Viremia is a medical term for viruses present in the bloodstream. A virus is a tiny, microscopic organism made of genetic material inside a protein coating. Viruses depend on a living host, like a human or animal, for survival. They survive by invading cells and using those cells to multiply and produce other viruses. This is called viral replication.
There are many different types of viruses, and they are highly contagious. Some viruses only infect the skin, but others can move into the bloodstream. The signs and symptoms of viremia depend on which virus you have. Once in the blood, a virus has access to almost every tissue and organ in your body. While viremia commonly occurs during a viral infection, it’s only dangerous in certain infections.
Viremia can be classified into types. These include:
- primary viremia: spread of the virus into the blood from the initial site of infection (where the virus first entered the body)
- secondary viremia: spread of the virus to other organs that come into contact with the blood where the virus replicates and then enters the bloodstream once more
- active viremia: viremia caused by the replication of viruses after they enter the blood
- passive viremia: entry of the virus directly into the bloodstream without the need for viral replication, such as from a mosquito bite
Viremia is caused by a virus. Actually, many different types of viruses can cause viremia.
A virus attaches to one of your cells, releases its DNA or RNA, takes control of the cell, and forces it to replicate the virus. Examples of viruses that enter the bloodstream include:
If you have viremia, chances are the infection spread from someone else that you were in close contact with. Some of the ways viruses can be spread include:
- sexual contact
- blood to blood transmission (for example, from drug users sharing needles with an infected person)
- via the respiratory tract (contact with saliva, coughing, sneezing, etc.)
- through the bite of an infected insect or animal, like a mosquito or a tick
- through a cut in the skin
- fecal-oral (contact with feces)
- from mother to fetus
- through breast milk
The most common route of transmission for viruses is through the respiratory tract. But not all viruses can be spread this way. For example, HIV can only be passed from person to person from blood or bodily fluids and sometimes from mother to fetus. Viruses must invade a living cell to reproduce, and they can’t live for long without a host.
Some viruses enter the bloodstream directly through the bite of an infected insect or animal, such as Zika virus, which can be spread by a bite from an infected mosquito.
The symptoms of viremia vary depending on which type of virus has entered the body.
In general, viral infections cause the following symptoms:
- body aches
- joint pain
You may not get sick from a viral infection. Sometimes, your immune system can fight it off before you have any symptoms.
Your doctor may be able to diagnose viremia by assessing your symptoms. For example, muscle aches, fever, and swollen lymph glands might indicate that you have viremia. And your doctor may also ask you some questions. Your answers to the following might assist in a diagnosis:
- Have you been in contact with a sick individual?
- Have you recently traveled out of the country or to an area where there is a known outbreak of a certain virus?
- Have you had unprotected sex?
- Have you shared any needles?
- Have you had a recent blood transfusion?
- Have you been bitten by an animal or tick recently?
Your doctor can also look for the presence of viruses in your bloodstream through a blood test. After drawing blood, the sample will be tested in a laboratory using a technique called polymerase chain reaction (PCR). A PCR can detect viral DNA or RNA.
Once a virus enters the bloodstream, it has access to almost every tissue and organ in your body. Some viruses target specific tissues and might be named after the specific tissue they infect. For example:
- An enteric virus replicates in the gastrointestinal system.
- A neurotropic virus replicates in cells of the nervous system.
- A pantropic virus can replicate in many organs.
The virus injures your cells and may induce apoptosis, or programmed cell death. Viremia can lead to complications if your immune system can’t fight it off, or if you don’t receive treatment.
Complications will depend on what specific virus has entered the bloodstream. Some complications include:
- brain damage or neurological problems (such as with the poliovirus)
- skin lesions
- inflammation of the liver (hepatitis)
- weakened immune system
- inflammation of the heart
Treatment depends on the virus. Sometimes, treatment involves waiting for your immune system to clear the infection on its own. In the meantime, you can treat your symptoms to help make you feel better. Treatments can include:
- ingesting fluids
- taking acetaminophen (Tylenol) or nonsteroidal anti-inflammatory drugs (NSAIDS) for fever and body aches
- taking anti-diarrheal medications such as loperamide (Imodium)
- using anti-itch creams for rashes
- using nasal decongestants
- using throat-numbing lozenges for a sore throat
Antibiotics don’t work for viral infections. There are certain medications called antivirals that can work in the bloodstream to stop the virus from replicating. Examples of antiviral medications include:
- ganciclovir (Zirgan)
- ribavirin (RibaTab)
- famciclovir (Famvir)
- immune globulin
Antiviral drugs are difficult to create and they can also be toxic to human cells. In addition, viruses can develop resistance to these drugs. Fortunately, vaccines are available to prevent infections with many of the most dangerous viruses. A vaccine is a substance made from part of a virus or a deactivated virus that is injected into your body. Vaccines help prevent infection by stimulating the body's immune system to recognize and destroy a virus.
The outlook depends on the type of virus you are infected with. Some virus strains are deadlier than others. In general, the earlier an infection is diagnosed, the better the outlook. People with compromised immune systems often have a worse outlook. However, medical advancements and the invention of vaccines have greatly improved the outlook for viremia over the past few decades.