The Gastrointestinal Tract – Flashcards

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What are the 8 main segments of the gastrointestinal tract?
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mouth esophagus stomach small intestine large intestine rectum anus
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What are the 4 accessory organs?
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salivary glands liver gallbladder pancreas
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Defenses against a heavy load of microorganisms:
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Heavy load of mucus Secretory IgA Peristalsis (movement of intestines) keeps microbes moving Saliva: lysozyme, lactoferrin Stomach: extremely low pH Bile is antimicrobial GALT (gut-associated lymphoid tissue)
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Microbial composition _ between individuals. Oral cavity: _ species of bacteria. Esophagus and stomach: _ species of organisms. Large intestine: _ microbes per gram of contents; where most microbes are found. Accessory organs: _ of resident organisms; liver, gallbladder, salivary glands, pancreas.
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varies 600 200 10^11 free
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Functions of normal gut biota: (3)
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Protective function Aid digestion and provide nutrients A diverse gut microbiome is associated with health
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defenses of the oral cavity
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saliva secretory IgA lysozyme tonsils adenoids
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defenses of the rest of the gastrointestinal tract
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GALT lymphoid tissue peyer's patches appendix secretory IgA rich normal biota
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What are the 2 types of diseases of the gastrointestinal tract?
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nonhelminthic helminthic
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Nonhelminthic diseases of the gastrointestinal tract: (7)
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Teeth and Gums Salivary Glands Gastric Infections Acute Diarrhea with or without vomiting Acute Diarrhea with vomiting Chronic Diarrhea Hepatitis
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not lasting longer than 2 weeks
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acute
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lasting longer than 2 weeks
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chronic
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Helminthic disease of the Gastrointestinal tract (8)
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Whipworm Pinworm Tapeworm Giant intestinal roundworm Hookworm Liver flukes Trichinosis Schistosomiasis
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Helminthic infections are caused by _.
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worms
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most common infectious disease of human beings
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dental caries
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Dissolution of the tooth surface due to the metabolic action of bacteria Results in minor to complete disruption of enamel
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dental caries
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What are the main causative agents of dental caries (cavities)?
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Streptococcus mutans Streptococcus sobrinus
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Dental caries incidence varies according to _ consumption, _ hygiene, and _ factors.
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carbohydrate oral genetic
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What is the most common mode of transmission for dental caries?
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direct contact
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What are the virulence factors or dental caries?
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adhesion acid production
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What are 2 prevention techniques against dental caries?
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oral hygiene fluoride supplementation
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What is the treatment for dental caries?
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removal of diseased tooth material
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Epidemiological features of dental caries: _-_% prevalence in school-aged children.
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60-90
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Periodontitis is a _ to dental caries.
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sequelae
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first phase in periodontal disease
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gingivitis
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Swelling, loss of normal contour, patches of redness, and increased bleeding Spaces or pockets develop between the tooth and gingiva Disease extends into the periodontal membrane and cementum Deeper involvement increases the size of pockets, causes bone resorption, and tooth loss
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gingivitis (periodontitis)
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"trench mouth" (WWI poor oral hygiene) severe pain bleeding pseudomembrane formation necrosis
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Necrotizing Ulcerative Gingivitis and Periodontitis
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Gingivitis and periodontitis synergistic infections include: (3)
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Treponema vincentii Prevotella intermedia Fusobacterium species
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Periodontitis causative agents include: (3)
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tannerella forsythia aggregatibacter actinomycetemcomitans porphyromonas gingivalis
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What are the virulence factors of periodontal disease? (2)
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induction of inflammation enzymatic destruction of tissues
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Prevention of periodontal disease:
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oral hygiene
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Treatment of periodontal disease:
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removal of plaque/calculus gum restoration possibly anti-inflammatory treatments
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Epidemiological features of periodontal disease in the U.S.: smokers= _% nonsmokers=_% internationally: _-_% of all adults
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11 2 10-15
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Causative agents of Necrotizing Ulcerative Gingivitis and Periodontitis: (3)
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treponema vincentii prevotella intermedia fusobacterium species
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Virulence factors of Necrotizing Ulcerative Gingivitis and Periodontitis: (2)
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inflammation invasiveness
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Prevention against Necrotizing Ulcerative Gingivitis and Periodontitis:
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oral hygiene
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Treatment of Necrotizing Ulcerative Gingivitis and Periodontitis: (2)
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debridement of damaged tissue possibly antibiotics
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Nasal discharge, muscle pain, malaise Inflammation of the salivary glands producing gopherlike swelling of cheeks Can invade other organs: testes, ovaries, pancreas, meninges, heart, and kidney
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mumps
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20 - 30% of young adult males, Mumps localizes in the epididymis and testes, but does not cause _.
