GI Worms Protozoa Diarrheals & Hepatitis Flashcards
Entamoeba Histolytica: Transmission
Fecal oral route by contamination of food or water with infective cysts
Entamoeba Histolytica: Clinical disease
Commonly asymptomatic (carrier state). Acute disease it can present as severe dysentery with numerous small stools containing blood, mucous and shreds of necrotic mucosa. Disseminated infections occur when not detected early. Primarily spreads to the liver (lung and brain possible) and is more common in immunocompromised host
Entamoeba Histolytica: Morphology (shape, # of nuclei, #of flagella, cytoplasmic appearance)
Trophozoites have ameboid shape, ground glass cytoplasm, a solitary nucleus, no flagella and often RBC inclusion bodies. Cysts are spherical with 1-4 nuclei and might contain chromatoid bodies (sausage shaped)
RBC inclusion bodies are often seen in what organsim
Entamoeba Histolytica
Acanthamoeba: Transmission
Direct contact (as with the contact lense epidemic) or inhalation
Acanthamoeba: Clinical disease
Immunocompromised: More common, causes pneumonitis (lung inflammation), dermal ulceration, and slowly progressive but fatal encephalitis. Healthy individuals: Can cause ulcerative keratitis (eats the cornea) resulting from contaminated contact lenses.
This organism was responsible for the keratitis outbreak in schools after kids started sharing their color contacts
Acanthamoeba
Naegleria fowleri: Transmission
Swimming in warm bodies of fresh water, such as ponds, lakes, rivers, and hot springs. Enters brain via olfactory route (cribriform plate)
Naegleria fowleri: Clinical disease
Affects healthy and immunocompromised individuals by causing primary amebic meningoencephalitis, a rapidly progressing and almost invariably fatal disease (the case fatality rate is estimated at 98%)
Infection with this organsim almost always results in death (98% mortality rate)
Naegleria fowleri
Giardia Lamblia: Transmission
Ingestion of infected water or by anal/oral sexual contact
Giardia Lamblia: Clinical disease
Trophozoites coat villi of small intestine, interfering with the absorption of fat, and fat soluble nutrients such as vitamin B12, carotene, and folate. Symptoms: epigastric pain and non-bloody diarrhea (steatorrhea)
Giardia Lamblia: Morphology (shape, # of nuclei, #of flagella, cytoplasmic appearance)
Trophozoite is pear shaped with sucking disk, 2 nuclei that resmble eyes and 4 pairs of flagella. Cyst is football shaped with 2-4 nuclei and axonemes
Infection with which organism is the most common (in the USA) of the intestinal protozoan infections
Giardia Lamblia
Trichomonas vaginalis: Transmission
Sexual contact, contaminated towels, wash cloths, and clothing (can survive on fomites up to 24 hours)
Trichomonas vaginalis: Clinical disease
Trophozoites feed on the mucosal surface of the vagina resulting in inflammation, vaginal irritation, burning, and purulent discharge. Infection in males may be asymptomatic and harder to detect. Prostatic inflammation is most common symptom
Trichomonas vaginalis: Morphology (shape, # of nuclei, #of flagella, cytoplasmic appearance)
Trophozoite is oval or pear shaped with 1 nucleus. Has 4 flagella, and a characteristic undulating membrane. Its axoneme appears to protrude from the posterior but is actually covered by membrane
Cryptosporidium parvum: Transmission
Ingestion of infected water or by anal/oral sexual contact
Cryptosporidium parvum: Clinical disease
Immunocompromised: An opportunistic infection seen in AIDS patients that causes chronic life threatening infection with profuse watery diarrhea. Immunocompetent: Profuse watery diarrhea that is self-limiting.
This organism is acid fast and resistant to chlorination
Cryptosporidium parvum
This organism is similar to Cryptosporidium parvum except its larger. It is also acid fast.
Cyclospora cayetanensis
Cyclospora cayetanensis: Transmission
Contaminated fruit
Which three infection-causing protozoans of the GI tract are acid fast
Cryptosporidium parvum, Cyclospora cayetanensis, Isospora belli
Isospora belli: Clinical disease
Similar to Cryptosporidium. Causes acute, non-bloody diarrhea with crampy abdominal pain, which can last for weeks and result in malabsorption and weight loss. In immunodepressed patients, and in infants and children, the diarrhea can be severe.
