Germs: Understand and protect against bacteria, viruses and infections
Mar 5, 2024 · Viruses are responsible for causing many diseases, including: Common cold. Influenza. Measles. Chickenpox and shingles. Coronavirus disease 2019, also called COVID-19. Antibiotics kill …
Bacterial vs. viral infections: How do they differ? - Mayo Clinic
Nov 25, 2025 · Viruses that become resistant to antivirals have affected treatment, including for genital herpes, HIV and, in 2008, for influenza (flu). Treating and preventing bacterial and viral infections In …
Cold and flu viruses: How long can they live outside the body?
Feb 24, 2024 · How long do cold and flu viruses stay alive after people with a virus cough or sneeze? Viruses that cause the common cold, the flu and COVID-19 may be able to infect someone for …
Encephalitis - Symptoms and causes - Mayo Clinic
May 16, 2024 · Encephalitis (en-sef-uh-LIE-tis) is inflammation of the brain. It can be caused by viral or bacterial infections, or by immune cells mistakenly attacking the brain. Viruses that can lead to …
Influenza (flu) - Symptoms and causes - Mayo Clinic
Dec 19, 2025 · Influenza viruses are constantly changing, with new strains appearing often. A person's first flu infection gives some long-term protection against similar strains of flu. But the vaccines …
Respiratory syncytial virus (RSV) - Mayo Clinic
Oct 4, 2023 · Respiratory syncytial virus (RSV) causes infections of the lungs and respiratory tract. It's so common that most children have been infected with the virus by age 2. Respiratory syncytial (sin …
Viral gastroenteritis (stomach flu) - Mayo Clinic
Apr 30, 2025 · Viral gastroenteritis is an intestinal infection that includes signs and symptoms such as watery diarrhea, stomach cramps, nausea or vomiting, and sometimes fever. The most common way …
Common cold - Symptoms and causes - Mayo Clinic
May 24, 2023 · Causes Many viruses can cause a common cold. Rhinoviruses are the most common cause. A cold virus enters the body through the mouth, eyes or nose. The virus can spread by: …
Coronavirus disease 2019 (COVID-19) - Symptoms and causes
Mar 13, 2026 · Coronavirus disease 2019 (COVID-19) is an illness caused by the virus SARS-CoV-2. Learn more about the symptoms, risks and ways to protect yourself.
Stomach flu: How long am I contagious? - Mayo Clinic
Mar 7, 2024 · Depending on which virus causes your stomach illness, you can be contagious from a few days to two weeks or more.