Cytomegalovirus

Pronunciation

SY-toh-MEH-guh-loh-VY-rus Cytomegalovirus, often abbreviated as CMV, is a herpesvirus that can cause infections, including pneumonia, gastroenteritis, encephalitis, retinitis especially, in immunosuppressed people.

Cytomegalovirus

Cause

The causal agent, cytomegalovirus or CMV is a member of the herpesvirus family, which includes herpes simplex virus types 1 and 2, varicella-zoster virus, and Epstein-Barr virus.

Latency

These viruses share a characteristic ability to establish lifelong latency. After initial infection, which may cause few symptoms CMV becomes latent, residing in cells without causing detectable damage or illness.

Transmission

• CMV infects people of all ages. In the United States; nearly one in three children are infected with CMV by age five. Over half of adults have been infected with CMV by age 40, most with no signs or symptoms.
• CMV is transmitted by direct contact with infectious body fluids, such as urine, saliva, blood, tears, semen, and breast milk. CMV can be transmitted sexually and through transplanted organs and blood transfusions.
• CMV can be transmitted to infants through contact with the mother’s genital secretions during delivery or through breast milk. Healthy infants and children who acquire CMV after birth generally have few, if any, symptoms or complications from the infection.
• Although the virus is not highly contagious, it has been shown to spread among household members and young children in daycare centers.

HIV and CMV

Although CMV can infect most organs of the body, HIV-infected people are most susceptible to CMV retinitis.

Dormant state

A virus that may be carried in an inactive state for life by healthy individuals.

Cytomegalovirus pneumonia

Signs and Symptoms

In some cases, infection in healthy people can cause mild illness that may include:

• Fever
• Sore throat
• Fatigue
• Lymphadenopathy Swollen glands

Cytomegalovirus infection

Mononucleosis and or hepatitis

Occasionally, CMV can cause mononucleosis or hepatitis.

Immunocompromised

• People with weakened immune systems who get CMV can have more serious symptoms affecting the eyes, lungs, liver, esophagus, stomach, and intestines.
• Babies born with CMV can have brain, liver, spleen, lung, and growth problems.
• The most common long-term health problem in babies born with congenital CMV infection is hearing loss, which may be detected soon after birth or may develop later in childhood.

CMV-infected pneumocytes

Transmission

• People with CMV may pass the virus in body fluids, such as saliva, urine, blood, tears, semen, and breast milk. CMV is spread from an infected person in the following ways:
• From direct contact with saliva or urine, especially from babies and young children
• Through sexual contact
• From breast milk to nursing infants
• Through transplanted organs and blood transfusions

Overview of diverse HCMV proteome involved in modulation of host cell controlled growth

In utero

• Infants infected in utero (congenital CMV infection) can lead to:
• Very low birth weight and premature infants
• People with compromised immune systems, such as from organ and bone marrow transplants, and people infected with human immunodeficiency virus (HIV)
• CMV can be transmitted to infants through contact with the mother’s genital secretions during delivery or through breast milk.
• Healthy infants and children who acquire CMV after birth generally have few, if any, symptoms or complications from the infection.
• Although the virus is not highly contagious, it has been shown to spread among household members and young children in daycare centers.

Pregnant Women and CMV

• In the United States, nearly half of women have been infected with CMV before their first pregnancy. Of women who have never had a CMV infection, it is estimated that 1 to 4% of them will be infected during pregnancy.
• A woman who has a primary CMV infection during pregnancy is more likely to pass CMV to her fetus than a woman who has a subsequent infection during pregnancy. However, in the United States, 50 to 75% of congenital CMV infections occur among infants born to mothers who were infected with CMV before they became pregnant.
• Routine screening for primary CMV infection during pregnancy is not recommended in the United States for several reasons:
• Most laboratory tests currently available to identify a first-time infection can be difficult to interpret,
• Current tests cannot predict if the fetus may become infected or harmed by infection,
• The lack of a proven treatment to prevent or treat infection of the fetus reduces the potential benefits of prenatal screening.
• Very Low Birth Weight and Premature Infants
• There are no recommendations against breastfeeding by mothers who are CMV-seropositive. However, infants born <30 weeks gestational age and <1500g who acquire CMV from breast milk may be at risk of developing a late-onset sepsis-like syndrome. The potential benefits of human milk versus the risk of CMV transmission should be considered when making a decision about the breastfeeding of very premature babies by mothers known to be CMV-seropositive.

CMV schema

CMV and hearing loss

• Hearing loss is common in babies with congenital CMV, even those without symptoms at birth.
• Cytomegalovirus, or CMV, is the most common infectious cause of birth defects in the United States. About 1 out of 200 babies is born with congenital CMV.
• One out of 5 babies with congenital CMV will have symptoms or long-term health problems, such as hearing loss.
• Hearing loss may progress from mild to severe during the first two years of life, which is a critical period for language learning.
• Over time, hearing loss can affect your child’s ability to develop communication, language, and social skills.

National Cytomegalovirus (CMV) Awareness Month

• National Cytomegalovirus (CMV) Awareness Month is an annual observance held in June to increase awareness of CMV, the most common infectious cause of birth defects.
• CMV is the most common infectious cause of birth defects in the United States.
• About 1 out of 5 babies with congenital CMV infection will have birth defects or other long-term health problems, such as hearing loss. 
• In 2011, Congress passed a resolution naming June “National CMW Awareness Month.”

Cytomegalovirus infection of kidney

Diagnosis

• Blood tests can be used to diagnose CMV infection in adults who have symptoms.
• However, blood is not the best fluid to test newborns with suspected CMV infection.
• Tests of saliva or urine are preferred for newborns.

Treatment

• Healthy people who are infected with CMV usually do not require medical treatment.
• Medications are available to treat CMV infection in people who have weakened immune systems and babies with signs of congenital CMV.
• For babies with signs of congenital CMV infection at birth, antiviral medications, primarily valganciclovir, may improve hearing and developmental outcomes.
• Valganciclovir can have serious side effects and has only been studied in babies with signs of congenital CMV infection.
• There is limited information on the effectiveness of valganciclovir to treat infants with hearing loss alone.

Ganciclovir

• ===Treatment of congenital CMV infection===
• For infants with signs of congenital CMV disease at birth, antiviral medications, such as ganciclovir or valganciclovir, may improve hearing and developmental outcomes.
• Ganciclovir can have serious side effects and has only been studied in infants with symptomatic congenital CMV disease.
• There is limited information on the effectiveness of ganciclovir or valganciclovir to treat infants with hearing loss alone.
• Any infant diagnosed with congenital CMV infection should have regular hearing and vision tests. 
• Most infants with congenital CMV grow up healthy.
• Early detection and intervention for children with hearing and vision problems may improve outcomes

Prevention

CMV is common in children and can be found in especially high amounts in young children’s saliva and urine. Avoiding contact with saliva and urine from young children might reduce the risk of CMV infection. Healthcare providers should follow standard precautions. Vaccines are still in the research and development stage.

Cytomegalovirus Resources
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