This organsim is the only known ciliate to cause human disease and has a major reservoir in swine
Balantidium coli
This organism is similar to Entamoeba Histolytica except for what difference
Balantidium coli except it very rarely invades beyond the gut wall (no disseminated infection)
Watery (no blood or mucous) diarrhea sans fever and minimal local inflammatory response occuring 1-8 hrs after ingestion of contaminated food is caused by what two organisms [and is it pre-formed toxin, toxin, or organism mediated]
Bacillus Cereus or Staph Aureus [Pre-formed toxin]
Watery (no blood or mucous) diarrhea sans fever and minimal local inflammatory response occuring 18-36 hrs after ingestion of contaminated food is caused by what four organisms [and is it pre-formed toxin, toxin, or organism mediated]
Enterotoxigenic E. Coli, Vibrio cholera, Clostridium Perfingens, or Bacillus Cereus [Toxin produced in GI tract]
Dysentery and fever occuring 2-4 days after ingestion of contaminated food is caused by what four organisms [and is it pre-formed toxin, toxin, or organism mediated]
Campylobacter jejuni, Salmonella, Shigella, or Enteroinvasive E. Coli
Various GI symptoms occuring 7-10 days after ingestion of contaminated food is caused by what three organisms [and is it pre-formed toxin, toxin, or organism mediated]
Giardia, Cryptosporidium, or Entamoeba
How does cholera toxin work
It migrates across membrane of small bowel mucosa cell to stimulate adenylate cyclase which stimulates cyclic AMP which stimulates secretion of electrolytes into bowel lumen
Which 5 organisms cause dysentery (partially invade gut)
Shigella, Campylobacter Jejuni, Clostridium difficile, Invasive E. Coli, and Entamoeba Histolytica
Which 2 organisms fully invade the gut
Salmonella typhi and Yersinia
This diarrhea-causing organism is an aerobic, curved gram-negative rod. Infection is associated with salt water exposure
Vibrio cholera
This diarrhea-causing organism is the most common bacterial cause of diarrhea
Campylobacter jejuni
This diarrhea-causing organism is a microaerobic, curved gram-negative rod. Infection is associated with chickens and unpasteurized milk
Campylobacter jejuni
This diarrhea-causing organism is a non-spore-forming aerobic gram negative rod. Infection is associated with chickens, turkeys, cows, pigs, pets, and unpasteurized milk
Salmonella
This kind of E. Coli causes watery diarrhea in travellers
Enterotoxigenic (or enteroaggregative)
This kind of E. Coli causes watery diarrhea in children
Enteropathogenic (or enteroaggregative)
This kind of E. Coli causes febrile severe diarrhea particularly in developing cultures
Enteroinvasive
This kind of E. Coli causes afebrile, gross blood, associated with hemolytic/uremic syndrome
Enterohemorrhagic
What Diarrhea-causing virus is a Reovirus (segmented double stranded RNA, icosahedral virion, double capsid, and no envelope)
Rotavirus
What Diarrhea-causing virus is a Calicivirus (positive sense single stranded RNA, icosahedral virion with no envelope)
Norovirus
What is the incubation period of Rotavirus
24-72 hours
This virus is icosahedral, lacks an envelope, and has linear double-stranded DNA genome
Adenovirus
Which Serotypes of the Adenovirus cause acute viral gastroenteritis in infancts that is often associated with concurrent respiratory tract infection
40, 41, and 42
What is the incubation period of Norovirus
6-24 hours
Who does Rotavirus usually infect
Infants <2 yrs
Who does Norovirus usually infect
School age children and adults
Diphyllobothrium latum: Transmission and Intermediate/difinitive host
Transmission: Ingestion of undercooked cooked freshwater fish containing the infective pleurocercoid. Intermediate host: Copepod and freshwater fish Difinitive host: Humans
Which organism causes the following clinical disease: Pretty minor, digestive upset, abdominal discomfort, weight loss, and weakness. Pernicious anemia can develop in cases where worms attach in the upper small intestine (out competes for B12)
Diphyllobothrium latum
This is the largest tapeworm in humans
Diphyllobothrium latum
Taenia Solium: Transmission and Intermediate/difinitive host
Transmission: Ingestion of undercooked pork infected with cysticercus causes GI infection. Fecal/oral ingestion of eggs can cause intermediate host infection of brain (cysticercosis). Intermediate host: Pigs. Difinitive host: Humans
Cysticersosis is caused by infection with what organsim
Taenia Solium
Taenia Solium: Morphology (# of suckers, # of hooks, # of uterine branches)
Scolex with 4 suckers, double row of hooks, gravid proglottids <12 uterine branches
Taenia Saginata: Transmission and Intermediate/difinitive host
Transmission: Ingestion of undercooked beef infected with cysticercus causes GI infection. Intermediate host: Cows. Difinitive host: Humans
Taenia Solium & Taenia Saginata: Clinical disease
