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Basics
- Summary
- Start Here
- Diagnosis and Tests
- Prevention and Risk Factors
Learn More
- Related Issues
- Specifics
- Genetics
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- Images
Research
- Clinical Trials
- Journal Articles
Resources
- Find an Expert
For You
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- Patient Handouts
Summary
What are viruses?
Viruses are very tiny germs. They are made of genetic material (either DNA or RNA) inside of a protein coating. There are a huge number of viruses on earth. Only a small number of them can infect humans. Those viruses can infect our cells, which may cause disease. Some of the diseases that viruses can cause include the common cold, the flu, COVID-19, and HIV.
How are viruses spread?
Viruses can be spread in different ways:
- Through droplets and particles that are breathed out by someone who has the infection. You might breathe in the droplets or particles, or they could land on your mouth, nose, or eyes.
- By touching surfaces or objects that have the virus on them and then touching your mouth, nose, or eyes.
- From the pregnant parent to the baby during pregnancy.
- Through contaminated food or water.
- By being bitten by an infected insect or animal.
- Through sexual contact (usually vagin*l, anal and oral sex) with someone who has the infection.
How do viruses cause disease?
Viruses are like hijackers. They invade living, normal cells. They then use those cells to multiply (make copies of themselves). This process is also called replication. The process can kill, damage, or change the infected cells. Sometimes this can make you sick. The symptoms can range from mild to very severe. Other times, your immune system may be able to fight it off and you may not have any symptoms.
Each different virus usually only infects one type of cell in your body. For example, hepatitis viruses affect the cells in the liver. HIV infects a certain type of immune system cell.
What are the treatments for viral infections?
For most viral infections, treatments can only help with symptoms while you wait for your immune system to fight off the virus. There are antiviral medicines to treat some viral infections. Antibiotics do not work for viral infections.
Can viral infections be prevented?
Vaccines can help prevent you from getting many viral diseases. You may be able to prevent some viral infections by:
- Proper hand washing.
- Paying attention to food safety.
- Cleaning surfaces that may be infected with germs.
- Avoiding contact with wild animals.
- Preventing insect bites by using insect repellent when you go outdoors. If you travel to an area that has a high risk of diseases from insect bites, also wear long pants, shirts, and socks.
- Practicing safe sex (using a condom every time you have anal, vagin*l, or oral sex).
- Avoiding close contact with people who are sick.
Start Here
- Bacterial vs. Viral Infections: How Do They Differ? (Mayo Foundation for Medical Education and Research) Also in Spanish
- Overview of Viral Infections (Merck & Co., Inc.) Also in Spanish
Diagnosis and Tests
- Immunoglobulins Blood Test
(National Library of Medicine) Also in Spanish - PCR Tests (National Library of Medicine) Also in Spanish
- Rapid Tests (National Library of Medicine) Also in Spanish
- Respiratory Pathogens Panel (National Library of Medicine) Also in Spanish
Prevention and Risk Factors
- Germs and Hygiene: MedlinePlus Health Topic (National Library of Medicine) Also in Spanish
- Infection Control: MedlinePlus Health Topic (National Library of Medicine) Also in Spanish
Related Issues
- How a Virus Infects the Body (National Jewish Health) - PDF
- How Infections Spread (Centers for Disease Control and Prevention)
- Viruses that Can Lead to Cancer (American Cancer Society)
Specifics
- About Adenovirus (Centers for Disease Control and Prevention)
- About Enterovirus D68 (Centers for Disease Control and Prevention)
- About Hand, Foot, and Mouth Disease (Centers for Disease Control and Prevention) Also in Spanish
- About Human Parainfluenza Viruses (HPIVs) (Centers for Disease Control and Prevention)
- Clearing the Air: All About Airborne Viruses (National Institutes of Health) Also in Spanish
- HTLV-1-Associated Myelopathy (HAM)/Tropical Spastic Paraparesis (TSP) (National Institute of Neurological Disorders and Stroke)
- Human Metapneumovirus (hMPV) (American Lung Association)
- Molluscum Contagiosum (Centers for Disease Control and Prevention)
- Non-Polio Enterovirus (Centers for Disease Control and Prevention)
Genetics
- Genomics and Virology (National Human Genome Research Institute)
Images
- Molluscum Contagiosum (VisualDX)
- Viral Exanthem (VisualDX)
Clinical Trials
- ClinicalTrials.gov: Adenoviridae Infections (National Institutes of Health)
- ClinicalTrials.gov: Coxsackievirus Infections (National Institutes of Health)
- ClinicalTrials.gov: Enterovirus (National Institutes of Health)
- ClinicalTrials.gov: Hand, Foot and Mouth Disease (National Institutes of Health)
- ClinicalTrials.gov: Virus Diseases (National Institutes of Health)
Journal Articles References and abstracts from MEDLINE/PubMed (National Library of Medicine)
Children
- Adenovirus (Nemours Foundation) Also in Spanish
- Coxsackievirus Infections (For Parents) (Nemours Foundation) Also in Spanish
- Enterovirus Infections (For Parents) (Nemours Foundation) Also in Spanish
- Hand, Foot, and Mouth Disease (VisualDX)
- Parechovirus (For Parents) (Nemours Foundation) Also in Spanish
- Roseola (Sixth Disease) (VisualDX)
- Viral Exanthem (VisualDX)
Patient Handouts
- ECHO virus (Medical Encyclopedia) Also in Spanish
- Enterovirus D68 (Medical Encyclopedia) Also in Spanish
- Hand-foot-mouth disease (Medical Encyclopedia) Also in Spanish
- Herpangina (Medical Encyclopedia) Also in Spanish
- Molluscum contagiosum (Medical Encyclopedia) Also in Spanish
- Parainfluenza (Medical Encyclopedia) Also in Spanish
- Roseola (Medical Encyclopedia) Also in Spanish
