Viruses and infection

In addition, Tamiflu, an antiviral drug, is sometimes prescribed if someone is in the very early stages of developing the flu. The best way to avoid respiratory viral diseases is to practice good personal hygiene. Wash your hands often, cover your mouth when you cough or sneeze, and limit your interactions with people who show symptoms of a respiratory condition.

Gastrointestinal viral diseases affect your digestive tract. The viruses that cause them are contagious and usually lead to a condition called gastroenteritis , also called the stomach flu. Gastrointestinal viruses are shed in the stool during bowel movements. You can also get the virus from sharing utensils or personal objects with someone who has a virus.

In many cases, they resolve on their own within a day or two. In the meantime, drink plenty of fluids to replace those lost from diarrhea or vomiting. You can prevent gastrointestinal viral diseases by washing your hands often, especially after using the bathroom. Wiping down contaminated surfaces and not sharing personal items or eating utensils can also help. Many exanthematous viruses are spread through respiratory droplets from the cough or sneeze of someone with the virus.

Other exanthematous viral diseases, such as chickenpox and smallpox, can be transmitted by coming into contact with fluid in broken skin lesions. Chikungunya virus is spread through a mosquito bite and cannot be transmitted from person to person.

Treating exanthematous viral diseases focuses on managing symptoms. Fever-reducing medications, such as acetaminophen, can help with some of the more bothersome symptoms. Measles, rubella, chickenpox, shingles, and smallpox can all be prevented through vaccination. You can reduce your risk of a chikungunya virus infection by protecting yourself from mosquito bites. Learn more about viral rashes. The hepatic viral diseases cause inflammation of the liver, known as viral hepatitis.

The most common types of viral hepatitis are hepatitis A, B, and C. It is worth noting that diseases caused by other viruses, such as cytomegalovirus and the yellow fever virus, can also affect the liver. Hepatitis B and C can be transmitted from person to person through bodily fluids. Sharing items that come in to contact with blood, such as needles or razors, can also spread the virus. Hepatitis B can be spread through sexual contact. Treatments for hepatitis B, C, and D focus on managing symptoms.

Section Navigation. Facebook Twitter LinkedIn Syndicate. How Do Infections Occur? Three things are necessary for an infection to occur: Source: Places where infectious agents germs live e.

Source Susceptible Person Transmission Source. People are one source of germs including: Patients Healthcare workers Visitors and household members People can be sick with symptoms of an infection or colonized with germs not have symptoms of an infection but able to pass the germs to others. Examples of environmental sources of germs include: Dry surfaces in patient care areas e. Susceptible Person. Certain medications used to treat medical conditions, such as antibiotics, steroids, and certain cancer fighting medications increase the risk of some types of infections.

Lifesaving medical treatments and procedures used in healthcare such as urinary catheters, tubes, and surgery increase the risk of infection by providing additional ways that germs can enter the body. The virus-first hypothesis suggests that viruses evolved from complex molecules of nucleic acid and proteins either before or at the same time as the first cells on Earth appeared, billions of years ago. When a viral disease emerges, it is not always clear where it comes from.

A virus exists only to reproduce. When it reproduces, particles spread to new cells and new hosts. The features of a virus affect its ability to spread. Some viruses can remain active on an object for some time. If a person with the virus on their hands touches an item, the next person can pick up that virus by touching the same object. The object is known as a fomite. Viruses often change over time. Some of these changes are very small and do not cause concern, but others can be more significant.

Significant changes could make a virus more transmissible, as has been the case with the B. They may also help the virus evade the immune system or existing treatments. For example, doctors use several drugs in combination to treat HIV so that it is harder for the virus to develop resistance to treatment. Influenza viruses can also do so-called antigenic shift. This can happen if a host cell has become infected with two different types of influenza virus.

For instance, pigs can often serve as a mixing vessel for avian and human influenza viruses. Some viruses, such as HPV, can lead to cancer. The full impact of a virus can take time to appear, and sometimes there may be a secondary effect.

For example, the herpes zoster virus can cause chickenpox. The person recovers, but the virus may stay in the body. Years later, it may cause shingles in the same individual. Coronaviruses are a large family of viruses and include viruses that cause the common cold. However, it has changed many times since scientists first identified it in China. By September , scientists had logged over 12, mutations, and the development continues.

Some variants are more transmissible and more likely to cause severe illness than others. The main concern with new variants is the unpredictability of their impact. The main symptoms of COVID are dry cough , fatigue , and fever, but there are many possible symptoms. Anyone who has symptoms should seek a test. It is also important to self-isolate until 10 days after symptoms appear and when no fever has been present for 24 hours.

Other bacteria can directly invade and damage tissues. Some infections caused by bacteria include:. Viruses are much smaller than cells. In fact, viruses are basically just capsules that contain genetic material. To reproduce, viruses invade cells in your body, hijacking the machinery that makes cells work. Host cells are often eventually destroyed during this process. There are many varieties of fungi, and we eat several of them.

Mushrooms are fungi, as are the molds that form the blue or green veins in some types of cheese. And yeast, another type of fungus, is a necessary ingredient in most types of bread. Other fungi can cause illness. One example is candida — a yeast that can cause infection. Candida can cause thrush — an infection of the mouth and throat — in infants and in people taking antibiotics or who have an impaired immune system. Fungi are also responsible for skin conditions such as athlete's foot and ringworm.

Protozoans are single-celled organisms that behave like tiny animals — hunting and gathering other microbes for food. Many protozoans call your intestinal tract home and are harmless. Others cause diseases, such as:. Protozoans often spend part of their life cycles outside of humans or other hosts, living in food, soil, water or insects. Some protozoans invade your body through the food you eat or the water you drink.

Others, such as malaria, are spread by mosquitoes. Helminths are among the larger parasites. The word "helminth" comes from the Greek word for worm. If these parasites — or their eggs — enter your body, they take up residence in your intestinal tract, lungs, liver, skin or brain, where they live off your body's nutrients. Helminths include tapeworms and roundworms. There's a difference between infection and disease. Infection, often the first step, occurs when bacteria, viruses or other microbes that cause disease enter your body and begin to multiply.

Disease occurs when the cells in your body are damaged — as a result of the infection — and signs and symptoms of an illness appear.