Viral Enteric & Hepatic Infections

The enteric viruses we'll learn about are naked capsids that can withstand harsh stomach acids. When symptomatic, illness is characterized by diarrhea and vomiting. Outcomes are often worse for children and infants, due to malnutrition and dehydration stemming from fluid and electrolyte loss. The causative viruses are transmitted via the fecal/oral route. For a list of bacterial pathogens that induce enteric illnesses, see here. Hepatic viruses cause tissue damage and trigger inflammatory responses that produce the symptoms of infection. Norovirus is a leading cause of gastroenteritis in all age groups in the United States; outbreaks have been associated with contaminated shellfish. Adenovirus accounts for approximately 15% of hospitalized gastroenteritis cases, especially in infants. Recall that adenovirus also causes respiratory and ocular infections. Astrovirus causes mild, watery diarrhea, most commonly in children. However, extra-intestinal infections can occur in immune-compromised patients; some viral genotypes, for example, have been associated with central nervous system infections. Rotavirus is the leading cause of severe diarrhea worldwide in children under five years old; in premature neonates, rotavirus can manifest as necrotizing enterocolitis or hemorrhagic gastroenteritis. Because of the high morbidity and mortality associated with rotavirus, vaccination is recommended for all infants. Cytomegalovirus (CMV) and Epstein-Barr Virus are associated with gastroenteritis in immune compromised patients, particularly AIDS patients and transplant recipients. Transmission: contaminated food and water. Acute gastroenteritis. – Vomiting and diarrhea. – Other symptoms include possible fever, nausea, abdominal pain or cramping, and myalgia and malaise. Treatment Rehydration and electrolyte therapy are common treatments. Hepatitis is characterized by inflammation of the liver. Acute hepatitis = Inflammation that lasts less than 6 months. Chronic hepatitis = Inflammation that lasts 6 months or longer. Fulminant liver failure: In some cases, hepatitis can lead to fulminant liver failure; write that this is characterized by rapid, acute livery injury with hepatic encephalopathy. Prevention: Vaccine availability varies for the hepatitis viruses, and there is no vaccine for Hepatitis C virus due to its heterogeneous nature. Acute hepatitis Hepatitis viruses A, B, C, D, and E can cause acute hepatitis. Jaundice, nausea and vomiting, abdominal pain, dark urine, and joint pain, as well as low or no appetite and fatigue. Liver failure is possible with acute hepatitis, but rare. – Ballooning degeneration: hepatocytes are unusually large, with a "whispy" look – Spotty necrosis throughout the liver tissue – Mononuclear cell infiltrate – Councilman bodies, which are shrunken, acidophilic cells. https://commons.wikimedia.org/wiki/File:Ballooning_degeneration_high_mag_cropped.jpg Hepatitis A and Hepatitis E only cause acute hepatitis, not chronic. – Both viruses are transmitted via the fecal-oral route, often via contaminated water. – No carrier state for these Hepatitis viruses. – Both typically cause mild and self-limiting acute hepatitis; fulminant liver failure is possible but rare. Important exception is that Hepatitis E infection has high mortality rates in pregnant women, especially during the third trimester. Chronic hepatitis Caused by Hepatitis B, Hepatitis D, and Hepatitis C. Chronic infections can lead to scarring, cirrhosis, and cancer. Smoking, alcohol use, age, sex, and population seem to increase the risk of disease progression. Hepatitis viruses B, D, and C are transmitted via body fluids. Carrier states exist. Hepatitis B can be transmitted from mother to neonate during childbirth. Hepatitis C often produces extra-hepatic effects, including cryoglobulinemia vasculitis and B-cell non-Hodgkin's lymphoma, and other immune mediated and inflammation mediated diseases. Hepatitis D is often called the "Delta agent"; though infection with Hepatitis D, alone, does not produce illness, when combined with Hepatitis B, it makes infection worse and increases the risk of Fulminant liver failure. Hepatitis B often produces "ground glass" hepatocytes; the tiny grains in the cytoplasm are from viral protein accumulation. https://commons.wikimedia.org/wiki/File:Ground_glass_hepatocytes_high_mag_2.jpg Hepatitis C infection is characterized by lymphocyte aggregates and follicles, especially around the portal tracts; bile ducts are often damaged, and, steatosis (also called fatty change) can also occur. https://commons.wikimedia.org/wiki/File:Steatosis_severity_at_histopathology.jpg

• Flaviviridae
• Cytomegalovirus
• Epstein Barr Virus