Microbiology
Summary
Cytomegalovirus (CMV), a member of the Herpesviridae family, is a DNA virus remains latent in the mononuclear cells such as lymphocytes, monocytes, and macrophages. This makes it a significant threat when a person becomes immunosuppressed. The virus can be transmitted via various mediums like blood, sexual contact, breast milk, saliva, and urine, and vertically from mother to child.
Congenital CMV is the most common fetal viral infection. Newborns affected can display a blueberry muffin rash, a symptom shared with congenital rubella. The infection can lead to hepatosplenomegaly, jaundice, sensorineural hearing loss, intracranial calcifications, ventriculomegaly and seizures. Despite such severe symptoms, around 80%-90% of affected newborns are asymptomatic. Hydrops fetalis is a risk of congenital CMV during the first trimester. CMV is a significant concern among organ transplant recipients and immunocompromised individuals. Immunocompromised patients, especially those with a CD4+ count of less than 50, face heightened risks of CMV infections. Clinically, these patients may exhibit CMV retinitisÑoften likened to a "pizza pie" appearance on retinal examinationÑor esophagitis characterized by specific esophageal ulcerations. Another diagnostic hallmark of CMV is the presence of "owl's eye" inclusions in infected cells. When it comes to treatment, strains harboring the UL97 gene mutation resist ganciclovir, necessitating the use of foscarnet. However, for strains without this mutation, ganciclovir remains effective. Lastly, while CMV infections can mimic symptoms like those seen in Epstein-Barr virus infections, a negative monospot test can differentiate the two.
Lesson Outline
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FAQs
Cytomegalovirus (CMV) is a type of virus belonging to the Herpesviridae family. Like other herpesviruses, CMV has the ability to remain dormant in the body for long periods of time. Primary CMV infection may be asymptomatic, but it can cause severe illness in people with weakened immune systems and in newborns infected congenitally.
Congenital CMV is a condition that arises when the virus is transmitted from a pregnant mother to the fetus. This can result in serious complications including sensory neural hearing loss, intellectual disability, and a characteristic "blueberry muffin" skin rash. Congenital CMV is a significant cause of disability in children.
Complications such as CMV pneumonia and CMV retinitis are more likely to occur in immunosuppressed individuals - those with weakened immune systems. This includes people with conditions like AIDS or HIV, or those who have undergone organ transplantation. In these patients, CMV can cause severe and potentially life-threatening complications.
The antiviral drugs ganciclovir and foscarnet are commonly used to treat CMV infections. They can help control CMV disease in immunocompromised patients or can sometimes be used in treating severe congenital CMV. These drugs work by inhibiting the replication of the virus. However, they can't completely eliminate the virus and have potential side effects, so use is usually reserved for severe or life-threatening cases.
CMV can cause an illness with symptoms very similar to mononucleosis, including fatigue, fever, and swollen lymph nodes. However, mononucleosis is most often caused by the Epstein-Barr virus, not CMV, and the monospot test specifically detects antibodies to the Epstein-Barr virus. Therefore, a patient with a CMV infection could have mononucleosis-like symptoms but test negative on the monospot test.
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