What Is Traveller's Diarrhoea

Overview

Traveller’s diarrhoea is a common illness among people travelling to resource-limited destinations overseas. It affects around 40% to 60% of travellers, depending on the place they travel. This condition can be due to bacterial, viral, and parasitic infections, though bacterial sources represent the most frequent cause. While traveller’s diarrhoea is usually harmless and resolves on its own, it can lead to dehydration and, in severe cases, considerable complications.¹

Traveller’s diarrhoea is typically defined as the passage of ≥ 3 unformed stools per 24 hours plus at least one additional symptom (such as nausea, vomiting, abdominal cramps, fever, blood or mucus in the stools, or a sudden need to use the bathroom) that begin while abroad or within 10 days of arriving back from any place with limited resources. In children, traveller’s diarrhoea is defined as a ≥ 2-fold increase in the frequency of unformed stools instead of ≥ 3 unformed stools per 24 hours.²

Causes

The most frequent bacterial cause is Enterotoxigenic Escherichia coli (ETEC). Other common bacteria that lead to traveller’s diarrhoea include Campylobacter jejuni, Shigella, and Salmonella species.¹

Norovirus is the most common viral cause, while rotavirus is another reason for infection. Giardia intestinalis is the most usual parasitic source, while Cryptosporidium and Entamoeba histolytica can also give rise to traveller’s diarrhoea.¹

Traveller's diarrhoea can develop in both short- and long-term travellers, and generally, there is no immunity against future attacks.¹ 

Occurrence and risk factors

The occurrence and causative agent of traveller’s diarrhoea differ by destination, with the highest incidence reported in sub-Saharan Africa. Other locations with high prevalence include Latin America, the Middle East, and South Asia.¹

Risk factors are usually related to poor sanitation in resource-limited areas. These include¹:

• Poor hygienic practices in food handling and preparation
• Inadequacy of refrigeration
• Deficient food storage practices

Further modifiable risk factors include:¹

• Proton pump inhibitor use
• Recent antibiotic utilisation
• Unsafe sexual practices

Risk factors for severe complications of traveller’s diarrhoea are¹:

• Pregnancy
• Young or old age
• Travellers with underlying chronic gastrointestinal diseases, or people who have a weakened immune system. 

Source spread

Traveller’s diarrhoea is typically acquired through the consumption of food or water contaminated by stool. Sometimes, traveller’s diarrhoea may be acquired by handling contaminated objects or from accidental swallowing of contaminated water from swimming pools and other recreational water sources. Insects, especially flies, are important vectors for some germs in food that cause intestinal illness.²

Symptoms

Both bacterial and viral traveller’s diarrhoea present with the sudden onset of troublesome symptoms that can span from mild cramps and urgent loose stools to severe abdominal pain, bloody diarrhoea, fever, and vomiting; with norovirus, vomiting can be more notable. Diarrhoea caused by a parasitic source such as Entamoeba histolytica usually has a more gradual onset of mild symptoms, with 2–5 loose stools per day.³

Complications         

Complications of traveller’s diarrhoea include:²

• Dehydration
• Sepsis
• Hemolytic-uremic syndrome
• Postinfectious irritable bowel syndrome
• Clostridium difficile colitis
• Guillain-Barré syndrome
• Reactive arthritis
• Acute myocarditis
• Permanent short-term memory loss

Diagnosis

The diagnosis of traveller’s diarrhoea is mainly made based on the history of passage of more than or equal to 3 unformed stools per 24 hours, plus at least one additional symptom (such as nausea, vomiting, abdominal cramps, fever, blood or mucus in the stools, or urgency to use the bathroom) that develops while being outside the country or within 10 days of returning from travel to a resource-limited setting.²

Typically, there's no need for laboratory tests unless the patient shows signs of being seriously ill, such as having a high fever, being hospitalised, experiencing bloody or cholera-like diarrhoea, having intense abdominal cramps, a weakened immune system, a major existing health issue, or if diarrhoea persists despite initial treatment attempts.²

Prevention

General tips

The following tips may help reduce the risk of developing traveller’s diarrhoea:⁴

• Wash hands regularly, especially before eating and after going to the bathroom.
• Avoid touching the face with the hands if they haven't been washed.
• Have disinfectant wipes or gels at the ready in case it isn't possible to wash hands while out and about. Dry the hands with disposable paper towels, if available.
• Avoid consuming tap water. Opt for water from sealed bottles or other secure containers. Steer clear of ice cubes and drinks that may be diluted with water.
• Use bottled water to brush the teeth and rinse the mouth.
• Avoid consuming water from fountains, wells, streams, rivers, springs, waterfalls, or stagnant water sources.
• Fruits, raw vegetables, lettuce, and herbs should only be consumed if they are peeled or thoroughly washed with bottled water.
• Don't eat undercooked meat or fish.
• Steer clear of interacting with animals, as they too can transmit bacteria or viruses.
• Keep flies away from food.