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sterility
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Mumps can be prevented by the _ vaccine.
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MMR
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Causative agent of mumps
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mumps virus (genus paramyxovirus)
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Most common mode of transmission for mumps:
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droplet contact
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Virulence factors of mumps:
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spike-induced syncytium formation
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Culture/Diagnosis for mumps:
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clinical fluorescent Ag tests ELISA for Ab
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Prevention against mumps:
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MMR live attenuated vaccine
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Treatment for mumps:
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supportive
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Epidemiological features of mumps US: fluctuates between a few _ and a few _ a year internationally: epidemic peaks every _-_ years
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hundred/thousand 2-5
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sharp or burning pain emanating from the abdomen
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Gastritis
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lesions on the stomach or uppermost portion of the small intestine
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gastric/peptic ulcers
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Causative agent of Gastritis and Gastric Ulcers:
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helicobacter pylori
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Helicobacter pylori infects _ of world's population.
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1/2
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Virulence factors of Gastritis and Gastric Ulcers:
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adehesions urease
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Culture/Diagnosis of Gastritis and Gastric Ulcers:
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endoscopy urea breath test stool antigen test
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Prevention for Gastritis and Gastric Ulcers:
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none
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Treatment for Gastritis and Gastric Ulcers:
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amoxicillin followed by clarithromycin and tinidazole
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Epidemiological features of Gastritis and Gastric ulcers: US: infection rates at _% of adults internationally: infection rates at _%
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35 50
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Defined as 3 or more loose stools in a 24 hour period
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Acute Diarrhea (With or Without Vomiting)
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Statistics of Diarrhea: US: average of _ - _ cases per person per year. _ transmitted by contaminated food. In tropical countries, children experience _ episodes per year. More than _ children die from diarrhea per year, mostly in developing countries.
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1.2-1.9 1/3 10 3 M
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Enteric fever or gastroenteritis: can range from mild diarrhea to fever and septicemia Typhoid fever: progressive, invasive infection that eventually leads to septicemia characterized by fever, diarrhea, and abdominal pain Ability to cause disease is dependent on its ability to adhere to gut mucosa Has a high ID50
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Signs and symptoms of salmonella
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_ cases and _ deaths a year due to Salmonella.
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1.2 M 500
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Gram-negative straight rods, nonmotile, and non-endospore-forming Frequent, watery stools, and intense abdominal pain, Dysentery
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shigella
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most severe form of shigella
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shigella dysenteriae
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Shigella _ and Shigella _ cause 20,000-25,000 cases per year, half in children.
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sonnei flexerni
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diarrhea containing blood
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dysentery
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Shigella invades the _ cells of the _ _, but does not perforate the intestine or invade the blood.
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villus large intestine
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Shigella invades villus cells of the large intestine as well as release _, causing fever.
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endotoxin
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affects the entire GI tract, damages the mucosa and villi, and gives rise to bleeding and secretion of mucus (shigella)
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enterotoxin
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responsible for more serious damage to the intestine as well as systemic effects (shigella)
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shiga toxin
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Symptoms of Shigella range from mild gastroenteritis to fever with bloody diarrhea with the Shiga-Toxin-Producing E. coli, _.
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E. coli O157:H7
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severe hemolytic anemia that can cause kidney damage and failure
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Hemolytic uremic syndrome
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Toxins identical to shiga toxins produced by Shigella
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E. coli O157:H7
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Transmission through the ingestion of undercooked beef and other contaminated foods and beverages
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E. coli O157:H7
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traveler's diarrhea, watery diarrhea, low-grade fever, nausea, and vomiting
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Enterotoxigenic E. coli
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bacillary dysentery, blood and mucus in the stool, more common in developing countries
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Enteroinvasive E. coli
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profuse, watery diarrhea, with fever and vomiting, produce effacement of gut surfaces
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Enteropathogenic E. coli
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causes diarrhea in young patients and AIDS patients
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Enteroaggregative E. coli
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typically associated with the development of urinary tract infections; may play a role in inflammatory bowel disease
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Diffusely adherent E. coli
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most common cause of bacterial diarrhea in the United States
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Campylobacter
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Frequent watery stools, fever, vomiting, headaches, and severe abdominal pain Symptoms may last longer than 2 weeks
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Campylobacter
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Slender, curved or spiral gram-negative bacteria with polar flagella
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Campylobacter
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Microaerophilic inhabitants of the intestinal tracts of animals and humans
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Campylobacter
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Gram-positive endospore-forming rod found as normal biota of the intestine. Pseudomembranous colitis, antibiotic-associated colitis Precipitated by therapy with broad-spectrum antibiotics Enterotoxins A and B cause necrosis in the wall of the intestine
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Clostridium difficile
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Treatment of Clostridium difficile: (3)
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Withdrawal of antibiotics, replacement of fluids Metronidazole Fecal transplant
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Comma-shaped rod with single polar flagellum
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Vibrio cholerae
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Vomiting, copious watery feces, "rice-water stool" Fluid losses of 1 liter per hour in severe cases Loss of blood volume, acidosis, potassium depletion, muscle cramps, severe thirst, flaccid skin, and sunken eyes, leading to convulsions and coma Hypotension, tachycardia, cyanosis, shock
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Vibrio cholerae
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Vibrio cholerae has a _ - _% mortality rate.
