Traveller’s diarrhoea is caused by:
**Core Concept**
Traveller's diarrhoea is a common condition caused by the ingestion of contaminated food or water, leading to an imbalance in the gut microbiota and subsequent inflammation. The primary culprits behind this condition are enteric pathogens, which can compromise the intestinal barrier function and disrupt normal gut motility.
**Why the Correct Answer is Right**
The correct answer is related to the most common cause of traveller's diarrhoea, which is the enteric pathogen *Escherichia coli* (E. coli). Specifically, the pathogenic strains of E. coli, such as Enterotoxigenic E. coli (ETEC), produce heat-stable and heat-labile toxins that stimulate the intestinal epithelial cells to secrete water and electrolytes, resulting in diarrhoea. This mechanism is mediated through the activation of guanylate cyclase and the subsequent increase in cyclic GMP levels.
**Why Each Wrong Option is Incorrect**
**Option A:**
*This option is not a correct answer as it is a broad category of pathogens, and while some viruses can cause diarrhoea, they are not the primary cause of traveller's diarrhoea.*
**Option B:**
*This option is incorrect as *Salmonella* species can cause traveller's diarrhoea, but they are not the most common cause.*
**Option C:**
*This option is not a correct answer as *Campylobacter* species are a common cause of diarrhoeal disease, but they are more commonly associated with food poisoning rather than traveller's diarrhoea.*
**Clinical Pearl / High-Yield Fact**
The most effective prevention strategy for traveller's diarrhoea is the use of a combination of vaccines, such as the oral cholera vaccine, and antibiotics, such as rifaximin, which can be used to reduce the duration and severity of diarrhoeal episodes.
**Correct Answer: B. Salmonella**