What is traveller's diarrhoea?

Have you ever envisioned the perfect summer getaway, with dreams of lush greenery and pristine white beaches, only for it to be derailed by some of the tiniest of organisms? Traveller’s diarrhoea is the most common travel-related illness, affecting around 40-60% of travellers to the tropical and subtropical regions, with variations in the incidence depending on the place and season of travel. It is an unpleasant gut infection caused mostly by bacteria, but sometimes by viruses and parasites.¹ The infection is spread via contaminated food, water and cutlery, due to poor hygienic practices.² Traveller’s diarrhoea typically resolves on its own after 3-5 days, but can cause significant complications, including dehydration in some. Oral Rehydration Solutions (ORS) can ensure that you are hydrated adequately throughout the illness with adequate repletion of electrolytes.¹ This article will dive into how traveller’s diarrhoea occurs, how it can get complicated by dehydration and the role of ORS in the management of the illness.

How does traveller’s diarrhoea occur?

Traveller’s diarrhoea is spread faeco-orally via contaminated food, water, or utensils. Lack of clean water, shortcuts in cleaning and food preparation, improper refrigeration facilities, poor sanitation, and the presence of vectors such as flies that can transmit the germs can lead to the spread of the disease.³

The most common cause (in 90% of cases) of traveller’s diarrhoea is bacteria. Commonly responsible bacterial species include ²

• Enterotoxigenic Escherichia coli (30-60%)
• Campylobacter jejuni
• Shigella spp
• Salmonella spp
• Yersinia enterocolitica

Viral pathogens such as norovirus, rotavirus, and astrovirus are responsible for 10% of the cases.²

Parasites like Giardia lamblia, Entamoeba histolytica, Cyclospora, and Cryptosporidium parvum can cause the illness rarely, with a longer duration of symptoms.²

Risk factors for traveller’s diarrhoea

Certain host and environmental factors increase the risk of traveller’s diarrhoea.⁴

Host factors

• Young age - Children and young adults tend to develop the disease more than older adults
• Weakened immune system
• Other underlying medical conditions (i.e. inflammatory bowel disease, kidney and heart diseases)
• Genetic susceptibility
• Use of certain drugs like proton pump inhibitors
• Poor knowledge about proper hygiene practices

Environmental factors

• High risk destinations - in Central and South America, Mexico, Africa, South and Southeast Asia
• Warmer climate
• Lack of clean water
• Lack of sanitary facilities 

Clinical presentation

Symptoms of traveller’s diarrhoea can occur while you are on the trip or even after returning home.⁵ 

These are²

• Passage of 3 or more watery loose stools in a day
• Urgent need to pass stools
• Abdominal pain and cramps
• Fever
• Nausea
• Vomiting 
• Blood and mucus in stools (rare)

Many individuals only experience mild symptoms that do not affect planned activities. However, some can have severe incapacitating symptoms which might interfere with plans. In the large majority, symptoms go away on their own within 3 to 5 days, but if caused by a parasite, they might last for a few weeks or even months.⁴

Complications of traveller’s diarrhoea

Traveller’s diarrhoea is a self-limiting disease. However, it can cause complications during the illness and can last long term.⁶ 

• Dehydration and electrolyte imbalances
• Sepsis
• Hemolytic-uremic syndrome (a condition affecting blood vessels and kidneys)
• Postinfectious irritable bowel syndrome
• Guillain-Barre syndrome (a condition affecting nerves)
• Reactive arthritis (swelling and pain of joints)

Dangers of dehydration

When the fluid that is lost from the body due to diarrhoea and excessive vomiting is not replaced, it can cause low blood pressure and shock. Impaired blood supply to vital organs like the kidneys and liver can make them shut down. Sodium, potassium, urea and other electrolytes can rise to dangerous levels, and all these problems can result in coma and ultimately death.⁷ Therefore, adequate fluid replenishment is essential. 

What is oral rehydration solution (ORS)?

Although homemade fluids such as water, clear soups, diluted juices and sports drinks are adequate for hydration in very mild cases of traveller’s diarrhoea, for more severe symptoms, oral rehydration solution (ORS) is recommended.¹ ORS is available as packaged oral rehydration salt powder, which can be prepared using boiled, cooled water. They are widely available in pharmacies and stores in most countries. 

ORS contains a balanced mix of water, sodium and other salts, and glucose as follows:

• Sodium - 75 mmol/L
• Potassium - 20 mmol/L
• Chloride - 65 mmol/L
• Citrate - 10 mmol/L
• Glucose - 75 mmol/L⁸

This optimum balance of sodium and glucose helps the gut to absorb fluids and sodium more efficiently.⁸ Sodium and potassium in ORS replace the loss of these essential ions because of diarrhoea and vomiting. Citrate in the ORS corrects the acidosis resulting from dehydration.

Preparation and use of ORS

ORS is available prepackaged or is to be prepared by mixing with boiled, cooled or bottled water. It is available in different sizes, and according to package instructions, the powder should be dissolved in 200 ml, 500 ml, or 1 L of water. Additional salts or sugar should not be added during preparation.  Prepared solutions can be kept for 24 hours in the refrigerator or 8-12 hours at room temperature, but should be discarded afterwards if not used.  

