What is Cytomegalovirus (CMV)?
Cytomegalovirus, or CMV, is a common virus that is part of the herpesvirus family. It can cause a range of symptoms, from no symptoms at all to severe health issues in patients with weakened immune systems or those with a congenital (present from birth) CMV disease.
CMV often infects and is associated with the salivary glands. Healthy individuals infected with CMV might not show any symptoms at all. However, it can be dangerous and even fatal for those with weakened immune systems. It can also cause severe health problems or even death in babies who are infected before they are born, which we call congenital CMV infection. After infecting someone, CMV often becomes inactive but can become active again at any time. It can eventually cause certain types of cancer, including mucoepidermoid carcinoma and possibly prostate cancer.
CMV is very common; it infects 60-70% of adults in developed countries and nearly 100% of adults in developing countries. It has a large number of genes dedicated to evading our body’s immune defenses. A lifelong burden, CMV infection requires ongoing surveillance from our immune system, and it may contribute to immune system dysfunction. Congenital CMV is one of the main infectious causes of deafness, learning difficulties, and intellectual disability.
What Causes Cytomegalovirus (CMV)?
CMV, or Cytomegalovirus, is a type of virus that has double-stranded DNA. It belongs to the herpesvirus family. Similar to other herpesviruses, once you recover from the initial infection, CMV doesn’t leave your body. Instead, it stays dormant, or “sleeping”, inside you. However, if your immune system becomes weakened or suppressed, the virus can wake up or “reactivate”.
Risk Factors and Frequency for Cytomegalovirus (CMV)
CMV, also known as cytomegalovirus, is a common virus that over half of people older than six years have been exposed to. The chance of having been exposed to this virus increases as people age. A person can catch CMV in different ways, such as through getting blood products like transfusions and organ transplantations, breastfeeding, close contact with someone shedding the virus, sexual transmission, or during birth. If a person’s immune system becomes weak, the virus can reactivate and cause serious health problems.
- Primary infection: This occurs in people who have not had CMV before. Sometimes there may be no symptoms.
- Recurrent infection: This happens when the CMV virus becomes active again in people who have had it before.
- CMV infection: This means the CMV virus is present in body fluids like urine or blood, or in body tissues.
- CMV disease: This is a CMV infection that causes general symptoms, or affects specific parts of the body.
Signs and Symptoms of Cytomegalovirus (CMV)
Cytomegalovirus (CMV) infection often doesn’t show symptoms, especially in individuals with a functioning immune system. The most common form this infection takes is mononucleosis, with symptoms including fever, skin rash, and an increased number of white blood cells. However, CMV mononucleosis differs from the usual mononucleosis caused by the Epstein-Barr Virus (EBV), as it often lacks pharyngeal exudate (a type of throat discharge) and heterophile antibodies.
Other symptoms that could appear in your blood tests include anemia, abnormal liver functions, low platelet count, positive rheumatoid factor, and positive antinuclear antibody levels. Although rare, organ complications can occur. CMV becomes a significant threat to those with weakened immune systems, such as persons with HIV or those who have undergone solid organ or bone marrow transplants, where it can cause diseases specific to certain organs like the liver, lungs, and colon.
In patients with weakened immune systems, CMV can lead to severe conditions. Here are some of the specific conditions:
- CMV hepatitis, which might result in complete liver failure
- Cytomegalovirus retinitis, which shows a “pizza pie appearance” during an eye exam
- CMV esophagitis
- Cytomegalovirus colitis
- CMV pneumonitis
- Polyradiculopathy
- Transverse myelitis
- Subacute encephalitis
Testing for Cytomegalovirus (CMV)
Usually, people with good immune health won’t need a definite diagnosis if they are suspected to have a CMV (Cytomegalovirus) infection. CMV can’t be diagnosed just by examining someone. Instead, laboratories identify the virus and this is the preferred first step in patients with suspected CMV infections. Although a histopathology diagnosis, which entails the discovery of CMV inclusion bodies, is the standard way to diagnose CMV, the preferred method to find the virus is through quantitative PCR assays.
In patients with weak immune systems, sometimes the viral load could be too low to detect, so a negative PCR doesn’t necessarily mean they don’t have a CMV infection. Serological testing provides necessary information about serostatus before an organ transplant to give an idea about the risk of CMV infection. However, this type of testing isn’t recommended for diagnosing an acute infection.
Despite low risks, CMV tests are usually run in many countries during random blood donations. Blood donations that are CMV-negative are saved for transfusions to infants and people with weak immune systems. Certain blood donation centers also maintain lists of donors who have tested as CMV-negative for special cases.
Transplant centers often test for CMV resistance nowadays. Many transplant patients have been found to have resistance to ganciclovir, a medication used in CMV treatment, which makes treatment more challenging. If a transplant patient doesn’t respond to therapeutic doses of ganciclovir or their health is rapidly worsening, it may be suspected that they’ve developed resistance to CMV.
Treatment Options for Cytomegalovirus (CMV)
Several antiviral medications, including cidofovir, foscarnet, ganciclovir, and valganciclovir, are approved to treat CMV, a type of virus.
People with strong immune systems usually experience mild or no symptoms from CMV and recover without specific treatments, other than managing the symptoms. However, in severe CMV cases, such as CMV mononucleosis, and for those with weakened immune systems, antiviral treatment is recommended.
However, these antiviral medications are not without risks. They are often associated with side effects, and the potential benefits of starting treatment should balance these risks.
Patients without CMV who receive organ transplants from donors with CMV should take preventive treatment with valganciclovir or ganciclovir. Regular blood tests are also necessary for these patients. Early treatment can prevent the establishment of potentially life-threatening infections.
What else can Cytomegalovirus (CMV) be?
The following conditions can show symptoms similar to certain others and can often be considered when a doctor is trying to make a diagnosis. These include:
- HIV (Human Immunodeficiency Virus)
- Human Herpesvirus 6 infection
- Viral hepatitis
- Epstein Barr virus
- Infectious mononucleosis (commonly known as mono)
It’s vital for healthcare professionals to think about all these conditions and carry out the correct tests to make sure the right diagnosis is given.
What to expect with Cytomegalovirus (CMV)
Most patients with CMV (Cytomegalovirus) can expect a good outcome as long as their immune system is functioning properly. With appropriate treatment, they usually recover fully, though some may experience lingering fatigue for a few months.
However, for patients who have had a marrow transplant and develop CMV pneumonia, the situation can be serious if treatment isn’t administered promptly. When treatment is delayed, these patients face a high risk of death.
Possible Complications When Diagnosed with Cytomegalovirus (CMV)
It’s very common for transplant patients to experience a relapse of CMV (Cytomegalovirus).
Preventing Cytomegalovirus (CMV)
If a patient is preparing for a transplant, it’s important to have a conversation about preventative treatment with a drug called “ganciclovir.” This talk could help keep potential health concerns at bay.
