HTHSCI 1DT3 Lecture Notes - Lecture 21: Pathogenicity Island, Intestinal Parasite Infection, Tinidazole
23 Jun 2018
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Traveller’s Diarrhoa
= 3+ loose stools +/- systemic symptoms in a traveller
- Travel can include urban rural movement
Important to identify as all are notifiable diseases
Occurs 5-15 days post-travel
Commonest health problem to afflict travellers
50% who travel to a tropical climate will get it in the first 1-2 weeks
Highest risk at Asian subcontinent, S. America, Africa
Commoner in <25yo (perhaps due to behavioural factors)
Possible host mutation affect it e.g. presence of lactoferrin mutations (secreted in saliva) may
increase risk – Mohamed et al 2007
Normally a self-limiting illness, though sometimes symptoms persist for over one month
BP, presence of fever and dehydration (low BP, postural drop in BP, mucous membranes, cap
refill) are key signs
Diarrhoea / fever can be sign of another septic illness e.g. liver abscess: caution in excluding
serious pathology
Exclude a surgical abdomen
Causes of TD
1) E.coli
2) Campylobacter
3) Non-typhoid salmonella
4) Shigella
5) Viruses (noro and rotavirus)
6) Giardia, entamoeba
Other rare = strogyloidiasis, aeromonas, yersinia etc.
E.Coli
Gram -, non-spore forming motile rod
Commonest bacteria in the healthy gut; a variety have virulence factors whch make them
pathogenic
Cause diarrhoea by 5 mechanisms
Must do PCR to detect virulence factors, thus difficult to diagnose, as normal culture will always
be positive due to commensals only done routinely for EHEC
Enterotoxigenic E.Coli (ETEC)
Commonest E.Coli
Frequent cause of TD and childhood diarrhoeal outbreaks
Faecal-oral transmission
Watery diarrhoea, nausea and cramps
Incubation period of 0-46hours; symptoms only occur for 5 days
Causes diarrhoea through heat labile toxin (like cholera toxin) and heat stable toxin
- Heat labile toxin:
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Document Summary
= 3+ loose stools +/- systemic symptoms in a traveller. Travel can include urban rural movement. Important to identify as all are notifiable diseases. 50% who travel to a tropical climate will get it in the first 1-2 weeks. Highest risk at asian subcontinent, s. america, africa. Commoner in <25yo (perhaps due to behavioural factors) Possible host mutation affect it e. g. presence of lactoferrin mutations (secreted in saliva) may increase risk mohamed et al 2007. Normally a self-limiting illness, though sometimes symptoms persist for over one month. Bp, presence of fever and dehydration (low bp, postural drop in bp, mucous membranes, cap refill) are key signs. Diarrhoea / fever can be sign of another septic illness e. g. liver abscess: caution in excluding serious pathology. Causes of td: e. coli, campylobacter, non-typhoid salmonella, shigella, viruses (noro and rotavirus, giardia, entamoeba. Commonest bacteria in the healthy gut; a variety have virulence factors whch make them pathogenic.