Antibiotics

Preventive therapy using antibiotics should not be routinely employed for several reasons, including the potential alteration of the intestinal flora, the development of adverse events, the development of antibiotic resistance, possible drug interactions, and the cost of the medication.²

Consider implementing preventive antibiotic therapy for individuals who cannot afford to fall ill, such as politicians or elite athletes. Additionally, it should be extended to those with a higher susceptibility to traveller’s diarrhoea and an elevated risk of severe complications. This includes individuals who are elderly, possess a weakened immune system, are prone to complications from diarrhoea, or suffer from chronic illnesses like inflammatory bowel disease, short bowel syndrome, gastric hypochlorhydria, congestive heart failure, diabetes mellitus, or chronic renal failure.²

If necessary, this therapy should be short-term. It should not exceed 14 days. Rifaximin is the drug of choice for the prevention of traveller’s diarrhoea and is deemed effective and safe. Bismuth subsalicylate could also be an option to prevent traveller’s diarrhoea.²

Vaccines

Generally, it is advisable to determine the recommended vaccinations in the country or region to which travel is planned before departure. ⁴

Individuals visiting regions with a high risk of cholera are recommended to receive a cholera vaccine. ⁴
Vaxchora, a single-dose oral cholera vaccine, is the only vaccine approved for preventing cholera by the Food and Drug Administration. The vaccine is recommended for adults 18 to 64 years of age travelling to areas where cholera is prevalent or indigenous and should be considered for those who are at high risk of exposure. Vaxchora is well tolerated and free from any notable adverse effects.²

The typhoid vaccine is advised for travellers heading to areas with inadequate sanitation. There are two main global options: the inactivated Vi Capsular Polysaccharide vaccine (ViCPS) given through injection and the oral live-attenuated vaccine, Ty21a.²

For the inactivated vaccine (ViCPS), just one intramuscular dose is needed, administered at least two weeks before travel. On the other hand, the oral vaccine (Ty21a) requires four doses given two days apart, with the last dose at least one week before travel. ViCPS is approved for individuals aged 2 years and older, while Ty21a is licensed for those aged 5 years and older.²

The newly introduced Tybar-TCV typhoid vaccine is administered through a single intramuscular injection at least two weeks before travel. The vaccine has demonstrated safety, good tolerance, and efficacy. Recently, the World Health Organization (WHO) has recommended Tybar-TCV as the preferred vaccine for preventing typhoid fever.²

Treatment

The basis of diarrhoea management is hydration. For mild cases, travellers should prioritise higher water intake. Water alone is generally effective, but sports drinks and other electrolyte fluids can also be beneficial. It's important to avoid milk and juices, as they may exacerbate diarrhoea. In more severe situations, oral rehydration salt can be employed to ensure proper rehydration and electrolyte repletion. In instances of severe dehydration, intravenous fluids may become necessary.¹

Treatment is supportive in mild-to-moderate cases. For individuals experiencing non-inflammatory diarrhoea symptoms, loperamide can be employed to alleviate discomfort. The recommended dosage for adults is an initial 4 mg, followed by 2 mg after each subsequent loose stool, with a maximum daily limit of 16 mg.¹
Ciprofloxacin is a frequently used antibiotic for treatment, but there are concerns about resistance, particularly with Campylobacter species. As a result, this type of antibiotic is not commonly recommended for travellers to Asia, and azithromycin is preferred. Azithromycin is also a common choice for pregnant travellers and children. A typical prescription involves taking 500 mg daily for three days. Rifaximin, another antibiotic that is minimally absorbed, is an alternative option considered safe for older children and pregnant travellers.¹

Role of probiotics

Probiotics like Lactobacillus rhamnosus GG, Lactobacillus acidophilus, and Saccharomyces boulardii are employed in both the treatment and prevention of traveller’s diarrhoea. This is due to their positive impact on intestinal flora, leading to the suppression of harmful bacteria.²

Utilising probiotics to prevent traveller's diarrhoea offers several benefits, such as convenient availability, the absence of antibiotic resistance, and mild adverse events.⁵
In a 2018 study, researchers found that probiotics can help prevent traveller's diarrhoea. However, the study didn't tell us which specific probiotics or probiotic combinations work best for preventing this type of diarrhoea. This is something that both doctors and people who travel have been curious about for a while.⁵

Concluding remarks

• Traveller’s diarrhoea is a prevalent concern, affecting 40% to 60% of individuals visiting resource-limited destinations, with bacterial sources being the most common cause.
• Incidence and causative agents vary by destination, with sub-Saharan Africa reporting the highest occurrence. 
• Risk factors are linked to inadequate sanitation, including poor food handling, inadequate refrigeration, and deficient food storage practices.
• Consumption of contaminated food or water is the primary mode of transmission, but handling contaminated objects can also contribute.
• Bacterial and viral traveller's diarrhoea manifests with abrupt and distressing symptoms, ranging from mild cramps to severe abdominal pain, while parasitic-induced diarrhoea typically exhibits a slower onset of milder symptoms.
• Complications include dehydration, sepsis, hemolytic-uremic syndrome, and others.
• Diagnosis is based on symptoms, and laboratory tests are generally unnecessary unless severe signs are present.
• Travellers to high-risk areas should be counselled on self-diagnosis and treatment of travellers’ diarrhoea.
• Preventive measures include hand hygiene, avoiding tap water, and safe food practices.
• Preventive antibiotic therapy is not routinely recommended due to potential drawbacks, except for high-risk individuals. Rifaximin is the drug of choice for short-term prevention.
• Vaccinations, including cholera and typhoid vaccines, are recommended based on travel destinations.
• Hydration is the cornerstone of diarrhoea management, with oral rehydration salts for severe cases. Loperamide and antibiotics like azithromycin or rifaximin are used in treatment.
• Probiotics, known for their beneficial effects on intestinal flora, are used to treat and prevent traveller's diarrhoea; however, the specific probiotic strains for optimal prevention are still uncertain.

Summary

Traveller's diarrhoea is a common issue affecting 40% to 60% of those visiting resource-limited areas, primarily caused by bacterial infections like ETEC and viral infections like norovirus. Poor sanitation and contaminated food and water contribute to its spread, with symptoms ranging from mild to severe, including dehydration and potential complications like sepsis or reactive arthritis. Diagnosis relies on symptoms, with antibiotics like azithromycin or rifaximin used for treatment in severe cases. Preventive measures like hand hygiene and avoiding tap water are crucial, while vaccines for cholera and typhoid are recommended for high-risk areas. Probiotics show promise in prevention, although optimal strains remain uncertain.