Viral Diseases: Causes

What causes viral diseases?

Viral infections occur when a virus enters the body and invades the inside of the body’s cells in order to reproduce. If the body’s immune system is unable to fight off the virus, it multiplies and spreads to other cells, repeating the process and leading to a widespread infection.

Types of viruses

There are many types of viruses that cause a wide variety of viral infections or viral diseases. In fact, there are more than 200 different viruses that can cause a cold or an upper respiratory infection. Other common viruses include the following:

• Epstein-Barr virus causes infectious mononucleosis (cytomegalovirus causes a very similar disease in some people).

• Human immunodeficiency virus (HIV) causes AIDS.

• Human papillomaviruses (HPV) cause HPV infection, cervical dysplasia, genital warts, and cervical cancer.

• Influenza viruses, such as H1N1, cause influenza (flu).

• Respiratory syncytial virus (RSV) causes lower respiratory tract infections in young children.

• Rhinoviruses cause the common cold.

• Rotavirus, enteroviruses and noroviruses cause viral gastroenteritis.

• Varicella zoster virus causes shingles and chickenpox.

• West Nile virus causes West Nile fever.

Various ways to become infected with a virus

You can catch a virus in a variety of ways including:

• Being bitten by an animal infected with a virus

• Being bitten by an insect infected with a virus, such as with West Nile virus

• Breathing in air-borne droplets contaminated with a virus

• Eating food or drinking water contaminated with a virus

• Having sexual contact with a person who is infected with a sexually transmitted virus

• Sharing needles for tattooing or drug use with an infected person

• Touching infected feces or body fluids and not washing your hands before eating or touching your mouth, eyes or nose

• Touching surfaces contaminated with a virus

• Transmission of a virus from an infected mother to her baby during pregnancy or delivery

What are the risk factors for contracting viral diseases?

Viral diseases can occur in any age group or population. Everybody contracts viral diseases during their life, although in some cases, the virus does not cause obvious symptoms. Risk factors for catching a viral disease or developing complications of a viral disease include:

• Advanced age

• Compromised immune system due to an immunodeficiency disorder, HIV/AIDS, cancer or cancer treatment, kidney disease, or other condition

• History of chronic disease, such as asthma, COPD, diabetes, tuberculosis, or heart disease

• Malnourishment

• Not getting enough rest and having high levels of stress

• Not washing your hands frequently, especially before eating or after using the restroom, or after touching common surfaces

• Sharing needles to inject drugs or for tattooing

• Unprotected sex including vaginal, oral and anal sex with a partner who has had one or more other sexual partners

• Young age including infancy and elementary-school-age children

Reducing your risk of viral diseases

You can lower your risk of catching or spreading a viral disease by:

• Abstaining from sexual activity, or only engaging in sexual activities within a mutually monogamous relationship in which neither partner is infected with a sexually transmitted disease

• Avoiding contact of your hands with your eyes, nose and mouth, which can transmit a virus into the body

• Avoiding contact with a person who has a viral disease

• Covering your mouth and nose with your elbow (not your hand) or a tissue when sneezing or coughing

• Eating a well-balanced diet that includes sufficient amounts of fruits and vegetables

• Sufficient rest

• Using a new condom for each sex act

• Using a sterile, unused needle for each act of tattooing or injectable drug use

• Using appropriate antibacterial cleaners to clean your hands and surfaces

• Vaccination as recommended by your health care provider for viral diseases, such as chickenpox, shingles, influenza, HPV, hepatitis B, hepatitis A, measles, and mumps

• Washing your hands with soap and water for at least 15 seconds after contact with a person who has a viral disease, before eating, or after using the restroom or touching feces, body fluids, surfaces, or foods that are potentially contaminated with viruses