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55-70
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disrupts the normal physiology of intestinal cells, causing them to shed large amounts of electrolytes into the intestine
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Cholera toxin
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Pathogenesis and virulence factor of Vibrio cholerae:
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Cholera toxin
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Transmission and epidemiology of Vibrio cholerae:
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Warm, monsoon, alkaline, and saline conditions favor growth of vibrio
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Treatment of Vibrio cholerae:
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Oral rehydration therapy
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Intestinal apicomplexan protozoan Hardy intestinal oocyst as well as a tissue phase Penetrates intestinal cell walls and lives intracellularly Oocysts are highly infectious and resistant to chlorine treatment
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Cryptosporidium
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Outbreaks of Cryptosporidium are associated with _.
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swimming pools
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Symptoms of crytosporidiosis generally begin _-_ days (average _ days) after becoming infected with the parasite.
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2-10 7
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Symptoms of crytosporidiosis include: (7)
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watery diarrhea stomach cramps or pain dehydration nausea vomiting fever weight loss
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Double-stranded RNA genome with both an inner and outer capsid
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Rotavirus
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primary cause of morbidity and mortality resulting from diarrhea
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rotavirus
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_-_ million cases per year of rotavirus. _ hospitalizations.
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2-3 700,000
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Rotavirus is transmitted by:
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fecal-oral route
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Treatment for rotavirus includes:
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oral rehydration therapy fluid replacement
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_ and _ are vaccines that are available to prevent against rotavirus.
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Rotarix RotaTeq
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a type of fluid replacement used to prevent and treat dehydration, especially that due to diarrhea Therapy should routinely include the use of zinc supplements. Use of oral rehydration therapy decreases the risk of death from diarrhea by about 93%.
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Oral rehydration therapy (ORT)
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involves drinking water with modest amounts of sugar and salts; can be given by a nasogastric tube
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Oral rehydration therapy (ORT)
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Oral rehydration therapy should routinely include the use of _ supplements.
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zinc
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Use of oral rehydration therapy decreases the risk of death from diarrhea by about _%.
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93
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Most common viral cause of food-borne disease in the United States
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norovirus
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Profuse, watery diarrhea for 3 - 5 days, vomiting in the early stages Low infectious dose: 1 - 20 viruses
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norovirus
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Norovirus has many outbreaks associated with _.
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cruise ships
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Transmission for Norovirus:
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Fecal-oral transmission or via contamination of food and water
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Nausea and vomiting accompanied by diarrhea, often companions that shared a meal suffer the same fate Symptoms in the gut caused by a preformed toxin Occasionally comes from nonmicrobial sources such as fish, shellfish, or mushrooms Intoxication rather than infection
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food poisoning
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Associated with custards, sauces, cream pastries, processed meats, chicken salad, or ham
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Staphylococcus aureus Exotoxin
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Staphylococcus aureus thrives due to high _ tolerance.
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salt
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_ is heat stable and induces symptoms of cramping, nausea, vomiting, and diarrhea in food poisoning. Onset within 1 - 6 hours, recovery within 24 hours Self-limiting, antibiotics not warranted
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Enterotoxin
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The onset of Staphylococcus aureus Exotoxin is within _-_ hours, and recovery is within _ hours.
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1-6 24
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Staphylococcus aureus Exotoxin are _-_, antibiotics not warranted.
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self limiting
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Sporulating gram-positive bacterium that lives in the soil
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Bacillus cereus Exotoxin
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Emetic form most frequently tied to fried rice that has been cooked and kept warm for long periods of time
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Bacillus cereus Exotoxin
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Diarrheal form associated with cooked meats or vegetables held at a warm temperature for long periods of time (Profuse, watery diarrhea that lasts about 24 hours)
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Bacillus cereus Exotoxin
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Also the causative agent of gas gangrene
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Clostridium perfringens Exotoxin
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Contaminates meat, fish, and vegetables and beans that have not been cooked properly
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Clostridium perfringens Exotoxin
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Endospores germinate in foods, C. perfringens cells enter the _ and release exotoxin.
