Viral Diarrhea

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Viral Diarrhea

  1. 1. Viral Diarrhea Chris E. Forsmark, M.D. Division of Gastroenterology, Hepatology, and Nutrition
  2. 2. Virus Types <ul><li>Viral gastroenteritis </li></ul><ul><ul><li>Rotavirus </li></ul></ul><ul><ul><li>Caliciviruses </li></ul></ul><ul><ul><li>Adenovirus </li></ul></ul><ul><ul><li>Astrovirus </li></ul></ul><ul><ul><li>Others (Torovirus, coronavirus,pestivirus) </li></ul></ul><ul><li>Viral colitis </li></ul><ul><ul><li>Cytomegalovirus </li></ul></ul>
  3. 3. Magnitude of the Problem Bull WHO 1992
  4. 4. Magnitude of the Problem <ul><li>Developing countries </li></ul><ul><ul><li>2.6 episodes/child/year in children < 5 </li></ul></ul><ul><ul><li>700 million episodes/year </li></ul></ul><ul><ul><li>3-5 million deaths/year </li></ul></ul><ul><li>United States </li></ul><ul><ul><li>Approx 180,000 hospitalizations/year in children < 5 </li></ul></ul><ul><ul><li>Mortality rare </li></ul></ul>
  5. 7. Viral Gastroenteritis in Children
  6. 8. Rotavirus <ul><li>Discovered in 1973 </li></ul><ul><li>Worldwide distribution </li></ul><ul><li>All children exposed by age 4-5 </li></ul><ul><li>Double stranded RNA virus </li></ul><ul><li>Several groups (A-E vs G-P) </li></ul><ul><li>Most common cause of viral diarrhea </li></ul><ul><ul><li>35% hospitalized, 10% community </li></ul></ul>
  7. 9. Rotavirus
  8. 10. Rotavirus
  9. 11. Rotavirus
  10. 12. Rotavirus structure
  11. 13. Transmission of Rotavirus <ul><li>Fecal-oral </li></ul><ul><li>Contaminated water supplies </li></ul><ul><li>Poor hygiene </li></ul><ul><li>Food </li></ul><ul><li>Fomites </li></ul>
  12. 14. Rotavirus: Clinical Syndromes <ul><li>Childhood gastroenteritis </li></ul><ul><ul><li>Endemic in tropics </li></ul></ul><ul><ul><li>Winter in temperate zone </li></ul></ul><ul><li>Outbreaks </li></ul><ul><ul><li>Day care centers </li></ul></ul><ul><ul><li>Hospitals </li></ul></ul><ul><li>Immunocompromised adults </li></ul>
  13. 15. How does Rotavirus cause diarrhea? <ul><li>Injures intestinal epithelium </li></ul><ul><ul><li>Malabsorption </li></ul></ul><ul><li>Increases secretion by epithelium </li></ul>
  14. 16. Diarrhea Classification <ul><li>Pathophysiology </li></ul><ul><ul><li>Osmotic </li></ul></ul><ul><ul><li>Secretory </li></ul></ul><ul><ul><li>Exudation </li></ul></ul><ul><ul><li>Abnormal motility </li></ul></ul><ul><li>Duration </li></ul><ul><ul><li>Acute (< 6 weeks) </li></ul></ul><ul><ul><li>Chronic (> 6 weeks) </li></ul></ul>
  15. 20. Osmotic diarrhea <ul><li>Def: Increased amounts of poorly absorbed, osmotically active solutes in gut lumen </li></ul><ul><li>Interferes with reabsorption of water </li></ul><ul><li>Solutes are ingested </li></ul><ul><ul><li>magnesium </li></ul></ul><ul><ul><li>sorbitol </li></ul></ul><ul><ul><li>malabsorption of food (mucosal injury, lactase deficiency) </li></ul></ul>
  16. 21. Secretory diarrhea <ul><li>Excess secretion of electrolytes, fluid across mucosa </li></ul><ul><li>Usually coupled with decrease in absorption </li></ul><ul><li>Watery, high-volume diarrhea with dehydration </li></ul><ul><li>Enterotoxins: Cholera, E. coli, food poisoning, Rotavirus (?), Norwalk virus (?) </li></ul>
  17. 24. Rotavirus Clinical Syndromes <ul><li>Asymptomatic carriers </li></ul><ul><li>Diarrheal illness </li></ul><ul><ul><li>2-3 day incubation period </li></ul></ul><ul><ul><li>diarrhea, vomiting fever 3-7 days </li></ul></ul><ul><ul><li>high infectivity </li></ul></ul><ul><li>Complications </li></ul><ul><ul><li>dehydration </li></ul></ul><ul><ul><li>chronic diarrhea </li></ul></ul><ul><ul><li>dissemination </li></ul></ul><ul><ul><li>NEC </li></ul></ul>
