The pancreas is an organ behind the stomach in the upper left portion of the abdomen. It is six to ten inches long and surrounded by other organs such as the small intestine, liver, and spleen. It aids in the digestion of food and regulates sugar in the blood.
What Is the Biliary Tract?
The organs and ducts are responsible for the production and storage of bile. It is a digestive fluid produced by the liver and stored in the gallbladder. Thus the biliary tract comprises the gallbladder and the bile ducts inside and outside the liver.
What Are the Viral Infections of the Biliary Tract?
In most cases, viral infections of the biliary tract are often mistaken as viral hepatitis. Viral cholangitis is less commonly discussed compared to viral hepatitis. Hepatic infections such as hepatitis A, B, C, and E are generally thought to have hepatic pathogens, but these infections can also impact the biliary tract. Systemic viral infections also lead to cholangitis. Human immunodeficiency viruses are associated with complications in the liver, which also causes cholangitis. Other systemic viruses, mostly belonging to the herpes virus family, cause hepatic diseases, also causing cholangitis (inflammation of the bile duct), and even ductopenia (reduction in the number of ducts).
In viral cholangitis, biliary tract inflammation occurs by direct invasion of the viruses or immune-mediated tissue response, causing necrosis due to secondary bacterial infections.
Among the hepatic viruses, hepatitis C is most frequently associated with cholangitis. In hepatitis B and C, the lymphocytic cholangitis duct damage is reversible and does not influence the course of the disease or disrupt the response to the therapy. Hepatitis A and E cause only mild forms of cholangitis.
It causes viral hepatitis with cholangitic lesions, causing intraepithelial lymphocytic infiltrations and lymphoid aggregates without ductal damage. These virus-associated cholangitic lesions are reversible and do not lead to permanent destruction or ductopenia. Despite this, structural damage, including diverticulum formation, is evident in these lesions. It is associated with fewer cholangiocytes in most cases.
In hepatitis B infections, the pathological lesions are not distinguished from those with viral hepatitis C infections. Twenty-five percent of hepatitis B biopsy shows lymphocytic portal aggregates, and less than ten percent reveal damage to the bile ducts.
These variants of hepatitis do not lead to chronic hepatitis. Canalicular cholestasis is seen in these infections but secondary to impairment of bile flow without anatomic or morphological correlations.
What Is the Relationship Between Cholangitis and Systemic Viruses?
Cholangitis related to HIV, which is otherwise termed AIDS (Acquired immunodeficiency syndrome) related to sclerosing cholangitis, occurs in the later stages of AIDS. Sixty percent of these cases can be due to infections, while the other forty percent occur without a specific cause. Many viruses cause cholangitis in AIDS patients, which include:
Reovirus type 3.
Of the above infectious agents, Cytomegalovirus and Cryptosporidium are the most commonly reported pathogens. Another pathogenic mechanism would be the occurrence of opportunistic microorganisms which directly produce biliary lesions. These lesions can also develop due to immune deficiency and direct cytopathic effects of this virus on the biliary tract mucosa. Inflammation of the liver is very commonly seen in patients with AIDS; biliary disease is not that common earlier but is increasingly becoming common in the present. The changes in the biliary tract include,
Common Bile Duct Papillary Stenosis: It is a condition that occurs when the valve present in the bile duct gets disturbed.
Sclerosing Cholangitis: It is a disease of bile ducts. These ducts carry the digestive liquid called bile from the liver into the small intestine. It also causes scars within the bile ducts.
Long Hepatic Bile Duct Strictures: These occur when the bile duct becomes narrower. A narrowed bile duct makes it difficult for the bile to pass through the small intestine, which can cause the accumulation of bile inside it.
The clinical findings include the following:
Abdominal Pain: Patients can experience pain in the abdomen since during AIDS, the immunity of the patient is low which can lead to painful abdominal symptoms such as abdominal cramps and inflammation.
Cholestasis Without Jaundice: This is a common clinical finding in such patients since there are alterations in the excretion of bilirubin. The patient may additionally show signs of pruritus.
Intestinal Cryptosporidiosis: An infection causes diarrhea caused by a parasite. Most people get this parasite after swallowing food or water contaminated with stool. This happens when swallowing water while swimming. People can also get infected when someone comes in contact with things or surfaces contaminated with stool. It can also spread from one person to another.
Radiographic Changes: Theseare more prominent than histological changes in AIDS cholangiopathy. The possibility of primary HIV cholangitis remains unconfirmed.
