Cytomegalovirus: Description, Causes and Risk Factors:
Cytomegalovirus, or CMV, is a common virus that infects most people worldwide. CMV infection is usually harmless and rarely causes illness. A healthy immune system can hold the virus in check. However, if a person's immune system is seriously weakened in any way, the virus can become active and cause CMV disease.
CMV is common worldwide. An estimated 80% of adults in the United States are infected with CMV. CMV is also the virus most often transmitted to a developing fetus before birth.
Human cytomegalovirus (HCMV) or human herpesvirus 5 (HHV-5) is a member of the Herpesviridae family, subfamily Betaherpesvirinae. HCMV can be a potential killer or a lifelong silent companion. HCMV is the largest virus in the family and is morphologically indistinguishable from other human herpesviruses.
HCMV include the ability to infect in vivo a broad spectrum of cells (fibroblasts, epithelial and endothelial cells, macrophages, muscle cells). HCMV like all herpesviruses undergoes latency and reactivation in the host. The only cells that are fully permissive for HCMV replication in vitro are human fibroblasts. In these cells, virus replication results in the formation of intranuclear and intracytoplasmic inclusion bodies. With the former full of nucleocapsids and the latter containing several dense bodies, nucleocapsids acquire the envelope from the nuclear membrane or cytoplasmic vacuoles.
When humans are infected it remains dormant in the body for the rest of their life when it is not active.
The virus spreads through bodily fluids, including saliva, blood, breast milk, semen and urine. Cytomegalovirus is human-to-human transmissible through close bodily contact (coughs and sneezes are also possible routes).
Acquired CMV is a primary CMV (first-time infection). Recurring CMV means the patient is already infected, the virus is dormant, and then becomes active due to a weak immune system. Congenital CMV infection occurs during pregnancy and affects the fetus (unborn baby).
Systemic HCMV syndrome is characterized by the following symptoms and signs: fever >38°C for at least 2 days, malaise, leukopenia, thrompocytopenia.
HCMV end-organ disease is defined by symptoms and signs of organ involvement (pulmonary, gastrointestinal, hepatic, neural or, less frequently, other organ sites) associated with either immunohistochemical or virological detection.
Age did not appear to be a risk factor for CMV infection and the association between CMV infection and gender was inconsistent. Other risk factors include bacterial pneumonia and sepsis. Corticosteroid use also considered to be a risk factor in one study.
Active infection in otherwise healthy children and adults can cause prolonged high fever, chills, severe tiredness
, a generally ill feeling, headache
, and an enlarged spleen.
People with weakened immune systems can have more serious, potentially life-threatening illnesses, with fever, pneumonia, liver infection, and anemia. Illnesses can last for weeks or months and can be fatal. In persons with HIV infection, CMV can infect the retina of the eye and cause blindness.
HCMV can cause systemic and organ infections, including the lungs,gastrointestinal tract, liver, kidney andcentral or peripheral nervous system.
Human Cytomegalovirus Infection (CMV) is a common cause of congenital infection and a leading cause of hearing loss in children. Most children with congenital CMV infection develop normally, without any permanent perceptual, cognitive, or motor deficits. SNHL (sensorineural hearing loss) is observed in approximately 10% to 15% of children with congenital CMV infection. The majority of children with CMV-related hearing loss experience delayed onset loss and continued deterioration of hearing function during childhood.
There are special laboratory tests to culture the virus, but testing requires 2 to 3 weeks and is expensive. Blood tests can help diagnose infection or determine if a person has been exposed in the past.
Doctors can diagnose a serious CMV infection by taking a culture from a person's throat, urine, blood, or other body tissues or fluid. Blood tests also can look for certain antibodies that are part of the immune system's response to a CMV infection; their presence can signal an active CMV infection. Special viral DNA-detecting tests are also sometimes used to diagnosis CMV infection.
Research is currently underway for a potential HCMV vaccine. However, there is no current cure for HCMV infection. Medications can help newborns and people with weak immune systems. Presently, HCMV infection is mostly controlled in immunocompromised patients by available antiviral drugs, yet it continues to maintain its role as the most dangerous infectious agent for the unborn infant. Thus, HCMV infection is still a major health problem, warranting strong preventive measures.
Due to the high morbidity and mortality rate associated with HCMV disease in the transplantation setting in the absence of adequate intervention, the optimal management strategy for the control of HCMV infection is the prevention of overt disease.
The above information is just informative purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.