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Transcript
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 • HAV – Infectious hepatitis • HBV – Serum hepatitis • HCV – Chronic hepatitis • HDV – Requires co-infection with HVB • HEV – Enteric hepatitis • 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 • 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 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 Giardiasis • Causative agent – Giardia intestinalis • Flagellated, pear shaped • Two nuclei • Exists in two forms – Feeding trophozoite – Dormant cyst » Tough chitin shell • 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 – 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 • 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 • Prevention – Filtration or boiling of water – Good hygiene practices – Sanitary disposal of feces – Safe sex • Treatment – Fluid and electrolyte replacement – Metronidazole or quinocrine Cryptosporidiosis • Causative agent – Cryptosporidium parvum • Multiplies cells of small intestine • Apicomplexan • Exists in two forms – Acid fast oocyst – Sporozoite • 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 – 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 • 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 • 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 Amebiasis • Causative agent: Entamoeba histolytica – Exists in two forms – Feeding trophozoite – Dormant cyst • 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 • 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 • Prevention – – – – Disinfection, filtration and boiling of water Sanitary disposal of feces Good hygiene practices Safe sex • Treatment – Oral rehydration – Metronidazole or iodoquinol 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 • 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 Scolex used for attachment Monoecious proglottids may be motile Complex life cycle divided between definitive and intermediate hosts – Epidemiology • Highest incidence poor rural areas • Inadequate sewage treatment • Humans live in close contact with livestock – Diagnosed by presence of proglottids in feces • Prevention – Relies on thorough cooking of meats and sewage treatment • Treatment – Niclosamide or praziquantel – May require surgical removal of worm • Pinworm Infestations – Nematode • Enterobius vermicularis • Sexually dimorphic – Signs and symptoms • perianal itching, irritability, decreased appetite – 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 • Prevention – Requires strict personal hygiene • Treatment – Pyrantel pamoate or mebendazole