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 (H 2 S) –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 –3 rd 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. Complex life cycle divided between definitive and intermediate hosts Scolex used for attachment Monoecious proglottids may be motile

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