What Is Cytomegalovirus Colitis?
Cytomegalovirus colitis is an infection of the intestine, and the cause of the infection is the virus named Cytomegalovirus, which is a herpes-type virus. Cytomegalovirus infects the person in three types of patterns:
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Primary Infection - In this case, the patient who is infected with the virus never had prior exposure to this virus. This infection occurs either by transfer of tissue or blood from a person with the latent virus or by coming in contact with a patient who is actively infected with the virus.
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Reactivation - It occurs in patients who are positive for the latent virus when their immune systems are compromised.
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Superinfection - In this case, the cytomegalovirus infection is from the latent donor cells and not from recipient cells, as it occurs when the seropositive person receives latently infected cells from another seropositive patient.
Irrespective of the pattern of the infection, an active infection results in a latent state where the Cytomegalovirus stays in the host tissues indefinitely. The latent virus reactivation can happen when the host’s T-cells response becomes compromised by the disease or for any other reason.
Cytomegalovirus can cause other infections like infections at the back of the eye, lung infections, and infections of a baby while still in the womb. Cytomegalovirus infection usually affects the whole body, even if only gastrointestinal symptoms are present.
What Is the Cause of Cytomegalovirus Colitis?
The cause of the infection is Cytomegalovirus, which is a double-stranded DNA (deoxyribonucleic acid) virus. It is a member of the Herpesviridae family. The other viruses of the same family are Herpes simplex virus 1 & 2, Varicella-zoster virus, and Epstein-Barr virus. Infection with the Cytomegalovirus is common. It can be spread through respiratory droplets, saliva, sexual contact, urine, and blood transfusions. In people with a weak immune system or those who are immunocompromised, the severity of this infection is more. A weak immune system can be because of the following:
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HIV-AIDS (human immunodeficiency virus - acquired immunodeficiency syndrome).
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Crohn's disease or ulcerative colitis (inflammatory bowel diseases that affect the innermost lining of the large intestine and bowel).
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After or during an organ transplant or bone marrow.
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Chemotherapy (anti-cancer drug treatment) treatment for cancer.
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Hemodialysis (a treatment method for kidney failure in which a machine filters wastes, salts, and fluid from the blood).
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Steroid therapy or therapy with other immunosuppressive medications.
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Neoplasia (abnormal, uncontrolled growth of cells causing tumors).
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Blood transfusions.
What Are the Signs and Symptoms of Cytomegalovirus Colitis?
Immunocompromised patients suffering from cytomegalovirus colitis usually do not show any signs or symptoms. In some patients, the following symptoms can be seen, which are non-specific:
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Frequent loose and watery stools (diarrhea).
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Increased body temperature (fever).
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Feeling sick (malaise).
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Pain in the abdomen.
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Rectal bleeding.
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Loss of appetite (anorexia).
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Weight loss.
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Swollen belly (distention).
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Aggravated symptoms of inflammatory bowel disease.
How to Diagnose Cytomegalovirus Colitis?
The following tests are recommended by the doctor:
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Physical Examination - In the early stages of the condition, abdominal signs are usually not present. Tenderness may develop in the large intestine due to the involvement of the bowel. Increased body temperature and peritoneal signs may be present.
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Serological Testing - Cytomegalovirus IgG (immunoglobulin G) test is done to verify an earlier exposure to Cytomegalovirus. This test has no diagnostic value for the diagnosis of cytomegalovirus colitis. A Cytomegalovirus IgM (immunoglobulin M) test is done to confirm an acute systemic infection with Cytomegalovirus, and this test also does not help with the diagnosis of cytomegalovirus colitis. Cytomegalovirus antigenemia assay is helpful with the diagnosis of the condition and also helps in predicting the clinical outcomes of cytomegalovirus colitis.
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Endoscopic Biopsy - An important endoscopic finding in cytomegalovirus colitis is the presence of well-defined ulcerations with a punched-out appearance. This finding is seen in 70 % to 80 % of the patients. The gold standard for the identification of cytomegalovirus colitis is cytomegalovirus-specific immunohistochemistry in tissue biopsies. The “owl eye” appearance in the H (hematoxylin) and E (eosin) stained tissue sections is the identifying feature of cytomegalovirus colitis and is highly specific for the Cytomegalovirus.
