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SEM 3 Bacteria, Parasites, Viruses GI > Parasites > Flashcards

Parasites Flashcards

1
Q

Giardia lamblia: pathogenesis

A
  • inhabits duodenum, upper jejunum
  • Forms: trophozoite (cannot survive in stool), cyst

trophozoite adheres to intestinal epithelium by sucking disc–> brush border injury –> stunting and shortening of villi

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2
Q

Giardia lamblia: clinical features

A

diarrhea, fat malabsorption, dull epigastric pain, flatulence, stool with mucus and fat (steatorrhea)

  • can lead to chronic diarrhea, malabsorption, fat, vit A , weight loss
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3
Q

Giardia lamblia: lab diagnosis and treatment

A

detection of cysts and trophozoites in stool

metronidazole / tinidazole

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4
Q

Entamoeba histolytica

A

intestinal and extra-intestinal amebiasis

forms: trophozoite (present in diarrhea) , cyst (only in lumen of colon and formed stool)

oral fecal route

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5
Q

Entamoeba histolytica: Intestinal amebiasis pathogenesis

A
  • amebic colitis (mucosa invaded, trophozoite penetration aided by histolysin into epithelial cell –> damages mucosal epithelium –> necrosis -> ulcers)
  • flask shaped amebic ulcers (multiple ulcers forming large necrotic lesion)
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6
Q

Entamoeba histolytica: intestinal amebiasis clinical features

A
  • diarrhea, abdominal symptoms, dysentery

ameboma: granulomatous pseudotumoural growth –> develops from chronic ulcer

  • necrosis, inflammation, edema of mucosa and submucosa of colon
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7
Q

Entamoeba histolytica: Extraintestinal amebiasis pathogenesis

A

hematogenous spread of trophozoites –> amebic abscesses extraintestinal sites

esp liver –> lysosomal damage and cytokines from inflammatory cells –> liver damage

Liver - thick pus in centre of abscess, trophozoite in abscess, abscess may rupture into lungs and pericardium

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8
Q

Entamoeba histolytica: lab diagnosis

A

trophozoite and cyst in stool
trophozoite in tissue (in pus, in liver biopsy)
serological tests for antigen/antibody

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9
Q

Entamoeba histolytica: treatment

A

luminal amebicides:
Tetracycline

Tissue amebicides: chloroquine

both luminal and tissue: metronidazole

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10
Q

Blastocystis hominis

A
  • large intestine
    Forms:
    1. vacuolated form: large central vacuole, cytoplasm and nuclei pushed to periphery
    2. ameboid form: polymorphous, larger than vacuolated form
    3. granular form
    4. cystic form: thick multilayered cyst wall

oral fecal route

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11
Q

Blastocystis hominis: patho and clinical features

A

-diarrhea, abdominal pain, abdominal distention, nausea, vomiting

  • mostly asymptomatic, mostly immunologically compromised
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12
Q

Blastocystis hominis: lab diagnosis and treatment

A
  • vacuolar form in stool
    PCR test

Treatment: metronidazole

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13
Q

Hookworm: patho and clinical features

A

Ancyclostoma duodenale
Necator americanus

filariform larva penetrates skin –> ground itch, erythematous papular rash, Loeffler’s syndrome (cough, dyspnea, hyper-eosinophilia), black stool

Chronically: leads to iron deficiency microcytic hypochromic anemia

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14
Q

Hookworm: Lab diagnosis and treatment

A
  • microsopy, stool culture , morphology

Mebendazole/ albendazole, iron supplement

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15
Q

Trichuris trichiura: patho

A

whipworm in large intestine (cecum and ascending colon)
anterior portion - thin and thread-like (straight tip if female, rounded tip if male)
posterior portion – thick and fleshy

Anterior part embeds into mucosa of large intestine

egg: barrel-shaped, bipolar plugs, unsegmented ovum

oral fecal route

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16
Q

Trichuris trichiuria: clinical features

A

usually asymptomatic

anemia, malnutrition

mucus diarrhea, chronic dysentery, abd pain, rectal prolapse (young children)

17
Q

Trichuris trichiuria: lab diagnosis, prevention and treatment

A

barrel shaped egg, bipolar plug in stool

adult worms in mucosa

prevention: good hygiene

Mebendazole, Albendazole, Ivermectin

18
Q

Ascaris lumbricoides

A
  • small intestine
  • has three prominent lips
  • male is bigger than female
19
Q

Ascaris lumbricoides: larval migration phase

A

infiltration of eosinophils and macrophages

loeffler’s syndrome: low grade fever, cough, wheezing, dyspnea, transient eosinophilia, lung infiltration

20
Q

Ascaris lumbricoides: intestinal phase of adult worms

A

usually asymptomatic, can cause intestinal obstruction/ malnutrition

Ectopic migration to
- blocks pancreatic ducts : pancreatitis
- liver parenchyma -> liver abscess
- up oesophagus, leaves through mouth/ nose
- obstructs appendix –> appendicitis
- perforates intestines –> peritonitis

21
Q

Ascaris lumbricoides: lab diagnosis, prevention and treatment

A

detection of eggs in stool
adult worms in feces/ vomit
larvae in sputum/ gastric aspirate

prevention: good hygiene

treatment: pyrantel pamoate

22
Q

Enterobius vermicularis:

A

pinworm –> enterobiasis
Adults usually in cecum and appendix
egg: D shaped, flattened on one side

oral fecal route

23
Q

Enterobius vermicularis: patho, clinical features

A

eggs: sticky and sticks to perianal skin

ectopic migration:
1. vulva and vagina : irritation and inflammation
2. uterus and fallopian tubes: cervicitis and chronic salpinitis

retroinfection: eggs laid on perianal skin hatch into infective stage larva–> migrates through anus, develops into worms at colon

24
Q

Enterobius vermicularis: lab diagnosis and treatment

A

cellophane tape/ scotch tape method

Mebendazole, Albendazole, Piperazine, Pyrantel

25
Q

Schistosomiasis patho and clinical features

A

snail fever, water borne
Schistosoma japonicum, mansoni, haematobium

  • penetrates skin
  1. local cercarial dermatitis (swimmer’s itch)
    - itching and petechial lesions
  2. acute schistosomiasis (Katayama fever)
    - hypersensitivity reaction (fever, cough, abd pain, diarrhea, hepatosplenomegaly, eosinophilia)
  3. oviposition of S. haematobium
    - painless terminal haematuria,

could lead to squamous cell carcinoma of bladder

eggs: carried to liver –> hepatosplenomegaly, periportal fibrosis, portal hypertension

S. mansoni, S. japonicum eggs
- inflammatory reaction (granulomas, hyperplasia, fibrosis)

26
Q

Schistosomiasis: lab diagnosis and treatment

A

eggs in feces/ urine
- praziquantel

27
Q

Taenia saginata (beef), Taenia solium (pork)

A

flat segmented worms
adult worms: head (scolex attaches to intestine), neck, chain of segments

28
Q

T saginata, T solium: patho and clinical features

A

mostly asymptomatic
- vague abd discomfort, indigestion, nausea, diarrhea, weight loss
- acute intestinal obstruction, acute appendicitis

Cysticercosis
- seizures, muscle/ eye damage
- development of larva (cysticercus cellulosae)
- eggs –> larvae–> migrate to organ/ tissue: subcutaneous tissues, brain, eye
- neurocysticercosis (brain): headache, seizures due to reaction to dead worms

SEM 3 Bacteria, Parasites, Viruses GI (3 decks)

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