Tropical infections of GI tract Flashcards
describe the history you would want to acquire in a returned traveller with a fever?
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
what 5 things do you need to think about when someone presents with a fever who is a returned traveller?
- resp tract infections
= pneumonia/influenza - travellers’ diarrhoea
- malaria
- enteric fever
- arboviruses
= dengue, Chikungunya, zika
what would you do with somebody who presents with a fever who is a returned traveler?
= infection control
- isolate all returns travellers until clinical picture is clear
+ use PPE
what is acute traveller’s diarrhoea?
= 3 loos stools in 24hours
+ fever
what typically causes acute traveller’s diarrhoea?
= enterotoxigenic E. coli
But also;
= campylobacter, salmonella, shigella
what 2 viruses are common on cruise ships?
- norovirus
- rotavirus
what are possible causes of bloody diarrhoea (dysentry) and profuse watery diarrhoea?
Bloody diarrhoea
= E. coli 0157 + amoebic colitis
Profuse watery diarrhoea
= cholera
= toxin mediated disease often associated with outbreaks (refugee camps)
how would you investigate acute traveller’s diarrhoea?
1) stool culture
2) stool wet prep on recently passed stool for amoebic trophozoites
how would you treat someone with acute traveller’s diarrhoea?
- supportive
= fluid dehydration - bloody diarrhoea with systemic upset may warrant treatment
- in those travelling a FLUOROQUINOLONE (ciprofloxacin) single dose can stop worsening)
what are 2 types of enteric fever?
1) typhoid
2) paratyphoid
who is most likely to acquire an enteric fever?
= in those returning from Indian sub-continent and SE Asia (often those visiting family or friends)
describe the incubation period for enteric fever?
7-18days
what are symptoms of enteric fever?
- fever
- non-specific
= headache
= constipation or diarrhoea
= dry cough
- complications = GI bleeding = GI perforation = encephalopathy = bone and joint infection
what is enteric fever most commonly caused by?
= salmonella typhi or paratyphi
describe how you would deal with salmonella typhi or paratyphi?
- treat empirically if patient is unstable withIV ceftriaxone
- fever clearance time
= ciprofloxacin <4days
= azithromycin 4.4days
= ceftriaxone 6.2 days
what precautions should be taken in people with enteric fever?
Precautions
- water
- food
- hand hygiene
Vaccinations
- incomplete protection against s. typhi no protection against S. paratyphi
hospital
= isolate patients immediately if diagnosis is considered
what are 3 types of fever and jaundice?
1) pre-hepatic (haemolytic)
2) hepatic
3) post-hepatic
what could be the cause of pre-heptic fever & jaundice?
- malaria
- HUS as complication of diarrhoea illness = E. coli 0157, shigella
- sickle cell crisis triggered by infection
what could be some causes of hepatic causes of fever and jaundice?
- 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
what could be the cause of post-hepatic fever and jaundice?
- associated cholangitis and helminths
how would you investigate anyone with fever & jaundice?
- Malaria blood film and rapid antigen
- Blood film for red cell fragmentation
- FBC/UE/LFT/coagulation
- Blood cultures
- USS abdomen
- Serological testing for viruses
how would you manage anyone with fever & jaundice?
- 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
what is a common cause of amoebiasis?
= entamoeba histolytica, a protozoa
how is entamoeba histolytica, a cause of amoebiasis spread?
= faecal-oral spread, strong association with poor sanitation
describe symptoms of entamoeba histolytica?
= asymptomatic carriage
- shed cysts in stools chronically
- amoebic dysentry = fever = abdominal pain = blood diarrhoea/colitis = toxic and unwell, abdominal tenderness, peritonism
how would you investigate entamoeba histolytica?
- 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)
describe the incubation period of amoebic liver abscesses?
= 8-20weeks
- more common in men
describe the sub-acute presentation over 2-4weeks of amoebic liver abscesses?
- fever, sweats
- upper abdominal pain
- sometimes history of GI upset (dysentry)
- hepatomegaly
- point tenderness over right lower rises
what investigations should be done in people with amoebic liver abscesses?
- 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)
how would you manage amoebic liver abscesses?
- 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
what is a likely cause of giardiasis?
= giarida intestinal (lamblia), flagellated protozoa
what does giarida intestinal invade?
= duodenum ad proximal jejunum
how is giarida intestinal spread?
= faecal-oral spread (contaminated water most commonly)
what is the incubation period for giarida intestinal?
- around 7 days
how would you present with giarida intestinal?
= watery, malodorous diarrhoea
= bloating, flatulence
= abdominal cramps
= weight loss
how would you investigate giarida intestinal?
- stool microscopy for crypts, in developed world PCR tests
- OGD for duodenal biopsy
how would you treat giarida intestinal?
- metronidazole or tinidazole
what type of pathogen is a helminth?
what are 3 types of helminths?
= a parasite
- Nematodes (Roundworms)
= Intestinal roundworms
= Tissue roundworms (filariasis) - Trematodes (Flukes)
- Cestodes (Tapeworms)
= Intestinal
= Larval
where would you find helminth infections?
= in gut, in tissues
- often associated with eosinophils
how are helminth infections often diagnosed?
= by adult worm passed or in the eggs in stool
describe the lifecycle of intestinal nematode helminth infections?
- 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.
what do trematodes, flukes, a type of helminth cause?
= schistosomiasis
- fresh water exposure
- acute infection
- chronic infection (adult worm located in portal venues leads to hepatomegaly and liver fibrosis and portal hypertension)
what can liver flukes cause?
= clonorhcis/fasciola
SE asia
what can cestodes, tapeworms, a type of helminth cause?
- 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
what causes chaggas disease?
= Trypanasoma cruzi – Amercian Trypanosmiasis
how is chaggas disease transmitted?
= by kissing bug (triatome)
what does chaggas disease cause?
= parasympathetic denervations effecting colon and oesophagus
= megaoesophagus
