening, but others can be serious.

Viral sexually transmitted infections can lead to a wide variety of symptoms. Certain symptoms may only affect the genitals. Other infections may lead to systemic symptoms. The exact symptoms may depend on the specific virus. Possible symptoms may be:

  • Pain during intercourse
  • Unusual vaginal discharge in women
  • Painful urination
  • Pelvic or lower abdominal pain
  • Discharge from the penis in men
  • Flu-like symptoms
  • Painful genital sores
  • Genital warts

Types of Viral Sexually Transmitted Infections

There are several different viruses that can lead to sexually transmitted diseases, such as those listed below.


HPV in an infection with the human papillomavirus. According to Harvard Medical School, about 80% of sexually active adults will get an HPV infection at some point in their life, but not all become symptomatic. There are many strains of HPV, including a few associated with cervical and testicular cancer.


HIV is an infection with the human immunodeficiency virus. The virus affects specific T cells in the immune system. It can affect a person’s ability to fight infections. Eventually, HIV can progress to AIDS. But advances in treatment have made HIV much more controllable.

Genital Herpes

This is a sexually transmitted disease that usually develops due to infection with the herpes simplex virus-2. Less commonly, herpes simplex virus-1, which causes cold sores, may also cause genital herpes.

Transmission of Viral Sexually Transmitted Infections

Viral sexually transmitted infections are spread from person to person through bodily fluids, including semen and vaginal secretions. Contact with blood from an infected person may also spread some types of viruses.

Who Is at Risk for Viral Sexually Transmitted Infections?

Anyone who has sexual intercourse can potentially contract a viral sexually transmitted infection, but certain factors may increase your risk. For example, improper or inconsistent use of condoms during sex increases a person’s risk.

Other risk factors include having multiple sexual partners and having a previous sexually transmitted disease.

Treatment Options for Viral Sexually Transmitted Infections

Treatment for viral sexually transmitted diseases is different than those caused by bacteria. According to the Mayo Clinic, viral sexually transmitted infections can be harder to treat than bacterial ones. Although the infections are manageable, they cannot always be cured.

Treatment may depend on the type of infection. In some instances, treatment involves managing symptoms and preventing outbreaks or flare-ups.

Treatment may include:

  • Antiviral drugs (different medications are used based on the virus)
  • Topical wart treatment to remove genital warts due to HPV may include imiquimod or podophyllin and podofilox
  • Procedures to remove genital warts, such as freezing or laser

Protecting Yourself from Viral Sexually Transmitted Infections

You can protect yourself from viral sexually transmitted infections in a few ways. Consider the following precautions:

  • Get vaccinated before becoming sexually active to prevent certain types of viral infections, such as HPV
  • Use a condom for every sexual act, including vaginally, oral and anal
  • Do not use an oil-based lubricant with a latex condom, since it could promote breakage

Complications From Viral Infections

Certain viral infections can lead to complications. The risk of complications may depend on the specific infection and what organs of the body were affected. For example, viral respiratory infections can become severe and eventually lead to bacterial infections, such as bacterial pneumonia. Viral infections can also lead to sepsis, which is a potentially deadly condition that causes organ failure.

Some people also develop lingering effects of a viral infection. Post-viral syndrome involves lingering fatigue for weeks or months after a viral infection. It is most common after a bout of the flu.

There are also other illnesses and conditions that are possibly triggered by different types of viral infections. For example, Guillain-Barre syndrome, which causes muscle weakness, may develop after a viral respiratory infection.

Viral infections can cause significant symptoms and illness. Taking steps to prevent infections, including getting vaccinations when available, is your best bet to stay well.

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