Cindi Chou
BIOL 230 – CRA

Disease: Cytomegalovirus (CMV) Infections

Causative Agents

Cytomegalovirus (CMV) belongs to the subfamily Betaherpesvirinae within the family Herpesviridae.  The average size of viruses within this family falls within 150nm – 200nm. CMV contains double-stranded linear DNA with a capsid (def) made up of 162 hexagonal protein capsomeres (def).  It is an enveloped virus (def).

Epidemiology

CMV is found in individuals around the world but is especially prevalent in developing countries and in areas of lower socioeconomic status.  Within the United States, 50% to 80% of adults have been infected with CMV at some point in their lives by the age of 40.  Once infected with CMV, individuals remain infected for the rest of their lives.  The actual age of infection varies from person to person.   

Less than 1% of healthy individuals die from CMV infections.  However, CMV infections may become life threatening to immunocompromised individuals, such as patients who received solid organ or bone marrow transplants, individuals infected with HIV, or individuals receiving chemotherapy.

In pregnant women, CMV is the virus that is most frequently transmitted to fetuses.  It is estimated that about 1 in 150 children are born with CMV infection and that 1 in 750 children develop permanent disabilities due to CMV infection.

Transmission

CMV is found in various bodily fluids, including urine, saliva, blood, tears, semen, vaginal fluid, and breast milk.  The chances of transmitting CMV through casual contact are very small.  The virus is spread via person-to-person contact in various ways including touching one’s eye or inside of the nose or mouth after touching the bodily fluid of an infected person, sexual contact with an infected person, through blood transfusion or organ transplantation, through the breast milk of an infected mother to a child, or when a woman becomes infected during pregnancy and the virus passes through the placenta (def) to the fetus.  In pregnant woman, the most common mode of transmission is through contact with the saliva or urine of young children.

Signs and Symptoms

CMV is a silent virus (def) and rarely causes visible symptoms in healthy individuals.  Occasionally, infected individuals will develop mild flulike symptoms or symptoms similar to that of mononucleosis (def).  These symptoms include fatigue, weakness, night sweats, fever, swollen glands, sore throat, loss of appetite, muscle aches, and joint pain or stiffness.

If an immunocompromised individual becomes infected, the symptoms can be much more severe.  In these individuals, CMV may target specific organs.  The resulting signs and symptoms include vision impairment or vision loss, hearing loss, encephalitis (def), seizures, diarrhea, and ulcerations (def) with bleeding.  

Pregnant women who become infected with CMV may not develop any visible symptoms but as previously mentioned, may pass the virus to the fetus.  The majority of newborns with congenital (def) CMV never develop symptoms.  However, some newborns show immediate symptoms at birth and others develop symptoms over time.  Some immediate signs of the infection in newborns include petechiae (def), jaundice (def), having an enlarged spleen, having an enlarged and poorly functioning liver, seizures, and small size for gestational age.  These signs and symptoms tend to only affect the child temporarily.  Symptoms of congenital CMV infection that develop over time include hearing loss, vision loss, mental disability, microcephaly (def), lack of coordination, autism, seizures, and death.  These symptoms tend to be permanent, with the most common sign being hearing loss.     

On rare occasions, CMV may cause complications in a healthy person.  Individuals may become very ill and develop symptoms closely resembling infectious mononucleosis.  Serious CMV infections may also cause complications in the liver leading to abnormal functioning in the liver and unexplained fever.  For some, the neurological system can be affected, leading to a range of symptoms, include encephalitis (def).  CMV may also cause complications in the lungs, leading to the development of pneumonitis (def).

Prevention and Treatment

The spread of CMV can be prevented by good hygiene practices.  Careful handwashing is very important.  Pregnant women should be especially careful when interacting with young children who are more likely to have CMV in their urine or saliva than older children and adults. 

Although scientists and researchers are looking for a vaccine for CMV and different methods to prevent the transmission of CMV to fetuses, there is presently no cure.  Certain drugs that have proven to be effective against CMV have serious side effects.  These drugs have not been approved for use by pregnant women.  Research studies have shown that the antiviral drug, ganciclovir (def), may be effective in preventing hearing loss in children with congenital CMV.  Glanciclovir (def) is a (def) that inhibits DNA synthesis.  However, there are many severe side effects and has only been tested in children with very severe congenital CMV symptoms. 

Bibliography

CDC. National Center for Immunization and Respiratory Diseases. Cytomegalovirus (CMV). Retrieved April 15, 2010 from http://www.cdc.gov/cmv/facts.htm

Department of Health, New York State. Cytomegalovirus (CMV). Retrieved April 15, 2010 from http://www.health.state.ny.us/diseases/communicable/cytomegalovirus/fact_sheet.htm

Mayo Clinic staff. Cytomegalovirus (CMV) Infection. May 1, 2009. MayoClinic.com. Retrieved April 16, 2010 from http://www.mayoclinic.com/health/cmv/DS00938

Wills, Todd S. Cytomegalovirus. Apr. 28, 2009. e Medicine.com.  Retrieved April 15, 2010 from http://emedicine.medscape.com/article/215702-overview

Wills, Todd S. Cytomegalovirus: Treatment & Medication. Apr. 28, 2009. e Medicine.com.  Retrieved April 15, 2010 from http://emedicine.medscape.com/article/215702-treatment