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 …
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 …
Diarrhea - Symptoms and causes - Mayo Clinic
Jan 18, 2025 · Causes A number of diseases and conditions can cause diarrhea, including: Viruses. Viruses that can cause diarrhea include Norwalk virus, also known as norovirus, enteric …
Medical Diseases & Conditions - Mayo Clinic
Explore comprehensive guides on hundreds of common and rare diseases and conditions from the experts at Mayo Clinic.
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 …
Common cold - Symptoms and causes - Mayo Clinic
May 24, 2023 · Germs called viruses cause a common cold. Often, adults may have two or three colds each year. Infants and young children may have colds more often. Most people recover from a …
Long COVID: Lasting effects of COVID-19 - Mayo Clinic
Aug 23, 2024 · COVID-19 can have lasting symptoms that affect many parts of the body. Learn more about the symptoms and effects of long COVID.
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 …
Coronavirus disease 2019 (COVID-19) - Symptoms and causes
Oct 21, 2025 · 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.