Children above the age of 10 years and adults can have ORS as much as they want, approximately 2 L per day. Children between 2 and 9 years old should be given 100-200 ml of ORS after each loose stool. Children less than 2 years old should only be given 50- 100 ml after each diarrheal episode. Small sips of ORS can be taken if oral intake is difficult due to nausea or vomiting.

ORS should be used with caution in those with cirrhosis of the liver, renal failure and heart failure.  Infants should continue breastfeeding, and children and adults should continue to have solid food in addition to ORS.

Benefits and limitations of ORS for travellers’ diarrhoea

ORS carries multiple benefits in treating traveller’s diarrhoea. These are,

• Ability to quickly replenish lost fluids and re-establish electrolyte balance due to its unique composition. 
• One-size-fits-all treatment option, as it can be used in both children and adults.
• Low cost and wide availability provide easy access for tourists around the world.
• It can be prepared easily with only packed sachets and clean water.
• Ability to remain fresh for several hours at room temperature, which is important in resource-scarce settings. 

However, it carries some limitations as well:

• ORS can not cure the illness by itself and can only treat dehydration and help prevent complications.
• Individuals may need additional treatment, such as antibiotics, to act against the causative organisms.
• It is unsuitable for people with severe disease, as they would require intravenous fluids and other medicines.

Adjunct treatment options

In addition to ORS, a few other treatment options can be used in managing traveller’s diarrhoea.²

• Anti-diarrheal medication (i.e. loperamide)

These provide symptom relief by reducing bowel movements, shortening the duration and severity of diarrhoea. Not recommended when the diarrhoea is bloody or is accompanied by fever. Since it won’t treat the infection, germs will remain in the gut and can pass to others. Taking an excess of these medications can cause constipation.

• Antibiotics

Beneficial in moderate to severe diarrhoea to reduce the severity and duration of the diarrhoea. Antibiotics such as azithromycin, ciprofloxacin and rifaximin are used. These are not used in milder forms of disease.

• Probiotics (i.e. Lactobacilli, Bifidobacteria)

Used in both the treatment and prevention of diarrhoea. They have a beneficial effect on intestinal flora and suppress pathogenic bacteria. 

When should you see a doctor?

Most cases of traveller’s diarrhoea are mild and do not require any treatment. However, medical attention should be sought if the individual develops,

• Severe dehydration with extreme thirst, very dry mouth, little or no urine and dizziness
• Bloody diarrhea
• Intractable vomiting
• Severe abdominal pain
• High fever (>102⁰F or 39⁰C)
• Persisting symptoms for more than 48 hours  

Can traveller’s diarrhoea be prevented?

Even though exposure to germs cannot be prevented completely, the risk for traveller’s diarrhoea can be minimised by maintaining good hygiene practices such as:⁴

• Washing hands frequently with soap, especially after using the toilet and before eating and drinking -  use an alcohol based hand sanitiser if washing is not possible
• Adhering to proper food preparation techniques (cooking, boiling and peeling)
• Avoiding high-risk products like salads, raw and leafy vegetables, cold sauces and dressings, and raw meat and seafood⁵ (canned food, bread, and fruits that can be peeled are generally safer)
• Using boiled, filtered or bottled safe water, instead of tap water
• Avoiding contact with potentially contaminated waters during recreational activities

Certain drugs are also used to prevent travellers’ diarrhoea, but these are not used routinely, and are only given in specific circumstances because their side effects can be worse than the diarrhoea.²

• Antibiotics - These are given to high-risk individuals(low immunity, other medical problems) for short durations
• Bismuth Subsalicylate - It decreases the likelihood of diarrhoea. It should not be taken for more than 3 weeks and should be avoided during pregnancy and in those who have aspirin allergies
• Probiotics - studies have shown that probiotics are useful in preventing travellers’ diarrhea⁹

Currently, there aren’t any vaccines that can provide satisfactory protection against travellers’ diarrhoea.⁴ However, the only commercially available cholera vaccine can provide some protection against enterotoxigenic E. coli, one pathogen responsible for traveller's diarrhea¹⁰

Summary

• Traveller’s diarrhoea is a common illness of the gut experienced by tourists travelling to tropical and subtropical regions.
• Spread is via contaminated food, water and utensils, through the faeco-oral route
• It results in symptoms such as diarrhoea, vomiting, abdominal pain and fever
• The commonest complication is dehydration and electrolyte imbalance
• Oral Rehydration Solution (ORS) helps to replace lost fluids and electrolytes, which is crucial for preventing and managing dehydration
• It is available as packed sachets, which are easy to prepare with boiled water
• Anti-diarrheals, antibiotics and probiotics can be used as adjunct therapies
• It is a self-remitting illness, and most cases do not require any treatment
• Development of bloody diarrhoea, severe dehydration, intractable vomiting and high fever warrants medical attention.
• Adherence to good hygienic practices, use of prophylactic antibiotics and other medicines can help prevent acquiring traveller’s diarrhoea