Few symptoms including abdominal discomfort, mild irritation of the intestinal mucosa from adult worm, and discomfort of the proglottids crawling out of the anus
Taenia Saginata: Morphology (# of suckers, # of hooks, # of uterine branches)
Scolex with 4 suckers, no hooks, gravid proglottids >12 uterine branches
The clinical disease of this organism includes: Cutaneous-little reaction. Repeat infection can cause allergic response. Pulmonary effects include coughing, shortness of breath, wheezing. Abdominal effects include pain, diarrhea, indigestion, and nausea possibly mimicking an ulcer. Hyperinfection in immunocompromised patients can lead to disseminated infection that can result in death due to sepsis
Strongyloides stercoralis
Strongyloides stercoralis: Intermediate (reservoir) host and difinitive host
Intermediate (reservoir): Cats and dogs. Difinitive host: Humans
This organism can continually autoinfect the human host causing a chronic infection in immunocompromised patients that can last decades
Strongyloides stercoralis
This organism is microscopic in the adult form and would be found buried in the submucosa of the intestine but is barely ever seen
Strongyloides stercoralis
Necator americanus & Ancylostoma duodenale: Transmission and life cylce
Transmission: Skin contact with soil. Life cycle: Rhabditiform larvae develop into filariform larvae in the soil. Filariform enters skin, is carried to heart and lungs by blood, enters the alveoli, migrates to trachea and is swallowed, matures into adult in the intestine
Necator americanus & Ancylostoma duodenale: Clinical disease
Cutaneous phase: Ground itch. Pulmonary phase: Pneumonitis. Intestinal phase: Iron deficiency anemia
Which organisms are transmitted by penetrating the skin
Necator americanus & Ancylostoma duodenale
Enterobium vermicularis: Clinical disease
Perianal itching, behavioral changes (insomnia and irritability)
This is the world’s most common parasite. It most commonly affects children
Enterobium vermicularis
This organism can cause bowel obstruction if large number of worms are present (worm ball)
Ascaris lumbricoides
Ascaris lumbricoides: Transmission and life cylce
Transmission: Eggs are ingested. Life cylce: Larvae develop within the egg. When egg is ingested, the larvae penetrate the gut an travel to liver->lung->trache->esophagus. They are swallowed and become adults in the intestine
Ascaris lumbricoides: Clinical disease
Pneumonitis when larvae migrate through tissue, bowel obstruction (worm ball), abnormal migration is possible and may cause inflammation in affected tissues.
Best markers for current acute HBV infection
IgM anti-HBc & HBsAg
Best markers for past HBV infection
IgG anti-HBs & IgG anti-HBc In the absence of HBsAg
What markers will be present in an HBV vaccinated individual
IgG anti-HBs but no anti-HBc
Best marker for chronic HBV infection
HBsAg longer than 6 months but no anti-HBs
Best markers for HBV infectivity
HBV DNA or HBeAg
Diagnose: HBsAg: + Anti-HBs: - HBeAg: + Anti-HBe: - Anti-HBc: IgM
Acute HBV
Diagnose: HBsAg: - Anti-HBs: - HBeAg: - Anti-HBe: + Anti-HBc: IgM
HBV Window Period
Diagnose: HBsAg: + Anti-HBs: - HBeAg: + Anti-HBe: - Anti-HBc: IgG
High infectivity Chronic HBV
Diagnose: HBsAg: + Anti-HBs: - HBeAg: - Anti-HBe: + Anti-HBc: IgG
Low infectivity Chronic HBV
Diagnose: HBsAg: - Anti-HBs: + HBeAg: - Anti-HBe: + Anti-HBc: IgG
Recovery from HBV infection
Diagnose: HBsAg: - Anti-HBs: + HBeAg: - Anti-HBe: - Anti-HBc: -
Immunized against HBV
This Hepatitis virus is a Picornavirus
HAV
This Hepatitis virus is a Hepadnavirus
HBV
This Hepatitis virus is a Flavivirus
HCV
This Hepatitis virus is a Delta Virus
HDV
This Hepatitis virus is a Hepevirus
HEV
Which Hepatitis virus requires infection with which other hepatitis virus
HDV requires HBV infection
Which Hepatitis viruses carry a risk of Hepatocellular Carcinoma
HBV, HCV, & HDV
Which Hepatitis viruses are transmitted by blood or sexual contact
HBV, HCV, & HDV
Which Hepatitis viruses are transmitted by fecal oral route
HAV & HEV
Which Hepatitis viruses are naked viruses
HAV & HEV
When does a Hepatitis superinfection occur
When an HBV infected individual is infected with HDV
What is the standard treatment option for HBV & HCV
Alpha-interferon + Ribovirin
What percent of symptomatic HBV infected individuals develop acute vs chronic disease
Acute: 90% Chronic: 10%
What percent of symptomatic HCV infected individuals develop acute vs chronic disease
Acute: 20% Chronic: 80%
Which Hepatitis Virus causes high mortality in pregnant women
HEV
How do liver enzymes ALT and AST compare in viral hepatitis
ALT > AST
How do liver enzymes ALT and AST compare in alcoholic hepatitis
AST > ALT
IgM Anti-HAV Indicates what
Active HAV infection
IgG Anti-HAV indicates what
Prior HAV infection and/or HAV vaccination
