Cytomegalovirus

Definition
Cytomegalovirus (say: si-toe-meg-ah-low-vi-russ), or CMV, is a very common virus. It  is a viral genus of the viral group known as Herpesviridae or herpesviruses. It is typically abbreviated as CMV: The species that infects humans it is commonly known as human CMV (HCMV) or human herpesvirus-5 (HHV-5), and is the best studied of all cytomegoloviruses. Within Herpesviridae, CMV belongs to the Betaherpesvirinae subfamily, which also includes the genera Muromegalovirus and Roseolovirus. It is related to other herpesviruses within the subfamilies of Alphaherpesvirinae that includes herpes simplex viruses (HSV)-1 and -2 and varicella-zoster virus (VZV), and the Gammaherpesvirinae subfamily that includes Epstein-Barr virus. All herpesviruses share a characteristic ability to remain latent within the body over long periods. Although they may be found throughout the body, CMV infections are frequently associated with the salivary glands in humans and other mammals. Other CMV viruses are found in several mammal species, but species isolated from animals differ from HCMV in terms of genomic structure, and have not been reported to cause human disease.

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People are usually infected by the time they are 2 years old or during their teenage years and carry the virus for life (usually in a dormant or inactive state). The majority of adults carry the virus by the time they are 40 years of age.

Many people are infected with CMV and don’t even know it because the virus rarely causes symptoms and usually does not cause long-term problems.

However, CMV can cause problems in people who have weak immune systems and in a newborn if the mother gets the infection during pregnancy.

Causes:
CMV gets into body fluids, such as saliva, blood, urine, semen and breast milk. A person is able to transmit (or “shed”) the virus to others only when it is active in his or her system (not dormant). It can be spread from one person to another through sexual contact and contact with blood and other body fluids. CMV can rarely be transmitted by blood transfusion or organ transplantation. In developed countries, blood supplies are screened for CMV when they’re to be used for those at greatest risk from the infection.

 Symptoms:

Usually, CMV does not cause symptoms or only causes mild symptoms. A few people will have symptoms that are similar to mononucleosis. Symptoms of CMV can include:

•Sore throat
•Swollen lymph nodes (lymph glands)
•Fever
•Headache
•Fatigue
•Weakness
•Muscle aches
•Loss of appetite


People who have weakened immune systems due to conditions like human immunodeficiency virus (HIV) or because they received an organ transplant and are taking immunosuppressant medicines may have severe symptoms. (Immunosuppressant medicines are medicines that lower or suppress the immune system.) Symptoms of severe CMV include:
•Blindness
•Pneumonia
•Diarrhea
•Bleeding ulcers in the esophagus (windpipe) or intestines
•Inflammation of the brain (encephalitis)
•Seizures

If a pregnant woman transmits CMV to her unborn baby, miscarriage, stillbirth or death of the newborn may occur. Newborns who survive are at an increased risk for hearing loss and mental retardation. However, only 1% of newborns who are infected with CMV during pregnancy experience problems from the virus. Most are born healthy, or with only mild CMV symptoms.

Who’s affected?
In most cases, CMV is harmless, but for some people infection can have disastrous consequences.

People with weakened immune systems (because of HIV, for example) can suffer serious illness. They may experience high fever for two or three weeks, accompanied by hepatitis and jaundice.

Other serious complications include pneumonia, inflammation of the brain (encephalitis) and blindness as a result of inflammation of the retina at the back of the eye.

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CMV remains in the body for life. For those with strong immune systems, it remains inactive. If the immune system is weakened through illness or medical treatments, CMV may be reactivated, causing further medical problems and distress.

If a pregnant woman becomes infected with CMV for the first time, the virus may pass through the placenta and infect her unborn baby. If this happens early in pregnancy, the risk of miscarriage increases, as does the chance of the baby being born with malformations. For example, CMV infection in the womb is the leading cause of congenital deafness.

If the infection is contracted later in pregnancy, stillbirth and premature labour are more likely. A newborn baby may suffer severe illness shortly after birth – jaundice, enlargement of the liver and blood disorders.

Diagnosis:
CMV is diagnosed with a blood test.

CMV is more likey to cause vision problems in people who have weakened immune systems, so if you have conditions such as HIV or AIDS, your doctor may recommend that you visit an eye doctor to find out whether the virus has infected your eyes. Be sure to let your doctor know if you are having any painless blurring of your vision, “floaters” only in one eye, light flashes or areas of blindness. You should also let your doctor(s) know if you are experiencing frequent shortness of breath with flu-like symptoms, or if you are having problems hearing.

Treatment:
For otherwise healthy people, CMV usually doesn’t require treatment. If your immune system is weakened, your doctor may use one of several different medicines to treat CMV infection. However, because CMV is a virus, regular antibiotics won’t work against it. Antiviral drugs are usually prescribed, which slows the virus down (but cannot cure CMV).

If you are pregnant, your doctor may want to test you for CMV to determine if there is a risk for your unborn baby. If you do carry the virus, your doctor may suggest a test called amniocentesis, which collects a sample of the amniotic fluid for testing. It can help determine whether your unborn baby has CMV.

If you are pregnant and your baby has CMV, you doctor will likely check your baby once he or she is born for any problems or birth defects so they can be treated early. Treatable symptoms in newborns include pneumonia, hearing loss and inflammation of the eye.

Prevention:
In child care centers, as many as 70% of children ages 1 to 3 can shed the virus. Careful, frequent hand washing with soap and water may help prevent the spread of CMV.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://www.bbc.co.uk/health/physical_health/conditions/cmv1.shtml
http://familydoctor.org/online/famdocen/home/common/infections/common/viral/743.html
http://en.wikipedia.org/wiki/Cytomegalovirus
http://medippt.files.wordpress.com/2010/10/cytomegalovirus.jpg

http://health.allrefer.com/health/cmv-immunocompromised-host-cmv-cytomegalovirus.html

http://archive.microbelibrary.org/ASMOnly/Details.asp?ID=658

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