What do viruses do

But I can give you a general evolutionary explanation. Over long periods of evolution, you have a virus that comes into a host—a species—and spreads.

One of three things can then happen. One is that the virus can just die out for some reason—everybody can get immune, so the virus can no longer find a host, and it dies out. The second is that the host can die out. Some viruses that we have around with us—like the common cold virus—are like that. There are many viruses like that, such as HIV.

This coronavirus probably is, too. One example is cytomegalovirus, CMV. Many of us are infected with CMV, without consequence. Somebody can have normal vision on Friday and be totally, irreversibly blind on Monday. It varies greatly. You need really close intimate contact, blood transfusion or sexual contact. This coronavirus, by comparison, seems to be relatively stable so that it is able to survive in the environment for hours and maybe a few days, and others are even more stable than that.

Polio virus is stable even in sewage—you pick it up by drinking contaminated water. It passes through the gut, through the stomach, which is almost like pure hydrochloric acid—and the virus is still stable in that.

So some are amazingly tough, and some are quite fragile. Taylor McNeil can be reached at taylor. Skip to main content. A Tufts researcher explains the tiny infectious agents that can wreak havoc globally. Here, an image of an isolate from the first U. The spherical viral particles, colorized blue, contain cross-section through the viral genome, seen as black dots. They invade living, normal cells and use those cells to multiply and produce other viruses like themselves.

This can kill, damage, or change the cells and make you sick. Different viruses attack certain cells in your body such as your liver, respiratory system, or blood. When you get a virus, you may not always get sick from it. Your immune system may be able to fight it off. For most viral infections, treatments can only help with symptoms while you wait for your immune system to fight off the virus. Antibiotics do not work for viral infections.

There are antiviral medicines to treat some viral infections. Vaccines can help prevent you from getting many viral diseases. The information on this site should not be used as a substitute for professional medical care or advice. To see a virus, it is necessary to use a scanning electron microscope, which uses electrons instead of light to produce an image.

Another important fact is that there are many types of viruses. Some can just cause a common flu, while others can be more harmful such as HIV, Ebola or Coronavirus. And, there are viruses that enter the human body, but the immune system manages to fight them, so the person does not get sick. In short, viruses can replicate and create other viruses. This is possible as they can adapt very easily to any environment and any host. They are made to survive very difficult conditions.

Usually these microorganisms enter the body through the mouth, eyes, nose, genitals or through wounds, bites or any open wounds. Moreover, they are transmitted through different routes. Some diseases are spread by direct contact with infected skin, mucous membranes or body fluids.

There is also the possibility of indirect contact, when a person touches an object door, handle, table , which has the virus on it, when an infected person sneezes, coughs or talks or when the mucous membrane comes into contact with another person. In some other cases, the virus is transmitted through common vehicle such as contaminated food, water or blood. Finally, there are vectors: rats, snakes, mosquitoes etc.

These organisms enter the body and adhere to the cell surface. Depending on the type of virus, it seeks for cells in different parts of the body: liver, respiratory system or blood.

Once it has attached itself to the healthy cell, it enters it. When the virus is inside the cell, it will open up so that its DNA and RNA will come out and go straight to the nucleus. They will enter a molecule, which is like a factory, and make copies of the virus. These new copies of the virus millions of copies will leave the already infected cell to infect other healthy cells, where they will multiply again.

Infected cells can be damaged or die while hosting a virus.