Tropical infections of GI tract Flashcards

1
Q

describe the history you would want to acquire in a returned traveller with a fever?

A

1) where have they been?
- rural/urban
- accommodation situation

2) when did they go & when did they get back?

3) what did they do when they went away?
- swimming, animal contact, walking in bushes, sex, work

4) when did they start becoming unwell?
5) did they have any insect bites - tick bites?

6) what are their symptoms?
+ is anyone else unwell?

7) vaccines, malaria prophylaxis, bite protection, condoms

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2
Q

what 5 things do you need to think about when someone presents with a fever who is a returned traveller?

A
  • resp tract infections
    = pneumonia/influenza
  • travellers’ diarrhoea
  • malaria
  • enteric fever
  • arboviruses
    = dengue, Chikungunya, zika
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3
Q

what would you do with somebody who presents with a fever who is a returned traveler?

A

= infection control
- isolate all returns travellers until clinical picture is clear
+ use PPE

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4
Q

what is acute traveller’s diarrhoea?

A

= 3 loos stools in 24hours

+ fever

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5
Q

what typically causes acute traveller’s diarrhoea?

A

= enterotoxigenic E. coli

But also;
= campylobacter, salmonella, shigella

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6
Q

what 2 viruses are common on cruise ships?

A
  • norovirus

- rotavirus

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7
Q

what are possible causes of bloody diarrhoea (dysentry) and profuse watery diarrhoea?

A

Bloody diarrhoea
= E. coli 0157 + amoebic colitis

Profuse watery diarrhoea
= cholera
= toxin mediated disease often associated with outbreaks (refugee camps)

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8
Q

how would you investigate acute traveller’s diarrhoea?

A

1) stool culture

2) stool wet prep on recently passed stool for amoebic trophozoites

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9
Q

how would you treat someone with acute traveller’s diarrhoea?

A
  • supportive
    = fluid dehydration
  • bloody diarrhoea with systemic upset may warrant treatment
  • in those travelling a FLUOROQUINOLONE (ciprofloxacin) single dose can stop worsening)
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10
Q

what are 2 types of enteric fever?

A

1) typhoid

2) paratyphoid

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11
Q

who is most likely to acquire an enteric fever?

A

= in those returning from Indian sub-continent and SE Asia (often those visiting family or friends)

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12
Q

describe the incubation period for enteric fever?

A

7-18days

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13
Q

what are symptoms of enteric fever?

A
  • fever
  • non-specific
    = headache
    = constipation or diarrhoea
    = dry cough
- complications 
= GI bleeding 
= GI perforation 
= encephalopathy 
= bone and joint infection
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14
Q

what is enteric fever most commonly caused by?

A

= salmonella typhi or paratyphi

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15
Q

describe how you would deal with salmonella typhi or paratyphi?

A
  • treat empirically if patient is unstable withIV ceftriaxone
  • fever clearance time
    = ciprofloxacin <4days
    = azithromycin 4.4days
    = ceftriaxone 6.2 days
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16
Q

what precautions should be taken in people with enteric fever?

A

Precautions

  • water
  • food
  • hand hygiene

Vaccinations
- incomplete protection against s. typhi no protection against S. paratyphi

hospital
= isolate patients immediately if diagnosis is considered

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17
Q

what are 3 types of fever and jaundice?

A

1) pre-hepatic (haemolytic)
2) hepatic
3) post-hepatic

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18
Q

what could be the cause of pre-heptic fever & jaundice?

A
  • malaria
  • HUS as complication of diarrhoea illness = E. coli 0157, shigella
  • sickle cell crisis triggered by infection
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19
Q

what could be some causes of hepatic causes of fever and jaundice?

A
  • Hepatitis A and E – acute (occasionally Hepatitis B)
  • Leptospirosis – Weils diseases (Icteric, haemorrhagic and renal failure)
  • Malaria
  • Enteric fever
  • Rickettsia (scrub typhus, Rocky Mountain spotted fever etc)
  • Viral haemorrhagic fever
20
Q

what could be the cause of post-hepatic fever and jaundice?

A
  • associated cholangitis and helminths
21
Q

how would you investigate anyone with fever & jaundice?

A
  • Malaria blood film and rapid antigen
  • Blood film for red cell fragmentation
  • FBC/UE/LFT/coagulation
  • Blood cultures
  • USS abdomen
  • Serological testing for viruses
22
Q

how would you manage anyone with fever & jaundice?