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small intestine
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Abdominal pain, diarrhea and nausea lasting 8 - 16 hours Also causes enterocolitis similar to that caused by C. difficile
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Clostridium perfringens Exotoxin
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Diarrhea lasting longer than 14 days Can have an infectious or noninfectious cause Irritable bowel syndrome, ulcerative colitis AIDS patients universally suffer from *THIS*
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Chronic Diarrhea
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Associated with chronic disease, particularly in children and those who are malnourished. Adheres to human cells in aggregates rather than single cells Stimulates large amounts of mucus in the gut Transmission through food and water
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Enteroaggregative E. coli
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Cyclospora cayetanensis is a _.
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protozoan
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Emerging pathogen; numerous outbreaks in the US and Canada in the past years
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Cyclospora cayetanensis:
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Fecal-oral transmission and through the consumption of fresh produce and water contaminated with feces Oocysts are not observable in the feces, but can be visualized when exposed to UV light
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Cyclospora cayetanensis
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Symptoms: watery diarrhea, stomach cramps, bloating, fever, muscle aches
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Cyclospora cayetanensis
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People become infected with Cyclospora by ingesting _, which are the infected form of the parasite. This most commonly occurs when food or water contaminated with feces is consumed. An infected person sheds unsporulated (immature, non-infective) Cyclospora oocysts in the feces.
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spoulated oocysts
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The oocysts are thought to require days to weeks in favorable environmental conditions to _ (become infective). Therefore, direct person-to-person transmission is unlikely, as is transmission via ingestion of newly contaminated food or water.
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sporulated
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Pathogenic flagellated protozoan
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Giardia
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Signs and symptoms: diarrhea of long duration, abdominal pain, flatulence, greasy, malodorous stools
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Giardia
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Complex epidemiological pattern Isolated from beavers, cattle, coyotes, cats, and human carriers
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Giardia
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Giardia cysts survive for up to _ months in the environment Epidemics traced to water from mountain streams as well as chlorinated municipal water.
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2
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_ infection is an intestinal infection marked by abdominal cramps, bloating, nausea and bouts of watery diarrhea. *This* is caused by a microscopic parasite that is found worldwide, especially in areas with poor sanitation and unsafe water.
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Giardia
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Exists in intestinal and extraintestinal form
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Entamoeba
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Targets the cecum, appendix, colon, and rectum Actively penetrates deeper layers of mucosa Dysentery, Abdominal pain, diarrhea, fever, and weight loss Can lead to hemorrhage, perforation, appendicitis, and amoebomas Humans are primary hosts; infection through food and water contaminated with cysts
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Entamoeba
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_ is a disease caused by the parasite Entamoeba histolytica. It can affect anyone, althought it is more common in people who live in tropical areas with poor sanitary conditions.
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Amebiasis
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Diagnosis of _ can be difficult because other parasites can look very similar to E. histolytica when seen under a microscope
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Amebiasis
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Inflammatory disease of the liver
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hepatitis
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Necrosis of hepatocytes
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hepatitis
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Response by mononuclear white blood cells that swells and disrupts the liver architecture
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hepatitis
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Interferes with excretion of bile pigments and causes bilirubin to accumulate in blood and tissues, causing jaundice
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hepatitis
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Non enveloped, single-stranded RNA virus. Signs and symptoms: Subclinical or vague, flulike symptoms Jaundice in only 10% of cases dependent upon patient Transmission and epidemiology: Fecal-oral route, associated with deficient personal hygiene and lack of public health measures Immunizations are available
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hepatitis a
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Enveloped DNA virus. Signs and symptoms: Fever, chills, malaise, anorexia, abdominal discomfort, diarrhea nausea Rashes and arthritis may occur Causes hepatocellular carcinoma Transmitted by minute amounts of blood. An effective vaccine is available. Especially important for healthcare workers
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hepatitis b
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Silent epidemic: 4.1 million Americans infected. Signs and symptoms: Similar to hepatitis B virus 75 - 85% remain infected indefinitely Transmission and epidemiology: Blood transfusions, needle sharing Treatment: No vaccine available Pegylated interferon, ribavirin, protease and polymerase inhibiting drugs "Harvoni"- new and effective chemotherapeutic
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hepatitis c
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Amazing _ among helminths that parasitize humans.
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diversity
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_ (high eosinophil count) is a hallmark of helminthic infection.
