Viral Diseases 101

From http://www.healthline.com

Medically reviewed by Daniel Murrell, M.D. — Written by Jill Seladi-Schulman, Ph.D. — Updated on March 29, 2019

Viruses are very small infectious agents. They’re made up of a piece of genetic material, such as DNA or RNA, that’s enclosed in a coat of protein.

Viruses invade cells in your body and use components of those cells to help them multiply. This process often damages or destroys infected cells.

A viral disease is any illness or health condition caused by a virus. Read on to learn more about some of the main types of viral diseases:

They aren’t always contagious
Not all viral diseases are contagious. This means they aren’t always spread from person to person. But many of them are. Common examples of contagious viral diseases include the flu, the common cold, HIV, and herpes.

Other types of viral diseases spread through other means, such as the bite of an infected insect.

Respiratory viral diseases
Respiratory viral diseases are contagious and commonly affect the upper or lower parts of your respiratory tract.

Common symptoms of a respiratory viral disease include:

runny or stuffy nose
coughing or sneezing
fever
body aches
Examples

Examples of respiratory diseases include:

flu
common cold
respiratory syncytial virus infection
adenovirus infection
parainfluenza virus infection
severe acute respiratory syndrome (SARS)
Transmission

Respiratory viruses are spread by droplets generated through coughing or sneezing. If someone with a viral illness coughs or sneezes nearby and you inhale these droplets, you may develop the disease.

These viruses can also be spread through contaminated objects, such as doorknobs, tabletops, and personal items. If you touch one of these objects and then touch your nose or eyes, you could develop a disease.

Treatment

Respiratory viral diseases usually heal on their own. But over-the-counter (OTC) medications, including nasal decongestants, cough suppressants, and pain relievers, can help to reduce symptoms.

In addition, Tamiflu, an antiviral drug, is sometimes prescribed if someone is in the very early stages of developing the flu.

Prevention

The best way to avoid respiratory viral diseases is to practice good personal hygiene. Wash your hands often, cover your mouth when you cough or sneeze, and limit your interactions with people who show symptoms of a respiratory condition.

There’s also a vaccine that can help to reduce your risk of getting the seasonal flu.

Gastrointestinal viral diseases
Gastrointestinal viral diseases affect your digestive tract. The viruses that cause them are contagious and usually lead to a condition called gastroenteritis, also called the stomach flu.

Common symptoms of gastrointestinal viral diseases include:

abdominal cramps
diarrhea
vomiting
Examples

Examples of gastrointestinal viral diseases include:

norovirus infection
rotavirus infection
some adenovirus infections
astrovirus infection
Transmission

Gastrointestinal viruses are shed in the stool during bowel movements. Food or water that’s been contaminated by feces can spread the virus to others. You can also get the virus from sharing utensils or personal objects with someone who has a virus.

Treatment

There aren’t any treatments for gastrointestinal viral diseases. In many cases, they resolve on their own within a day or two. In the meantime, drink plenty of fluids to replace those lost from diarrhea or vomiting.

Prevention

You can prevent gastrointestinal viral diseases by washing your hands often, especially after using the bathroom. Wiping down contaminated surfaces and not sharing personal items or eating utensils can also help.

There’s also a vaccine for rotavirus that’s recommended as part of a child’s vaccination schedule.

Exanthematous viral disease
Exanthematous viruses cause skin rashes. Many of them cause additional symptoms as well.

Many of the viruses in this category, such as the measles virus, are highly contagious.

Examples

Examples of exanthematous viral diseases include:

measles
rubella
chickenpox/shingles
roseola
smallpox
fifth disease
chikungunya virus infection
Transmission

Many exanthematous viruses are spread through respiratory droplets from the cough or sneeze of someone with the virus.

Other exanthematous viral diseases, such as chickenpox and smallpox, can be transmitted by coming into contact with fluid in broken skin lesions.

Shingles only occurs in people who’ve had chickenpox at some point. It’s a reactivation of the varicella-zoster virus that’s been lying dormant in your cells.

Chikungunya virus is spread through a mosquito bite and cannot be transmitted from person to person.

Treatment

Treating exanthematous viral diseases focuses on managing symptoms. Fever-reducing medications, such as acetaminophen, can help with some of the more bothersome symptoms.

Antiviral drugs, such as acyclovir, may be given for chickenpox or shingles.

Prevention

Measles, rubella, chickenpox, shingles, and smallpox can all be prevented through vaccination. You can reduce your risk of a chikungunya virus infection by protecting yourself from mosquito bites.

Learn more about viral rashes.

Hepatic viral diseases
The hepatic viral diseases cause inflammation of the liver, known as viral hepatitis. The most commonTrusted Source types of viral hepatitis are hepatitis A, B, and C.

It is worth noting that diseases caused by other viruses, such as cytomegalovirus and the yellow fever virus, can also affect the liver.

Examples

Examples of hepatic viral diseases include:

hepatitis A
hepatitis B
hepatitis C
hepatitis D
hepatitis E
Transmission
Hepatitis B and C can be transmitted from person to person through bodily fluids. Sharing items that come in to contact with blood, such as needles or razors, can also spread the virus. Hepatitis B can be spread through sexual contact.

People get hepatitis A and E by consuming food or water that’s been contaminated with feces from someone with the virus.

You can only develop hepatitis D if you already have the hepatitis B virus.

Treatment

Treatments for hepatitis B, C, and D focus on managing symptoms. In some cases, a doctor might prescribe medication, such as antiviral drugs.

Treatment of hepatitis A and E involves supportive measures, such as getting plenty of rest, drinking fluids, and avoiding alcohol.

Prevention

There are vaccines for both hepatitis A and hepatitis B. There’s also a vaccine for hepatitis E, but it’s not available in the U.S.

Other ways to prevent viral hepatitis include not sharing needles or razors, practicing safe sex, and avoiding food or drinks that may be contaminated by feces.

Cutaneous viral diseases
Cutaneous viral diseases cause lesions or papules to form on the skin. In many cases, these lesions can stick around for a long time or come back after disappearing for a while.

Examples

Examples of cutaneous viral diseases include:

warts, including genital warts
oral herpes
genital herpes
molluscum contagiosum

Transmission
Many neurologic viruses are spread through the bite of an infected animal or bug, such as a mosquito or tick.

Other viruses, such poliovirus and other enteroviruses, are quite contagious and spread through close contact with someone with the virus. Contaminated objects can also contribute to the spread of these viruses.

Treatment

There’s no specific treatment for people with mild viral meningitis or encephalitis. Getting plenty of rest, staying hydrated, and taking OTC anti-inflammatories to ease pain or headaches can all help. In some cases, antiviral medication may be prescribed.

Polio or severe cases of meningitis or encephalitis may require additional treatment, such as breathing assistance or IV fluids.

If an animal that’s suspected to have the rabies virus bites you, you’ll be given a series of shots to help prevent the rabies virus from infecting you.

Prevention

There’s a vaccine for both poliovirus and the mumps virus, which can cause meningitis and encephalitis.

Practicing good hygiene, avoiding close contact with those who have the virus, and protecting against insect bites can all help to reduce the spread of encephalitis and meningitis.

To reduce the risk of spreading rabies, keep your pets vaccinated and avoid approaching wild animals.

Bottom line
There are many viral diseases. Some, such as the common cold or the stomach flu, are minor and go away on their own within a few days. Others, however, are more serious.

Unlike bacterial infections, viral diseases don’t respond to antibiotics. Instead, treatment usually focuses on managing symptoms and supporting the immune system with plenty of rest and hydration.

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