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 …
Pneumonia - Symptoms and causes - Mayo Clinic
Jun 13, 2020 · Pneumonia is an infection that inflames the air sacs in one or both lungs. The air sacs may fill with fluid or pus (purulent material), causing cough with phlegm or pus, fever, chills, and …
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: …
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 …
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 …
COVID-19, cold, allergies and the flu: What are the differences?
Oct 22, 2025 · The flu is caused by influenza A, B and C viruses. All of these viruses spread in similar ways. COVID-19 and the flu cause many of the same symptoms, but there are some differences. …
Cancer causes: Popular myths about the causes of cancer
Jan 21, 2026 · Misconceptions about cancer causes can lead to unnecessary worry about your health. Find out whether there's any truth to these common myths about the causes of cancer.
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 …
Food poisoning (foodborne illness) - Symptoms and causes
Aug 16, 2025 · Overview Food poisoning, a type of foodborne illness, is a sickness people get from something they ate or drank. The causes are germs or other harmful things in the food or drink. …