A
  • isolation & infection control
  • Supportive – may need dialysis if acute kidney injury
  • If acute liver failure – hepatology/transplant unit
  • Directed to pathogen isolated
  • Discussion with infectious diseases
23
Q

what is a common cause of amoebiasis?

A

= entamoeba histolytica, a protozoa

24
Q

how is entamoeba histolytica, a cause of amoebiasis spread?

A

= faecal-oral spread, strong association with poor sanitation

25
Q

describe symptoms of entamoeba histolytica?

A

= asymptomatic carriage
- shed cysts in stools chronically

- amoebic dysentry 
= fever
= abdominal pain 
= blood diarrhoea/colitis 
= toxic and unwell, abdominal tenderness, peritonism
26
Q

how would you investigate entamoeba histolytica?

A
  • Stool microscopy for trophozoites or cysts (distinguish between E. histolytica and E. dispar)
  • AXR - ?toxic megacolon
  • Endoscopy for biopsy (not if evidence of toxic dilatation)
27
Q

describe the incubation period of amoebic liver abscesses?

A

= 8-20weeks

  • more common in men
28
Q

describe the sub-acute presentation over 2-4weeks of amoebic liver abscesses?

A
  • fever, sweats
  • upper abdominal pain
  • sometimes history of GI upset (dysentry)
  • hepatomegaly
  • point tenderness over right lower rises
29
Q

what investigations should be done in people with amoebic liver abscesses?

A
  • Abnormal LFTs
  • CXR – raised right hemi-diaphragm
  • USS/CT scan
  • Serology
  • Stool microscopy - often negative (E. histolytica looks similar to E.dispar)

= exclude hydatid disease before aspiration if from high risk country (Middle East, Central Asia)

30
Q

how would you manage amoebic liver abscesses?

A
  • metronidazole or trindazole
  • If pyogenic abscess a possibility, treat with appropriate antibiotics whilst awaiting diagnostic investigations.
  • Need to clear the gut lumen of parasites
    = Paramomycin/diloxanide
31
Q

what is a likely cause of giardiasis?

A

= giarida intestinal (lamblia), flagellated protozoa

32
Q

what does giarida intestinal invade?

A

= duodenum ad proximal jejunum

33
Q

how is giarida intestinal spread?

A

= faecal-oral spread (contaminated water most commonly)

34
Q

what is the incubation period for giarida intestinal?

A
  • around 7 days
35
Q

how would you present with giarida intestinal?

A

= watery, malodorous diarrhoea
= bloating, flatulence
= abdominal cramps
= weight loss

36
Q

how would you investigate giarida intestinal?

A
  • stool microscopy for crypts, in developed world PCR tests

- OGD for duodenal biopsy

37
Q

how would you treat giarida intestinal?

A
  • metronidazole or tinidazole
38
Q

what type of pathogen is a helminth?

what are 3 types of helminths?

A

= a parasite

  • Nematodes (Roundworms)
    = Intestinal roundworms
    = Tissue roundworms (filariasis)
  • Trematodes (Flukes)
  • Cestodes (Tapeworms)
    = Intestinal
    = Larval
39
Q

where would you find helminth infections?

A

= in gut, in tissues

  • often associated with eosinophils
40
Q

how are helminth infections often diagnosed?

A

= by adult worm passed or in the eggs in stool

41
Q

describe the lifecycle of intestinal nematode helminth infections?

A
  • Egg ingested – hatch in small intestine
  • invade gut wall into venous system and via liver and heart reach lungs
    = break into alveoli
  • ascend tracheobroncial tree then swallowed and in the gut develop into adult worm where they start to produce eggs.
42
Q

what do trematodes, flukes, a type of helminth cause?

A

= schistosomiasis
- fresh water exposure

  • acute infection
  • chronic infection (adult worm located in portal venues leads to hepatomegaly and liver fibrosis and portal hypertension)
43
Q

what can liver flukes cause?

A

= clonorhcis/fasciola

SE asia

44
Q

what can cestodes, tapeworms, a type of helminth cause?

A
  • Taenia solium (Pork) or saginatum (Beef)
    = acquired by eating undercooked meat containing infectious larval cysts
  • Taenia solium eggs (autoinoculation or from human faeces)
    = cause cysticercosis – tissue cysts muscle and brain (neurocystercercosis) often producing seizures
45
Q

what causes chaggas disease?

A

= Trypanasoma cruzi – Amercian Trypanosmiasis

46
Q

how is chaggas disease transmitted?

A

= by kissing bug (triatome)

47
Q

what does chaggas disease cause?

A

= parasympathetic denervations effecting colon and oesophagus
= megaoesophagus