Parasitic Diseases of GI tract

Question 1

giardia lamblia description

Answer 1

zoonosis, cross infectivity among beavers, cattle, dogs, rodents, sheep. Very common cause of travelers’ diarrhea

Question 2

giardia transmission

Answer 2

ingestion of cysts in contaminated food/water. cysts can survive several months in cold water. following ingestion, excystation occurs in the proximal small bowel with release of trophozoites

Question 3

clinical presentation of giardia

Answer 3

1-2 week incubation. acute onset of diarrhea, abdominal cramps, bloating, flatulence. malaise, nausea, anorexia, sulfuric belching. weight loss.

Question 4

giardia treatment

Answer 4

metronidazole most commonly used.

Question 5

cryptosporidiosis description

Answer 5

coccidian with a lifecycle similar to plasmodium without a secondary host lifecycle. small parasite in the stool, need a specific stain to see it. survives normal chlorination in the water supply

Question 6

sources of cryptosporidium

Answer 6

common cause of calf diarrhea. kids get it from petting zoos. can be seen in drinking waters

Question 7

how many oocysts are needed to cause infection with cryptosporidium?

Answer 7

as few as 4! low infectious dose

Question 8

what was the cause of the seneca lake state park spray park outbreak?

Answer 8

cryptosporidium. initial contamination likely caused persistent contamination, resulting in ongoing transmission. extreme tolerance to chlorine

Question 9

cryptosporidiosis clinical presentation

Answer 9

7-14 day incubation. immunocompetent: self limiting watery diarrhea for 10-14 days. immunocompromsied: severe, chronic, incurable.

Question 10

cryptosporidiosis treatment

Answer 10

fluid and electrolyte support. nitazoxanide in immunocompetent host shortens duration of symptoms

Question 11

pathogenic entamoeba species

Answer 11

e. histolytica

Question 12

what does it mean if you detect nonpathogenic entamoeba in person’s poop?

Answer 12

this means the patient has ingested water contaminated with human waste!

Question 13

e. histolytica description

Answer 13

fecal-oral. poor hygiene during food prep or by use of night soil: fertilizing crops with human poop. oral sex practices. 2nd most common cause of diarrhea in returning travelers

Question 14

how does e. histolytica cause disease

Answer 14

can disrupt the mucus layer overlying the colonic mucosa, causing bleed and colitis. trophozites penetrate intestinal wall and spread through body via portal circulation. form liver abscesses

Question 15

hepatic disease due to e. histolytica

Answer 15

infection may result in hematogenous spread of the organisms from the submucosa to the liver via the portal system, causing abscesses of the liver. can rupture into the pleural space. presents with fever, right upper quadrant/shoulder pain, rarely diarrhea

Question 16

human taeniasis

Answer 16

parasitic infection caused by T. saginata or T. solium. humans are only hosts. cows and pigs are infected by eating contaminated food. eggs hatch into animal’s intestine and go to the muscle. humans eat the meat and get the worms

Question 17

taenia saginata description

Answer 17

beef tapeworm. found in meat of cattle. consumption of measly uncooked or undercooked beef transmits it. large in the human, 10m, and contain 1000 proglottids, each capable of making 1000s of eggs

Question 18

taenia solium description

Answer 18

pork tapeworm. humans can be intermediate or definitive hosts. ingest eggs develop tissue infection with cysts, aka cysticercosis. occurs in mexico, central and south america, africa, asia, india, philippines, southern europe.

Question 19

taenia solium cysticercosis development

Answer 19

humans get intestinal infection with adult worms after eating contaminated pork. pigs or humans become infected by ingesting eggs. eggs hatch in intestine and release oncospheres, which penetrate the wall. travel to the bloodstream to striated muscle and brain/liver/other organs

Question 20

cysticercosis

Answer 20

tissue infection with larval cysts of T. solium in which patient serves as an intermediate host. usually harbor cysts in many parts of the body. neurocysticercosis is term for CNS involvement.

Question 21

neurocysticercosis

Answer 21

CNS involvement. any part of CNS, but symptoms usually related to intercerebral lesions. seizures, mass effects

Question 22

diphyllobothrium description

Answer 22

fish tapeworm. human infection acquired by eating uncooked freshwater fish containing the parasite’s cysts. 3-6 weeks for tapeworm to mature. 30 year lifespan. usually asymptomatic, sometimes causes B12 deficiency because the worm absorbs it

Question 23

ascariasis

Answer 23

most common helminthic infection. live and mate in lumen of the small intestine, mainly the jejunum. 200,000 eggs made by female worm. eggs become infective only on soil in warm, humid environments

Question 24

ascaris lifecycle

Answer 24

eggs pass in feces and embryonate in soil in 10-14 day. eggs hatch in intestine and the liberated larva penetrate the mucosa and pass to the liver via portal vessels, then go to lungs. after a few weeks, larva penetrate the alveolar air sac, passes up the pulmonary tree, coughed up, and swallowed. mature in the small intestine and make eggs in 60-75 days

Question 25

what can heavy ascaris infections cause

Answer 25

intestinal obstruction, intussusception, volvulus, blockage of bile ducts, cholangitis and intestinal perforation

Question 26

trichuris trichiura description

Answer 26

whipworm. found in tropical environments. most infected people harbor fewer than 20 worms, young people 5-15 can have 200+. can suffer light or heavy infections. heavy = painful passage of stool, rectal prolapse. kids can become anemic and growth retarded

Question 27

hookworm description

Answer 27

2 nematode species: ancylostoma duodenale, necator americanus. some SE USA places still have this. penetrates up through bottom of foot

Question 28

hookworm transmission

Answer 28

eggs passed in stool, larvae hatch in 1-2 days. penetrate the skin and are carried through the veins to the heart and lungs. ascend to pharynx where they are swallowed. reside and mature in the small intestine

Question 29

hookworm clinical manifestations

Answer 29

light infections are asymptomatic. can have chronic abdominal pain and eosinophilia. iron deficiency anemia and protein energy malnutrition from blood loss are major manifestations.

Question 30

enterobius vermicularis description

Answer 30

pinworm. most common helminthic infection in USA. usually asymptomatic. perianal and perineal pruritis and scratching.

Question 31

pinworm lifecycle

Answer 31

females migrate out of anus at night and lay eggs. eggs hatch and crawl back into rectum sometimes. self infection occurs by transferring eggs to mouth with hands that have scratched the perianal area

Question 32

lab diagnosis of pinworm infection

Answer 32

microscopic ID of the eggs. done in the morning, 2-5 AM. anal swabs can be used

Question 33

strongyloidiasis description

Answer 33

can produce overwhelming infection in immunocompromised people. can replicate and increase in numbers without leaving the host.

Question 34

strongyloides transmission

Answer 34

rhabditiform larva pass in feces. develops into filariform. this penetrates the skin of the foot, goes thru blood to lungs, migrate up and are swallowed. enter intestinal mucosa and mature, female worms make eggs pathogenetically.

Question 35

hyperinfection and disseminated strongyloidiasis

Answer 35

hyperinfection: increased numbers of larvae are found in the intestines and lungs. disseminated has bugs in the CNS, kidneys, liver, etc. pneumonitis with cough, hemoptysis, respiratory failure. diffuse infiltrates on chest Xray. CNS invasion can cause meningitis and brain abscesses. people with HIV get this