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Eosinophilia
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Cause a large burden of disease in the poorest countries in the world Receive the least recognition and research funding
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Neglected tropical diseases
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Specialized parts for attachment, enzymes to penetrate tissues, cuticle for protection from host defenses; definitive host
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pathogenesis and virulence factors of gastrointestinal tract diseases caused by helminths
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host in which the adult worm reproduces sexually
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definitive host
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diagnosis of gastrointestinal tract diseases caused by helminths
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Eosinophilia Discovery of eggs, larvae, or adult worms in stool and tissues
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What are the preventions and treatments of gastrointestinal tract diseases caused by helminths? (7)
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No vaccines available Regular treatment with antihelminthic drugs Proper sewage disposal Avoiding using human feces as fertilizer Disinfection of the water supply Thoroughly washing and cooking vegetables and meats Freezing food
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Whipworm
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Trichuris trichuria
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Life Cycle A Highest incidence in the tropics and subtropics that have poor sanitation
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Trichuris trichuria (whipworm)
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Female whipworms lay _-_ eggs daily in the bowel.
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3000 5000
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Symptoms of whipworm (Trichuris trichuria): (4)
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localized hemorrhage of the bowel dysentery loss of muscle tone rectal prolapse
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Pinworm
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Enterobius vermicularis
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Most common worm disease of children in temperate zones Life Cycle A
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Enterobius vermicularis (Pinworm)
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Hallmark symptom of enterobius vermicularis (pinworm)
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pronounced anal itching
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Pinworm Infection is not fatal and most cases are _.
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asymptomatic
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Tapeworm (pigs)
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Taenia solium
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Adult tapeworms are up to _ meters long.
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5
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Tapeworms (Taenia solium) are distributed worldwide, but concentrated in areas where humans live in close proximity with _ or eat undercooked _.
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pigs pork
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Tapeworms (Taenia solium) go through Life Cycle _.
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C
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Symptoms of tapeworm (tania solium)
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Proglottids in stool Vague abdominal pain and nausea
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tapeworms (fish)
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Diphyllobothrium latum
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Has an intermediate fish host Can be transmitted in sushi and sashimi Also transmitted through undercooked or smoked trout, perch, or pike Common in the Great Lakes, Alaska, and Canada
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Tapeworm (Diphyllobothrium latum)
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Symptoms of tapeworm (diphyllobtherium latum): (2)
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abdominal discomfort or nausea anemia
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Giant intestinal roundworm
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Ascaris lumbricoides
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Larval and adult stages in humans, embryonic eggs expelled in feces Penetrate intestinal wall and enter lymphatic and circulatory systems Swept into the heart and arrive at capillaries in the lungs Migrate up the respiratory tree to the glottis Worms are swallowed and return to the small intestine
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Ascaris lumbricoides
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Hookworm (2)
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Necator americanus Ancylostoma duodenale
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endemic to the New World
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Necator americanus
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endemic to the Old World
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Ancylostoma duodenale
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Hatch outside the body and infect by penetrating the skin
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hookworms
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Hookworms take Life Cycle _.
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B
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localized dermatitis (hookworm)
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ground itch
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result of transit of the worms to the lung (hookworm)
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Pneumonia and eosinophilia
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Heavy worm burden in the intestine can cause _, _, _, _, and _.
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nausea vomiting cramps bloody diarrhea anemia
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Both known as Chinese liver flukes
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Opsithorcis sinensis and Clonorchis sinensis
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Opsithorcis sinensis and Clonorchis sinensis take on Life Cycle _.
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D
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Larvae of Opsithorcis sinensis and Clonorchis sinensis hatch and crawl into the bile duct, shed eggs into the _ tract.
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intestinal
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Symptoms of infection from Opsithorcis sinensis and Clonorchis sinensis: (4)
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Slow to develop Thickening of the lining of the bile duct granuloma formation in areas of the liver Bile duct may be blocked
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Liver fluke common in sheep, cattle, goats, and other animals
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Fasciola hepatica
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Outbreaks associated with eating wild watercress Complex life cycle, mammal is the definitive host
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Fasciola hepatica
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Symptoms of Fasciola hepatica: (4)
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vomiting diarrhea hepatomegaly bile obstruction of infected with a large number of flukes
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Transmitted by eating pork and sometimes other wildlife. Symptoms range from unnoticeable to life threatening 2 phases
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Muscle and Neurological Symptoms: Trichinosis
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What are the 2 phases of Muscle and Neurological Symptoms: Trichinosis?
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First phase: diarrhea, nausea, abdominal pains, fever, sweating Second phase: puffiness around the eyes, intense muscle and joint pain, shortness of breath, eosinophilia Prevention through adequate storage and cooking of pork and wild meats
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