Hepatitis

1. Hepatitis • Inflammation of liver • Autoimmune disease, alcohol/drug abuse, genetic disorders, viral infection • Five viruses cause hepatitis • Hepatitis A virus (HAV); HBV, HCV, HDV, HEV

2. HAV • Infectious hepatitis • HBV • Serum hepatitis • HCV • Chronic hepatitis • HDV • Requires co-infection with HVB • HEV • Enteric hepatitis

3. Signs and symptoms: • Jaundice, nausea, vomiting, fatigue, fever, weight loss • Complications from chronic infection: • Cirrhosis; liver failure, liver cancer and death • Most damage is caused by host defenses

4. Transmission • contaminated food or water; fomites and sexual contact • Treatment • Supportive care for symptom • Anti-virals or interferon may help against HVB or HVC • Passive immunotherapy • Prevention • Avoiding exposure by practicing good hygiene and protected sex or abstinence • Vaccines are available against HAV and HBV

6. Protozoal Diseases of GI Tract • Most significant human pathogens worldwide • Few are intestinal pathogens • Transmitted by fecal to oral route • Fecal contaminated water • May be zoonotic

7. Giardiasis • Causative agent • Giardia intestinalis • Flagellated, pear shaped • Two nuclei • Exists in two forms • Feeding trophozoite • Dormant cyst • Tough chitin shell

8. Signs & Symptoms • Range from mild to severe • Indigestion, nausea, vomiting, malnutrition and weight loss, severe greasy, frothy diarrhea with “rotten egg” odor and excess gas (H2S) • Symptoms usually disappear within 4 weeks • Some cases become chronic • Animals tend to be asymptomatic reservoirs

9. Cyst infective stage • Resists stomach acid • Two trophozoits per cyst • Trophozoits attach to epithelium of small intestine with adhesive disk • In severe cases, may cover entire intestinal surface

10. Epidemiology • Transmission usually fecal-oral route • May be zoonotic • Beavers, raccoons, muskrats, dogs, cats • Single stool can carry 300 million cysts • Cysts can survive in cold water up to 2 months • Chlorination often ineffective against cysts • Diagnosed by cysts or trophozoites in stool

11. Prevention • Filtration or boiling of water • Good hygiene practices • Sanitary disposal of feces • Safe sex • Treatment • Fluid and electrolyte replacement • Metronidazole or quinocrine

12. Cryptosporidiosis • Causative agent • Cryptosporidium parvum • Multiplies cells of small intestine • Apicomplexan • Exists in two forms • Acid fast oocyst • Sporozoite

13. Signs & Symptoms • Fever, headache, loss of appetite, nausea, abdominal cramps and profuse watery diarrhea • Can last for months • May be life threatening in immunocompromised individuals • Hepatatis, pancreatitis

14. Oocyst releases 4 bannana shaped sporozoites into small intestine • Sporozoites invade epithelium • Cause deformity in cells and villi • Initiates inflammatory response • Water secretion increases & nutrient absorption decreases

15. Epidemiology • Oocysts eliminated in feces • Individuals can expel organisms for up to 2 weeks after diarrhea ceases • Person-to-person spread occurs • Cysts can survive long periods in food and water • Resistant to chlorination but to small for most filters • Zoonotic with a wide host range • Diagnosed by oocysts in stool

16. Prevention • Careful monitoring of municipal water supplies • Pasteurization of drinks • Sanitary disposal of feces • Immunodeficient should avoid contact with animals and recreational water activities • Treatment • Replacement of water and electrolytes

17. Amebiasis • Causative agent: Entamoeba histolytica • Exists in two forms • Feeding trophozoite • Dormant cyst

18. 3 forms of Amebiasis: • Luminal –asymptomatic • Amebic dysentery – more severe; dysentery, colitis and ulceration of mucosal lining • Invasive extra-intestinal –necrotic lesions form in liver, lungs, spleen, kidneys and brain

19. Epidemiology • Transmission usually fecal-oral route • Cysts survive 1-2 weeks in environment • No animal reservoir • 10% of global population are carriers • 3rd leading cause of parasitic death • 50 million cases and 100,00 deaths annually • Diagnosed by cysts or trophozoites in stool

20. Prevention • Disinfection, filtration and boiling of water • Sanitary disposal of feces • Good hygiene practices • Safe sex • Treatment • Oral rehydration • Metronidazole or iodoquinol

21. Helminthic Infestations • Macroscopic, multi-cellular parasitic worms • Cestodes • Flat, segmented, monoecious • Intestinal parasites that lack complete digestive system • Nematodes • Round, un-segmented, diecious, sexually dimorphic • Complete digestive system and protective cuticle

22. Tapeworm Infestations • Cestodes • Taenia saginata – beef tapeworm • Taenia solium – pork tapeworm • Signs and symptoms • Usually asymptomatic • nausea, abdominal pain, weight loss, and diarrhea may occur • Worm may cause intestinal blockage

23. Scolex used for attachment Monoecious proglottids may be motile Complex life cycle divided between definitive and intermediate hosts

24. Epidemiology • Highest incidence poor rural areas • Inadequate sewage treatment • Humans live in close contact with livestock • Diagnosed by presence of proglottids in feces

25. Prevention • Relies on thorough cooking of meats and sewage treatment • Treatment • Niclosamide or praziquantel • May require surgical removal of worm

26. Pinworm Infestations • Nematode • Enterobius vermicularis • Sexually dimorphic • Signs and symptoms • perianal itching, irritability, decreased appetite

27. Epidemiology • Infections commonly occur in children • Most common parasitic worm in the US • Diagnosis based on microscopic id of eggs or presence of adult pinworms

28. Prevention • Requires strict personal hygiene • Treatment • Pyrantel pamoate or mebendazole