Overview

Traveler’s diarrhoea arises from ingesting tainted food or water while travelling abroad. Unsanitary cooking conditions or inadequate hygiene in the areas where tourists visit to eat might be the source. Frequently, those affected by traveler’s diarrhoea typically experience symptoms such as cramping in the stomach, dehydration, fever, nausea, vomiting, and watery diarrhoea over 3-5 days. Three or more loose stools in 24 hours or a two-fold increase from normal bowel habits are considered signs of travellers' diarrhoea.¹ There are different causes of traveler’s diarrhoea but bacteria is usually the main cause of the symptoms, particularly Escherichia coli (E.coli).² However, sometimes parasites and viruses may be responsible for symptoms experienced. It can be prevented by abstaining from raw foods, using bottled water, and being cautious while eating street food. 

Although it usually goes away on its own, more severe cases could require medical care and may cause long-term health effects that would engender Post-Infectious Irritable Bowel Syndrome (PI-IBS) and tropical sprue (acquired malnutrition), which have a range of secondary, co-related conditions. 

What is traveler’s diarrhoea

Traveler's diarrhoea is one of the most prevalent health problems that face people who travel abroad, especially to areas with inadequate sanitation and a lack of access to clean water. It is the most common condition linked to travel that impacts between 40 and 60% of travellers.¹ It usually results in gastrointestinal system distress and is brought on by consuming tainted food or water. The primary sign of traveller’s diarrhoea is three or more loose stools in 24 hours or a two-fold increase from normal bowel habits.¹

Although the majority of cases go away in a few days, there is evidence that suggests traveler's diarrhoea can cause long-term health problems. It is critical for both tourists and medical professionals to comprehend these long-term impacts. 

Causes and risk factors

Infectious microorganisms such as bacteria, viruses, and parasites are the main causes of traveler's diarrhoea. The infectious organism responsible for its symptoms differs by geographic area. It’s common that bacterial infections are the main reason, especially for tourists who travel to South and Southeast Asia.²

The most common bacterial causes which are usually associated with traveler’s diarrhoea:^2,3

• Escherichia coli (E.coli) - most common bacterial cause
• Campylobacter Jejuni
• Salmonella
• Shigella

The most common viral causes which are usually associated with traveler’s diarrhoea:²

• Norovirus (associated with cruise ship outbreaks)- the most common viral cause
• Rotavirus
• Astrovirus
• Sapovirus
• Adenovirus 40/41

Research shows there are over 40 million cases of traveler’s diarrhoea a year, due to international travel to high-risk regions. Especially when travelers visit areas with hot or humid climates. This increases the risk factor of developing traveler's diarrhoea, as it gives better conditions that ensures bacterial growth.^4,5

A high proportion of travelers who contracted the condition visited the following continents:^4,5

• Africa
• Central America
• South America
• South and Southeast Asia

Short-term symptoms 

Symptoms of traveler’s diarrhoea typically appear within one to two days of exposure. These may include:¹

• Watery or loose stools
• Two-fold increase in normal bowel movements
• Abdominal (stomach) cramps
• Nausea and vomiting
• Fevers

Management and treatment 

First and foremost, travelers should be aware of the prospect of the traveler's diarrhoea before departing to high-risk countries. Taking proactive measures like avoiding tap water and ice, green vegetables, unpeeled fruit, street food vendors, and frequently washing hands. 

As traveler’s diarrhoea usually goes away on its own, it is recommended to prioritise rehydration due to water loss because of diarrhoea. Over-the-counter rehydration formulas can rehydrate those with symptoms and prevent fluid loss. Additionally, anti-diarrhoea medication can be purchased over-the-counter to help limit episodes. In severe or persistent cases, healthcare professionals may prescribe antibiotics if stool samples confirm bacterial infection.⁶

Long-term effects of traveler’s diarrhoea

Post-Infectious Irritable Bowel Syndrome (PI-IBS)

After having traveler’s diarrhoea, some people develop Post-infectious irritable bowel syndrome (PI-IBS). It is one of the most noted long-term effects associated with traveler’s diarrhoea. Research shows, 5–15% of patients experience PI-IBS, having symptoms of:⁷

• Persistent stomach discomfort
• Bloating
• Persistent changes in bowel habits (constipation, diarrhoea, or both)

It is not clear as to why some people get PI-IBS after having traveler's diarrhoea. Experts think it might be due to mild ongoing inflammation in the gut. Additionally, some experts believe it might be due to travelers frequently using heartburn medications to reduce stomach acid (which usually helps protect against infections). Another explanation refers to bacterial infection acquired from contaminated food that disrupts the balance of good gut bacteria that lives in your intestines and leads to a lower count which could result in bowel habit changes. Finally, symptoms of PI-IBS could also occur from problems with your immune system defence mechanisms.⁷

Notably, after the first time experiencing traveler's diarrhoea, some people's digestive systems become extra sensitive, and the peristalsis gets disrupted. Nerve and movement mechanisms can change after the infection, causing the gut to become extra sensitive, consequently, this increases the risk of developing PI-IBS. 

