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Why is hard to fight against viruses and what are they in the first place

D. Alwinsky, M.D. |
There are many things that present a danger for human but one of the smallest and most dangerous one is a virus.

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We live in symbiosis with other organism, bacteria and viruses, that help us live. Some bacteria is helpful in our colon, some viruses are protecting us from diseases, and sometimes things go nasty when a virus attacks our body.

A virus is a small organism which can't live for a long period of time outside a living cell. It may live on some surface, for example, for a few days, but it need a cell to reproduce. And its purpose, as is the purpose of every living being, is to reproduce.

When a virus finds a host cell, it enters it, release its DNA or RNA, and then it has a possibility to replicate. A virus forces the cell to serve it for a replication and that disturbs the normal functioning of the cell. That infected cell usually dies because of it, and when it dies, it releases new viruses ready to find another cells and spread infection further.

If a cell doesn't die, it may become altered in such a way that it loses its ability to divide normally and then it becomes cancerous.

There are two type of viruses: DNA and RNA viruses. Now, RNA viruses like to mutate. That means that they change during each replication and that is not good.

A range of problems viruses can cause is broad. Some kill the host, some cause a mild disease, some cause nothing, some cause chronic infections.

Viruses are specialized in a sense. Some like a particular type of cell, some infect only plants, some like animals, and some infect only people. This people types viruses is what interests us the most because they can cause very serious health conditions.

We said that viruses are specialized so we can roughly group viral infections in several groups regarding their attack target.

Respiratory infections occur when a virus attacks the nose, throat, upper airways, and lungs. We all heard about common cold, influenza and pneumonia and they are typical examples of respiratory infections.

We all know that children can get infections of upper or lower airways, so they have their own type of viruses that like children. There are also viruses like the Zika or rubella that like even fetus in pregnant women, so they attack a very sensitive population.

How can a virus jump from one person to another?

There are several ways. They may be inhaled, swallowed, transmitted via insects bites, transported during a sex act, or via infected blood. We see that they developed various way of spreading their population in many different ways.

What's even worse, there are viruses that once were present only in one environment and now travel the world thanks to our desire to travel. West Nile virus, Crimean-Congo hemorrhagic fever virus, Zika virus, Japanese encephalitis virus... They all can infect people around the world because human spread them while traveling.

So, what's the defense?

Thankfully, our body has some very effective defense mechanism. First, our skin is a barrier that's hard to go around. That's why soft tissue, like that in our nose, mouth or eyes may be an entry point to a virus that have no chance to get in through the skin. Hence the advice: Don't touch your face. You hands can cope with a virus but your nose can't. So, help it.

Then, there is out immune system. When a virus or some other foreign body enters human body, white blood cells jump to see what's going on and they "study" the foreign body to learn how to destroy it. When the body starts to fight, a great battle is underway and we have fever. That whole response is call immunity.

A good thing is, if the body survives, our white blood cells remember who entered our body unauthorized and next time they respond more quickly and kill invaders more effectively. If we get a vaccine against some type of a virus, our body learns how to cope with it and when the real danger comes it is ready to fight it.

Diagnosis can be done in several way. Some infection may be diagnosed just by looking what are the symptoms. Measles are good examples of a situation when you don't have to think too much, a typical rash is very known.

Next, similar cases also help. If there is influenza around, similar symptoms in several people will help the doctor to see what's going on.

In some other cases, a blood test is needed. Blood may be tested for antigens, those are proteins that our body produces to fight viruses, and we can see against which enemy the body is fighting. We can also make copies of viral genes from the blood. That makes easier for the doctor to see what is the exact type of the virus that attacked the body.

How can we protect?

Some measures are very simple, those are things that our parents thought us in the childhood. So, wash you hands with soap and water; do not eat raw food; avoid contact with infected people; sneeze into tissues; prevent bites; use safe sex. Simple. But effective.

What about drugs?

Well, the problem is, there are no effective antiviral drugs for many viral infections. There are drugs for some of them, such as against herpesviruses or HIV or hepatitis C., but for many of them we have no drugs. And when we do have, some antiviral drugs can be toxic to humans and viruses can develop resistance.

That means that in many cases we can treat only symptoms the best we can and hope the body will get that war.

Why there are no antiviral drugs when we know there are antibiotics that kill a very broad types of bacteria?

Bacteria are relatively large organisms, they reproduce outside the cells, and have many metabolic functions. We can target those metabolic functions with drugs.

Viruses, on the other hand, are small, they reproduce inside the cell, and they use the cells' own metabolic functions. So, the target is smaller, and we must be sure not to kill the cell or change its metabolic functions while targeting the virus. That's hard. That's why antiviral drugs are hard to develope, they are usually useful just for one virus or a very small types of very similar viruses.

So, viruses are nasty stuff. The battle against them is hard and sometimes drastic measures are needed to get the infection under control. To develop a vaccine or a cure we need many months which makes the situation even more difficult. The best advice we can give, that saves lives, is wash your hands and avoid the contact with an infected person. Those are measures centuries old but very effective.

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