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Real-time PCR Cytomegalovirus DNA Quantification - This test is effective in only 50 % of people with cytomegalovirus colitis. Along with this test, the findings of the endoscopy are helpful in making the diagnosis of cytomegalovirus colitis.
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Cytomegalovirus Culture - This test will help in confirmation of the presence of the Cytomegalovirus in the body. It is highly sensitive and specific toward the diagnosis of the condition. But it is time-consuming, and the results of this test are delayed, which interferes with the timely treatment of cytomegalovirus colitis.
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Imaging Studies - These may show thickening of the bowel wall, mucosal ulcerations, and narrow lumen.
What Are the Complications of Cytomegalovirus Colitis?
The complications of cytomegalovirus colitis include the following:
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Toxic Megacolon and Necrotizing Colitis - Toxic megacolon is a life-threatening condition of the large intestine characterized by abnormal widening of the lumen. Necrotizing colitis is a condition that affects premature babies and is characterized by inflamed intestinal tissue.
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Perforations - It is a hole that develops in the wall of the intestine and is a serious condition that requires immediate treatment.
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Pseudomembrane Colitis - Pseudomembrane colitis is the severe inflammation of the large intestine’s inner lining. The pseudomembrane is a false membrane (a thin layer) seen as a thin yellowish-white membrane.
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Sepsis - It is a life-threatening complication of an infection. It occurs when chemicals get released into the bloodstream to fight infection.
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Peritonitis - It is the inflammation of the abdominal wall lining. It is often infectious and deadly.
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Death - Severe cases of cytomegalovirus colitis can be fatal and result in death.
What Is the Differential Diagnosis of Cytomegalovirus Colitis?
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Inflammatory Bowel Disease - It is the term used for disorders that are characterized by chronic inflammation of the digestive tract.
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Bacterial Gastroenteritis - It is an infection of the digestive tract caused by bacteria. The common symptoms include vomiting. Nausea, pain in the abdomen, abdominal cramps, fever, and diarrhea.
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Crohn’s Disease - It is a type of inflammatory bowel disease that affects the lining of the gastrointestinal tract. The inflammation usually spreads to the deeper layers of the bowel.
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Ulcerative Colitis - It is the inflammation of the gastrointestinal tract that is usually limited to the innermost lining of the large intestine. It can often lead to colon cancer.
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Celiac Disease - It is triggered by eating gluten, and it is an autoimmune disorder.
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Toxic Megacolon - It is a condition with widened parts of the colon that pushes toxic substances throughout the body. It is a life-threatening condition.
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Colorectal Cancer - It is the malignant overgrowth of cells of the colon and rectum.
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Graft-Versus-Host Disease - It is a condition that occurs at the time of transplant when the donor cells attack the host. The severity of the condition varies from mild to severe.
What Are the Treatment Options for Cytomegalovirus Colitis?
The main focus of the treatment procedure is to control the infection and relieve the patient’s symptoms.
Medication: Antiviral medicines prescribed by doctors for cytomegalovirus colitis, such as Ganciclovir, Foscarnet, and Valganciclovir. These medicines can be given intravenously and sometimes orally for weeks. These medicines are not given to immunocompetent patients because of the side effects of antivirals. The treatment with these drugs makes no significant difference in the patient’s outcomes as the symptoms in these patients go away without the treatment.
Ganciclovir has several side effects like hepatotoxicity (liver damage due to chemicals and medications), nephrotoxicity (kidney damage due to medicines), myelosuppression (decreased bone marrow activity), central nervous system disorder, and decreased white blood cell count. Ganciclovir is effective in treating cytomegalovirus in bone marrow transplant patients. Foscarnet can also have side effects like kidney problems.
In cases where these medicines are ineffective, a medicine called cytomegalovirus hyperimmune globulin may be used. This is a long-term therapy. Other medicines can be given during the treatment procedure are painkillers (analgesics) and medicines to prevent diarrhea or reduce it. Nutritional supplements may be given intravenously to treat loss of muscle due to cytomegalovirus colitis.
Conclusion:
Patients with organ transplantation are at greater risk of getting infected with this virus. Oral administration of Ganciclovir and Valganciclovir before the transplantation can decrease the chances of getting a new infection with cytomegalovirus or reactivating an old infection. Patients with HIV-AIDS who are treated with highly active antiretroviral therapy are less prone to getting infected with Cytomegalovirus.
