2023年2月4日 · To spread, a virus gets into a host's body and then into the host's cells. Then it takes over the host cell's machinery, using it to make more of the virus. Diseases caused by viruses include: COVID-19, caused by a coronavirus called SARS-CoV-2. Chickenpox, caused by the varicella-zoster virus. HIV, caused by the human immunodeficiency virus.

As a virus infects a group of people, the virus copies itself. During this process, the genetic code can randomly change in each copy. The changes are called mutations. If the coronavirus that causes COVID-19 changes in ways that make previous infections or vaccination less effective at preventing infection, people can get sick again.

2022年2月18日 · Infectious diseases commonly spread through the direct transfer of bacteria, viruses or other germs from one person to another. This can happen when an individual with the bacterium or virus touches, kisses, or coughs or sneezes on someone who isn't infected. These germs can also spread through the exchange of body fluids from sexual contact.

2024年3月5日 · There's a difference between infection and disease. Infection, often the first step in getting a disease, occurs when bacteria, viruses or other microbes that cause disease enter the body and begin to multiply. Disease happens when the infection damages cells in the body. Then symptoms of an illness appear.

Severe infection. People who have a severe C. difficile infection tend to lose too much bodily fluid, a condition called dehydration. They might need to be treated in a hospital for dehydration. C. difficile infection can cause the colon to become inflamed. It sometimes can form patches of raw tissue that can bleed or make pus.

2022年5月5日 · People often get H. pylori infection during childhood. Risk factors for H. pylori infection are related to living conditions in childhood, such as: Living in crowded conditions. Living in a home with many other people can increase your risk of H. pylori infection. Living without a reliable supply of clean water.

2022年11月8日 · Methicillin-resistant Staphylococcus aureus (MRSA) infection is caused by a type of staph bacteria that's become resistant to many of the antibiotics used to treat ordinary staph infections. Most methicillin-resistant Staphylococcus aureus (MRSA) infections occur in people who've been in hospitals or other health care settings, such as nursing ...

2022年2月18日 · Antibiotics are usually reserved for bacterial infections, because these types of drugs have no effect on illnesses caused by viruses. But sometimes it's difficult to tell which type of germ is at work. For example, pneumonia can be caused by a …

2024年11月8日 · Bacterial orchitis. Most often, bacterial orchitis is linked with or is the result of epididymitis. An infection of the urethra or bladder that spreads to the epididymis most often causes epididymitis. Sometimes, an STI is the cause. But this is a less common cause of orchitis in adults. Viral orchitis. The mumps virus most often causes viral ...

2022年2月11日 · During pregnancy, a listeria infection is likely to cause only mild signs and symptoms in the mother. The consequences for the baby, however, can be devastating — the baby can die in the womb or have a life-threatening infection within a few days of being born. Signs and symptoms of a listeria infection in a newborn can be subtle, but can ...