Viral Diseases in Immunocompetent Patients: The histology shows hepatocellular damage and bile duct damage. In congenital cytomegalovirus hepatitis, ductal damage and proliferation can be seen. The histological changes can resemble biliary atresia (a blockage in the tubes carrying bile from the liver to the gallbladder), including reovirus type 3 and rotavirus.
What Are the Viral Infections That Can Affect the Pancreas?
Acute pancreatitis is an inflammatory disease that affects the exocrine part of pancreatic parenchyma. It ranges from a mild self-limiting acute form to a more severe and rapidly fatal form which is also called necrotizing pancreatitis. It may also extend beyond the pancreatic tissues, which is usually associated with systemic inflammatory response, which, if not treated properly, can end up in multiorgan failure.
What Are the Etiology of Acute Pancreatitis?
The presence of gallstones and alcoholism are the two most common etiological factors of acute pancreatitis. Cholelithiasis is reported in forty to seventy percent of cases, while alcoholism is seen in twenty-five to thirty-five percent of cases. Almost ten percent of the cases are caused by other factors such as bacteria, parasites, and viruses.
What Are the Infectious Causes of Acute Pancreatitis?
Various infectious microorganisms can cause infectious pancreatitisincludes
Among the above-mentioned types of hepatitis viruses, hepatitis B is the most common type of virus that can potentially cause acute pancreatitis, mostly in post-transplantation patients. Immunosuppressive therapy in post-transplant patients plays a vital role in the development of acute pancreatitis. In a study that had twenty-seven HBsAg carriers who underwent liver transplantation, four suffered from acute pancreatitis post-transplantation. This diagnosis was made possible by detecting HBsAg in pancreatic cells and juice. Some studies have also reported acute pancreatitis, which occurs due to the hepatitis A and E viruses.
Another virus that is associated with acute pancreatitis is the coxsackie B virus, in which the patients get symptoms of acute pancreatitis, and it was identified by immunohistochemistry and serologic tests (antibodies against viral antigens). Recently different types of Coxsackievirus B4 have been found to cause acute and chronic pancreatitis mainly due to different immune-mediated reactions.
Cytomegalovirus associated with pancreatitis is not common. A case report made in the year 2014 by Chan et al. described otherwise healthy individuals with a history of acute viral infection developed hepatitis and pancreatitis at later stages. A positive polymerase chain reaction confirmed it, and the patient was administered ganciclovir which caused clinical and laboratory recovery. Cytomegalovirus infection was confirmed by a positive polymerase chain reaction, and the patient was given ganciclovir which improved the condition of the patient.
What Is the Association Between Acute Pancreatitis and HIV Patients?
In HIV infection, acute pancreatitis is a well-known complication. The incidence rises to forty percent among HIV-positive patients compared to just two percent in the general population. It can be caused either by the direct effect of the virus on the pancreatic tissue or by antiretroviral drug regimes such as nucleoside reverse transcriptase inhibitors which can induce hypertriglyceridemia, causing acute pancreatitis.
How Is Herpes Simplex Virus Associated With Acute Pancreatitis?
Herpes simplex virus is an enveloped double-stranded DNA virus that causes infection of the mucosal surfaces. It is transmitted through oral contact and causes infection in and around the mouth. Both oral and genital herpes are mostly not symptomatic but can cause painful blisters or ulcers at the site of infection. The incubation period for oral infections ranges between one to twenty-six days, and the lesion persists for one to eight days. There have been only a few cases of herpes simplex virus causing acute pancreatitis. The herpes simplex virus DNA was detected in the pancreas.
Mumps and Herpes Simplex Virus:
The first reported case of mumps as a causing factor for acute pancreatitis was observed in 1905 when Lemoine described a patient with an illness being present with mumps with symptoms of acute pancreatitis. It is a type of paramyxovirus that causes parotitis and orchitis ( inflammation of one or both testicles). It presents with abdominal pain and diarrhea. The incidence rate of mumps among patients with acute pancreatitis was about 5.1 percent who got hospitalized. The use of MMR (measles mumps and rubella vaccine) minimized the occurrence of virus-associated acute pancreatitis.
Thus, the cause of viral infections can be identified by proper diagnosis. With the advancements in technology, proper investigations need to be performed to exclude other causes of damage done to the pancreas and biliary tract. The current research has only provided the causative agents of the damage caused to the organs. More research has to be done for the sake of diagnosis and management of the damage caused to the pancreas and biliary tract by viruses.