CMV infection after transplant

Cytomegalovirus, or CMV, is an enveloped double-stranded
DNA virus that belongs to the herpesviridae family. It’s one of the most common viruses to cause
severe infection in individuals undergoing transplantation of bone marrow or solid organs
like the liver or kidney. It can affect almost every organ in the body
resulting in encephalitis, retinitis, pneumonia, hepatitis, gastroenteritis, and of course,
transplant rejection. In the post-transplantation period, the recipient
is usually given immunosuppressive medication in order to prevent their immune system from
recognizing the transplanted tissue as foreign and causing rejection. However, one major disadvantage of this approach
is that the weakened immune system is unable to protect the body against pathogens like
CMV. CMV can be transmitted through blood and other
body fluids like saliva, genital secretions, and urine of an infected person; or from the
transplanted organ itself! During the primary infection, the virus usually
invades the epithelial cells, like those that make up the oral, GI, or urinary mucosa; and
starts to multiply. CMV damages the infected cells by breaking
down the cytoskeletons which maintain the cell structure. That results in enlarged cells with intranuclear
viral inclusion bodies, giving it the typical owl’s eye appearance. CMV also infects monocytes in the blood and
sets up a latent infection, which means that the virus remains dormant for long periods
of time. The dormant virus can reactivate at times
when the immune system weakens, causing disease. Most of the time primary infection occurs
years before the transplant with resultant reactivation of the virus during immunosuppressive
therapy. In about 25% of transplants primary infection
occurs which is usually much more severe compared to reactivation. In either case, the virus can spread throughout
the body, damaging various organs. The transplanted organ is almost always affected. This is because viral infected cells attract
an army of immune cells to the site, which in the process of killing the virus also recognise
the foreign transplanted cells and may attack them, causing collateral damage. If it spreads to the liver, it can cause viral
hepatitis, which is the inflammation of the liver. If the virus moves into the lower respiratory
system, it can cause pneumonia. It can also affect epithelial cells of the
GI tract, particularly those of the esophagus and large intestine, causing gastroenteritis. In rare cases, CMV can also affect the retina
causing retinitis, and the brain causing encephalitis. Symptoms usually begin 1 to 4 months after
the organ transplantation in the absence of antiviral prophylaxis. In the setting of prophylaxis the onset, when
it occurs, is usually within 6 months of discontinuation of prophylaxis. Depending on the organ transplanted, symptoms,
when they occur are generally accompanied by fever and malaise. Pneumonia can cause symptoms of cough and
shortness of breath. Gastrointestinal symptoms include pain and
difficulty while swallowing, abdominal pain, nausea, vomiting, and diarrhea. In addition, hepatitis can cause jaundice. Retinitis presents with blurring of vision,
dark spots in the visual field called scotomas, or even total blindness. Encephalitis presents with symptoms like altered
mental status, seizures, and weakness. Diagnosis of CMV infections involves isolation
of the virus from tissues and body fluids; polymerase chain reaction, or PCR, to detect
viral DNA, and serological tests like immunofluorescence assays to detect CMV specific antibodies in
the blood. Increased CMV-IgM titer may indicate acute
infection, and increased CMV-IgG titer indicates past infection. Specific DNA studies are more sensitive and
specific than antibody studies. As of now, there is no cure for CMV infections,
but they can be treated with the help of antiviral medications like ganciclovir, valganciclovir,
and foscarnet. Also, CMV IVIG, or intravenous immunoglobulin,
which contains anti-cytomegalovirus antibodies, can be given to help boost the immune response. Now, in high-risk individuals, like those
with a previous history of CMV infection, prophylactic antiviral therapy can be given
after the transplant to prevent reactivation. All right, as a quick recap… Cytomegalovirus, or CMV, is one of the most
common viruses to cause severe infection in transplant recipients receiving immunosuppressive
medication. It can affect almost every organ in the body
resulting in encephalitis, retinitis, pneumonia, hepatitis, gastroenteritis, and transplant
rejection. Symptoms vary based on the organ affected. CMV is diagnosed with the help of PCR and
serological testing of tissues and body fluid, and treated using antiviral medications like
ganciclovir, valganciclovir, and foscarnet; and CMV IVIG.

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