Research suggests you are also more likely to develop these long-term problems:^7,8

• If you are a woman over 40
• Had a really bad or long-lasting infection ( longer than 3-5 days)
•  Stress or anxiety during the infection

Women around middle-age might be more vulnerable because of hormone changes and differences in how their immune system responds to infections.⁸

Tropical sprue (acquired malnutrition condition) 

Long-term traveler’s diarrhoea can also be linked to tropical sprue. It commonly affects people who stay in tropical places for a long time, as the name suggests. Tropical sprue describes the situation where reduced absorption of vitamins from the start and end parts of the small intestine, mainly due to the gut’s deterioration.^9,10 The gut wall, or mucosa, is fundamental in absorbing nutrients. When traveler's diarrhoea causes swelling or hurts the gut’s thin barrier, that can mess up its physiological function. This long-term harm leads to chronic malabsorption issues.

Chronic gastrointestinal disturbances following infection can impair nutrient absorption, promoting deficiencies in:^9,12

• Vitamin B12
• Iron
• Fat-soluble vitamins (A, D, E, K)

These deficiencies can induce fatigue, anaemia, and other long-term health complications.^11,12

Importantly, vitamin B12 absorption is particularly vulnerable because it requires a specialised process involving intrinsic factors produced in the stomach and specific receptors in the terminal end of the small intestine. After the infection, swelling in the gut can interfere with these mechanisms, causing vitamin B12 deficiency. This may show as neurological symptoms like numbness and tingling in the hands and feet, cognitive changes, and balance problems.

Iron absorption, which primarily occurs in the small intestine, depends on an acidic environment and healthy intestinal cells. When these areas are damaged by the infection, iron uptake decreases, potentially resulting in iron-deficiency anaemia. This may manifest as signs and symptoms such as dizziness, fatigue, lack of energy, irritability, pale skin, and weakness.¹³

The absorption of fat-soluble vitamins (A, D, E, and K) requires proper fat digestion and bile salt function.¹⁴ Post-infectious changes can disrupt these processes by:

• Damaging cells that produce digestive enzymes
• Altering bile salt recycling
• Creating an environment where fats pass through the digestive tract unabsorbed

If tropical sprue is left unmanaged, vitamin deficiency may lead to an array of different symptoms. For example, vitamin A deficiency may lead to night blindness due to the role of vitamin A in maintaining vision health.¹⁵ Moreover, insufficient vitamin D affects bone health and is tied to higher risk of infections as well as autoimmune conditions. Lastly, vitamin E deficiency has been associated with muscular weakness and neurological problems, whilst vitamin K deficiency results in symptoms such as unexplained bleeding and bruising, bone pain or lack of bone development.^16,17

These nutritional impacts can create a vicious cycle where poor nutrient status further impairs intestinal healing, prolonging the post-infectious state. For people with chronic symptoms after infection, seeing a healthcare professional and nutritionist may be needed to start nutritional recovery through supplements and meal planning.

Summary

To conclude, traveler’s diarrhoea is a common health problem that affects people who travel abroad. This can be due to when travelers eat food or water contaminated with microorganisms like bacteria, resulting in gastrointestinal distress, mainly frequent diarrhoea. This is especially prevalent when tourists travel to areas with inadequate sanitation in the food preparation area and have limited access to clean water. It is linked especially to travel in tropical and hot climates such as Africa and Asia. Research suggests that it impacts between 40-60% of travellers and is more likely to affect women. It often leads to runny and frequent stools, stomach pain, and feeling sick. It usually goes away by itself, but it can cause long-term problems like post-infectious irritable bowel syndrome (PI-IBS). This is when peristalsis and feeling are still altered following infection for a long time. In addition, tropical sprue, a long-term malabsorption issue that stops the body from taking in nutrients well, is also associated with traveler’s diarrhoea. This leads to low levels of vitamins like B12, iron, and other fat-soluble vitamins. Consequently, in post-infection, vitamin deficiency can result in secondary conditions like iron deficiency anaemia or night blindness. Seeing a healthcare professional and nutritionist may help to manage gastrointestinal symptoms and restore vitamin levels.