Introduction

Traveller's diarrhoea is an infection of the digestive tract that affects travellers. The major symptoms of this disease include watery stool and abdominal cramps.

It is the most common travel-related illness, affecting about 50% of travelers. It occurs more in hot and humid areas, such as Asia, the Middle East, Africa, and Latin America, where bacteria breed more easily.  

Studies show that approximately 80% to 90% of traveler's diarrhoea cases are caused by bacteria, and 5% to 15% by intestinal viruses.¹ Most cases are mild, last a few days, and are resolved without any treatment. In severe cases, you might have to see a healthcare professional.

Among immunocompromised travelers, the risk of acquiring travel-related infections like travelers' diarrhoea may be high due to deficits in their immune system, which is a result of a reduced ability to mount an effective immune response and fight off infections.²

Symptoms

Here are the most common symptoms of travelers' diarrhoea:

• Watery stool passed frequently (three or more times a day)
• Urgency in the need to use the toilet
• Stomach cramps
• Intestinal rumbling 
• Nausea
• Vomiting
• Fever
• Moderate to severe dehydration

If these symptoms last longer than a few days, it is necessary to visit a doctor.

Causes 

Travelers' diarrhoea is usually caused by infectious agents such as bacteria, viruses, or parasites. Typically, when you consume food or water that is contaminated by these infectious agents, you will develop travelers' diarrhoea.

The microorganisms that cause travelers' diarrhoea include

• Bacteria: Escherichia coli (ETEC and EAEC), this is one of the most common bacterial causes of travelers' diarrhoea. Other bacteria that may cause travelers' diarrhoea include Campylobacter jejuni, Salmonella species, and Shigella species.
• Parasites: Giardia intestinalis, Entamoeba histolytica, Cryptosporidium parvum
• Viruses: norovirus and rotavirus

There are also cases where no causes are found.

Why are immunocompromised individuals at a higher risk?

An immunocompromised person is one whose immune system is not functioning as it should. This means that your body will be unable to fight off infections as it should, and you could get sick more often and with more severity than someone with a normally functioning immune system.

You can be born with a condition that compromises your immune system (eg, autoimmune diseases), or infections, medications, cancer, organ transplant, or other health conditions you acquire throughout your life can weaken it.³

A weakened immune system makes it harder to fight infections, so instead of going away on its own after a few days, travelers' diarrhoea may persist.

Traveler's diarrhoea is one of the most common infections seen amongst immunocompromised travelers.⁴

Symptoms in immunocompromised individuals

• Mild to severe diarrhoea, which may also be bloody or contain mucus
• High fever and systemic illness
• Symptoms may last for more than 14 days
• Severe dehydration, resulting in an increased risk of hypovolemic shock
• Failure to respond to standard treatments 
• Weight loss and malnutrition

Complications in immunocompromised individuals 

If you have a compromised immune system, you are at a higher risk of developing complications due to your immune system's inability to mount an effective immune response and fight off infections, bacterial translocation (when bacteria move from the gut to other parts of the body and cause infections), and, generally, you are also more susceptible to infections. Let us look at some complications that you may experience:

• Dehydration and electrolyte imbalance, which can lead to kidney failure and metabolic acidosis
• Bacteremia and sepsis
• Chronic diarrhoea and malabsorption 
• Infections that spread to other parts of the body (opportunistic infections)⁵
• Organ damage, such as kidney or liver problems
• Respiratory failure can be life-threatening

Diagnosis 

Stool tests

• Bacterial culture
• PCR testing
• Stool ova and parasite exam
• C.difficile toxin test (for suspected antibiotic-associated diarrhoea)

Blood tests

• Complete blood count (CBC)
• Blood cultures
• CMV PCR – For suspected CMV colitis in transplant patients or HIV/AIDS

Endoscopy (if needed)

Colonoscopy with biopsy is used to diagnose CMV colitis,⁶ amoebiasis, or chronic diarrhoea of unknown cause.

Prevention strategies for immunocompromised travelers 

• Avoid untreated water
• Eat only well-cooked food (avoid raw salads and street foods)
• Wash your hands frequently and use an alcohol based sanitiser afterwards
• If you are considered a “high-risk” traveller (eg, a transplant patient), your doctor should prescribe prophylactic antibiotics
• Vaccines like the oral cholera vaccine may protect against some bacteria

Treating travelers diarrhoea 

If you get travellers' diarrhoea, it is very important to stay hydrated and replace lost electrolytes. Here are some ways travellers' diarrhoea can be treated:

• Fluid replacement: You have lost too much fluid and electrolytes due to frequent stooling; therefore, you need to drink plenty of fluids like water, broths, or electrolyte-rich beverages to replenish your body and prevent dehydration.
• Rest: Your body is going through a lot of stress, so you need to rest as much as possible to allow your body to recover.
• Antibiotics: If your doctor prescribes antibiotics, take them as directed.
• Antidiarrhoeal medications: In some cases, your doctor may recommend medications to control the diarrhoea.

Summary 

Travellers' diarrhoea can be a serious condition, especially for immunocompromised individuals. If you're part of this group, you are more likely to experience severe, prolonged, and complicated symptoms.

Bacteria are the most common cause, but parasites and viruses can also be responsible. For accurate diagnoses, your doctor may perform stool tests, blood tests, and, in some cases, a colonoscopy.

Treatment options are antibiotics, antidiarrhoeal medications, and fluid replacement to prevent dehydration. Your doctor will decide what is best for your case.

To reduce the risk of travellers' diarrhoea, it is important to ensure that the water you drink during the course of your travel is safe and that the food you eat is prepared in a hygienic environment. If possible, avoid street food. Also, consider taking preventive antibiotics if necessary.

If you experience travelers' diarrhoea, seek medical attention promptly to prevent complications.