Viremia is a term that describes the presence of viruses in the blood. Viruses are microscopic organisms that survive and multiply inside living hosts, such as animals and humans.
Minor cases of viremia can be relatively harmless and resolve on their own. However, if the infection becomes severe or causes infection in vital organs, it may lead to organ failure or sepsis, which is life-threatening.
Viremia is the medical term for when viruses enter the bloodstream.
Viruses are parasitic, meaning they rely on an outside host for their survival and reproduction. Some viruses can enter the bloodstream, leading to viremia.
Viruses are minuscule — 45,000 times smaller than the width of a human hair. They come in many shapes and sizes, but all known viruses share the same basic structure.
Viruses are made of genetic material, either DNA or RNA, which is wrapped in a protective protein covering called a capsid.
Viruses can be highly contagious and work by hiding from the immune system, taking over host cells and forcing them to produce more of the virus.
Many cases of viremia are mild or harmless, but if the infection becomes severe or affects the vital organs, it may lead to organ failure or sepsis.
Sepsis is an extreme immune response to an infection and is life-threatening, especially in those with compromised immune systems.
Most viruses can potentially cause viremia. But while there are many types of viruses in the world, only some are known to cause illness in humans.
Some common or well-known causes of viremia include:
- HIV types 1 and 2
- viral pneumonia
- viral meningitis
- varicella zoster virus (chicken pox or shingles)
- measles, mumps, and rubella
- human papillomavirus (HPV)
- hepatitis B and C
- Zika virus
- West Nile Virus
- avian influenza virus
- dengue fever
- yellow fever
- Japanese encephalitis virus
- Rift Valley fever virus
Throughout history, viruses have survived by being incredibly adaptable and resilient to life both inside and even outside of a host.
Many viruses use body fluids to spread between hosts. However, some viruses can live on a dry, non-porous surface, such as a plastic container, for 7 days or more.
Common ways viruses spread include:
- fecal-oral route (accidental ingestion of fecal matter)
- sexual contact
- contact with saliva or mucus (from coughing, sneezing, or touching, for example)
- mosquito or insect bites
- congenitally, or from mother to fetus during pregnancy or childbirth
- blood transfusion
- organ donation
- through cuts or severe injuries
The symptoms of viremia often depend on the cause of the infection, but many viral infections cause a similar set of symptoms.
Common signs of viral infection and viremia include:
- general exhaustion
- muscle and joint weakness, pain, and aching
- a headache
- dizziness or light-headedness
- diarrhea, nausea, or vomiting
- runny or congested nose
- a sore throat
- a cough
- poor appetite
Viremia is classified into types depending on how the virus infected the bloodstream.
Types of viremia include:
- Primary viremia: This is when the virus enters the bloodstream.
- Secondary viremia: This is when viremia has caused an infection in another organ or tissue by spreading through the bloodstream.
Sometimes the name of the related viral infection is listed to further describe cases of viremia, such as HIV-viremia or West Nile-viremia.
Sometimes, a doctor may be able to diagnose viremia based on a person’s medical history and a physical examination.
Blood tests and blood cultures may also be necessary to determine or confirm the specific cause of viral infections and viremia.
In some cases, a doctor may diagnose viremia by comparing a person’s symptoms with those of other viral infections that someone has potentially been exposed to. A doctor is more likely to do this during an outbreak or epidemic of a specific virus.
For most viral infections, treatment involves dealing with the symptoms of the infection rather than the virus itself.
Typical therapies for viral infections and viremia include:
- fluids, especially those high electrolytes
- anti-inflammatory and pain medications
- antiemetic or anti-nausea medications
- clear fluid foods, such as clear soup broths
- anti-diarrheal medications
- anti-itch creams, such as hydrocortisone creams
- nasal decongestant medications and rinses
- throat lozenges or numbing sprays
- cough syrups
In severe cases, fluids may be given intravenously in a hospital.
A few antiviral medications exist, but each medicine is usually only effective against a specific virus or family of viruses.
In many cases, antiviral medications can only help reduce the spread or severity of viral infections, but not cure them.
Some antiviral medications also work predominately by strengthening the immune system response, not destroying or disabling the virus.
Antiviral medications are also usually non-specific, meaning they target healthy cells alongside viruses.
Another drawback of antiviral medications is that viruses can evolve and become immune to the medication, especially if the drugs are not taken correctly.
In some cases of viremia, doctors will recommend a treatment called interferon. Interferon is a group of around 20 related signaling-proteins made by human immune cells in response to viruses.
So far, antiviral medications exist to help treat:
- hepatitis C
There are also vaccines available that can significantly reduce the risk of developing some of the most serious and prevalent human viral infections.
Vaccines work by exposing a small portion of the virus to the body’s immune system, allowing it to recognize and destroy invading viruses before they can initiate an infection.
Most people receive an initial set of vaccinations or immunizations when they are very young. They will then receive new vaccinations periodically throughout early childhood and adulthood.
Many people will also receive vaccinations for specific viruses and diseases before traveling internationally.
How long these vaccines are effective for usually depends on the type of vaccine. Common effective periods range from a few months to decades.
Some vaccines can act as preventives, which can help treat active cases of the same virus.
Some viral infections with widely available vaccines include:
- hepatitis A and B
- chickenpox and shingles
- yellow fever
Anyone who does not receive the standard recommended vaccines is far more vulnerable to viral infection and its complications than people with an up-to-date vaccination history.
Factors that influence the risk of complications with viremia include:
- the type of virus
- the severity of the infection
- immune status
- additional health conditions
- vaccination history
Most minor cases of viremia eventually resolve on their own without direct medical treatment.
Viremia can allow viruses to spread through the blood and infect tissues and organs throughout the body.
Since many viruses kill host cells, long-term or severe viremia can cause damage to infected tissues and organs.
Viremia can also weaken the immune system, making it easier to develop other types of viral, bacterial, and fungal infections.
Very severe or untreated viremia can also result in sepsis, an extreme immune response where the body accidentally damages its own healthy tissues. Sepsis is sometimes called blood poisoning.
If untreated, sepsis can be life-threatening and leads to seizure, organ failure, coma, and eventually death.
Many people and animals develop viremia each year, but most cases resolve with basic at-home care.
Preventive measures, such as vaccines and immunoglobins, can significantly reduce the risk of developing some types of viral infection.
However, some viral infections, including meningitis, hepatitis C, and HIV can be life-threatening and require immediate medical care. Treatment may include intravenous fluids, antiviral medications, immunoglobins, and forms of interferon.
Anyone who experiences severe or long-lasting symptoms from a viral infection should seek medical attention.
People living or traveling in an area where there is a viral outbreak or epidemic should isolate themselves and seek medical care if exposed to infection.
People with compromised immune systems, such as those with HIV or taking cancer medications, should always seek medical care for suspected viral infections.