Intestinal parasites Flashcards
1
Q
Intestinal parasites - overview
A
- Infection usually via fecal-oral route
- Pets and livestock can be hosts
- Can mimic IBD, hepatitis, sclerosing cholangitis, peptic ulcer disease and celiac disease
2
Q
Intestinal parasites - list
A
A. Protozoa (unicellular eukaryotic organisms) - 3
- Giardia lamblia
- Entamoeba histolytica
- Cryptosporidium
B. Nematodes (roundworms)
- Ascaris lumbicoides
- Trichuris trichiura (whip worm)
- Hookworms (Necator americanus, Ancylostoma duodenale)
- Strongyloides stercoralis
- Enterobius vermicularis (thread or pinworm)
C. Cestodes (tapeworms)
3
Q
Intestinal parasites - presentation (general)
A
- Abdominal pain
- Diarrhoea, dysentery, flatulence, abdominal distension, intestinal obstruction
- Malabsorption + FTT
- Biliary obstruction, liver disease, pancreatitis
- Fever
4
Q
Intestinal parasites - ix
A
- Stool MCS for ova, cysts, parasites and leukocytes
- Specific stool staining for cryptosporidiosis
- Stool ELISA for giardiasis and cryptosporidiosis
- Blood specific serology, e.g. entamoeba histolytica
- Duodenal fluid aspiration for MCS, duodenal villus biopsy
5
Q
Giardia lamblia - overview (3)
A
- Very common - swallowed cysts develop into trophozoites that attach to the small intestinal villi, causing mucosal damage
- Presentation = diarrhoea, flatulence, abdominal discomfort, sometimes FTT
- Mx = tinidazole orally or metronidazole orally
6
Q
Entamoeba histolytica - overview (3)
A
- Symptoms usually mild
- But may cause fulminating colitis (amoebic dysentery may mimic UC), intestinal obstruction due to chronic localised lesion (an ‘amoeboma’), amoebic hepatitis, liver abscess (RUQ pain, fever, hepatomegaly)
- Mx = tinidazole orally, or metronidazole orally (if acute amoebic colitis [dysentery])
7
Q
Cryptosporidium - overview (3)
A
- Causes a mild self-limiting illness
- Except in immunocompromised pts, where it can cause severe chronic watery diarrhoea, flatulence, malaise, abdominal pain and weight loss
- Mx = nitazoxanide orally + fluid and electrolyte therapy + antidiarrhoeal drugs + tx underlying cause of immunocompromise
8
Q
Ascaris lumbricoides - overview (3)
A
- Most common parasitic worm infection in humans; up to 25% of world’s population infected
- Heavy infestation can cause specific nutritional deficiencies or bowel obstruction
- Mx = albendazole orally, mebendazole orally or pyrantel orally
9
Q
Trichuris trichiura (whip worm) - overview (3)
A
- Lives in the colon
- Causes diarrhoea, abdominal pain and weight loss
- Mx = albendazole orally, mebendazole orally
10
Q
Hookworms (Necator americanus, Ancylostoma duodenale) - overview (3)
A
- Infection by larvae penetrating the skin, e.g. bare feet
- Adult worms live in the intestine, voraciously sucking blood, leading to anaemia and hypoproteinaemia
- Mx = albendazole orally, mebendazole orally or pyrantel orally
11
Q
Strongyloides stercoralis - overview (3)
A
- Penetrates the skin and migrates to the lungs, then coughed up and ingested into the gut
- Causes bloating, heartburn and malabsorption
- Mx = ivermectin orally, or albendazole orally
12
Q
Enterobius vermicularis (thread/pinworm) - overview (3)
A
- Very common; causes anal pruritus as females emerge and lay eggs in peri-anal region
- Dx = confirmed by direct visualisation of worms on perianal area or in stool, or by microscopy of sellotape previously applied to anus
- Mx = mebendazole orally, or albendazole orally, or pyrantel orally
13
Q
Cestodes (tapeworms) - overview (3)
A
- Infection results from ingesting undercooked contaminated pork, beef or fish
- Dx by microscopy of eggs or proglottids (segments of tapeworm) in stool
- Mx:
- Taenia solium (pork tapeworm), or if species unknown = niclosamide orally
- Taenia saginata (beef tapeworm) = praziquantel orally, or niclosamide orally