  18. 25. Diagnosis of rotavirus <ul><li>Electron microscopy </li></ul><ul><ul><li>Small intestine </li></ul></ul><ul><ul><li>Stool </li></ul></ul><ul><li>Antigen in stool </li></ul><ul><ul><li>commercial ELISA </li></ul></ul><ul><ul><li>research PCR, nucleic acid probes </li></ul></ul>
  19. 26. Therapy for rotavirus <ul><li>Rehydration </li></ul><ul><ul><li>ORT </li></ul></ul><ul><ul><li>Intravenous </li></ul></ul><ul><li>Probiotics </li></ul><ul><ul><li>lactobacilllus GG </li></ul></ul><ul><li>Bismuth </li></ul>
  20. 27. Oral rehydration solutions
  21. 30. Prevention of Rotavirus <ul><li>Natural immunity 93% protective (sIgA) </li></ul><ul><li>Vaccination </li></ul><ul><ul><li>heterologous rotavirus (bovine, rhesus) </li></ul></ul><ul><ul><li>reassortment rotavirus (rhesus-human) </li></ul></ul><ul><ul><li>nonreplicating particles </li></ul></ul><ul><ul><li>naked DNA </li></ul></ul>
  22. 31. Calicivirus <ul><li>Norwalk virus and “Norwalk-like” </li></ul><ul><li>“ Sapporo-like” viruses </li></ul><ul><li>Vesivirus </li></ul><ul><li>Lagovirus </li></ul><ul><li>All single stranded RNA viruses </li></ul>
  23. 33. Norwalk virus
  24. 34. Norwalk virus <ul><li>“winter vomiting disease” 1968, Norwalk OH </li></ul><ul><li>Cause 40% of nonbacterial epidemics </li></ul><ul><li>Explosive epidemics </li></ul><ul><ul><li>camps, cruise ships, nursing homes </li></ul></ul><ul><li>Food borne illness </li></ul><ul><ul><li>raw shellfish </li></ul></ul>
  25. 35. Food-borne illness
  26. 36. Shellfish-borne infections
  27. 37. Norwalk virus: Clinical Features <ul><li>24-48 hour incubation period </li></ul><ul><li>vomiting prominent </li></ul><ul><li>diarrhea 1-3 days </li></ul><ul><li>less severe than rotavirus </li></ul><ul><li>affects all ages </li></ul><ul><ul><li>antibodies in 60% of adults </li></ul></ul><ul><li>complications rare </li></ul><ul><ul><li>immunocompromised </li></ul></ul>
  28. 38. How does Norwalk virus cause diarrhea? <ul><li>Infection affects proximal small bowel </li></ul><ul><li>Patchy mucosal injury </li></ul><ul><li>Malabsorption </li></ul><ul><li>? Excess secretion </li></ul>
  29. 39. Norwalk virus Before ingestion 2 days 6 days
  30. 40. Diagnosis of Norwalk virus <ul><li>Clinical diagnosis (exclude rotavirus) </li></ul><ul><li>Immune EM </li></ul><ul><li>Serology of antibody response </li></ul><ul><li>enzyme immunoassays </li></ul><ul><li>RT-PCR </li></ul><ul><li>oligonucleotide probes </li></ul>
  31. 41. Treatment of Norwalk virus <ul><li>Rehydration </li></ul><ul><li>Supportive measures </li></ul><ul><ul><li>bismuth </li></ul></ul><ul><ul><li>antidiarrheals (Lomotil, Immodium) </li></ul></ul>
  32. 42. Other viruses causing gastroenteritis <ul><li>Astrovirus </li></ul><ul><ul><li>children, outbreaks </li></ul></ul><ul><li>Adenovirus </li></ul><ul><ul><li>children, prolonged course </li></ul></ul><ul><li>Torovirus </li></ul><ul><ul><li>children, bovine pathogen </li></ul></ul>
  33. 43. Cytomegalovirus <ul><li>Herpesvirus </li></ul><ul><li>Immune competent </li></ul><ul><ul><li>Mononucleosis-type syndrome </li></ul></ul><ul><li>Immunocompromised </li></ul><ul><ul><li>retinitis </li></ul></ul><ul><ul><li>hepatitis </li></ul></ul><ul><ul><li>gastrointestinal involvement (colon) </li></ul></ul>
  34. 45. Cytomegalovirus colitis

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