Travelling to new and international destinations is exciting for most of us, particularly if this is your holiday of a lifetime. However, it can be quite stressful if you are one of the unfortunate people who develops “Travellers’ Diarrhoea” (TD).
By being well prepared for your travels, reducing the amount of stress, and taking some sensible precautions to reduce your chances of getting ill whilst travelling, you are assured of enjoying that special getaway to paradise. Although TD is rarely life-threatening, it can be a significant nuisance and place a substantial economic burden on those individuals that are unlucky enough to contract it.
What is Traveller's Diarrhoea (TD)?
Millions of people are affected by Traveller’s Diarrhoea (TD) each year, a painful and debilitating illness whose impacts extend far beyond disrupted travel plans. Traveller’s Diarrhoea has a significant impact on local economies, tourism and businesses all over the world. Read on to see the scale of the impact in your sector, likely causes and the best methods for prevention.
TD is characterised by the passage of three or more unformed stools in a 24-hour period associated with at least one of the following symptoms:
- Abdominal cramps
What is the Economic Impact of TD?
TD exerts a significant economic impact on affected individuals, the country of origin of the traveller, as well as the countries with risks of TD.These include healthcare costs, loss of revenue, loss of business opportunities, and loss of productivity.
Apart from time taken off work due to TD, the cost of a ruined holiday to a high risk destination is at least GBP £2,966 per person (Based on US Data - July 2018).
The costs associated with TD can occur during any of the three phases of the travel process:
- Cost of pre-travel health advice
- Cost of self-treating medication
2. During Travel
- Revenue loss for tourism countries due to illness
- Cost of medical care, lost business opportunities, etc
- Healthcare costs for ill-returned travellers
- Lost productivity costs due to work absenteeism
Acquiring TD may cause 12-46% of travellers to change their travel plans.
What is the Impact of TD on the traveller's health?
Although TD is rarely life-threatening, it can be a significant nuisance for the traveller. At least 1% of TD patients are hospitalized while 20% are confined to bed for 1-2 days.
Symptoms appear during the first two weeks of travel and usually last about 3-5 days, even if untreated. However, 5–10% of the cases may last for more than 2 weeks (persistent TD) and another 1–3% of the cases may last more than a month resulting in chronic diarrhoea. Severe diarrhoea can cause loss of water and salt, resulting in renal impairment and electrolyte disturbances. This may also restrict the absorption of medication.
TD can also be associated with potentially disabling enteric and extra-intestinal long-term complications. In 3-17% of TD patients, the intestines may become sensitised following a TD infection, resulting in post-infectious chronic symptoms of irritable bowel syndrome (PI-IBS).
Other post-infectious complications include reactive arthritis, Guillain-Barré Syndrome (GBS is the onset of muscle weakness as a result of damage to the peripheral nervous system), and the onset of idiopathic inflammatory bowel disease – both Crohn’s disease and ulcerative colitis.
What is the Economic Impact of TD on Health Services and Insurance Companies?
TD may result in medical costs being incurred in both local and home country healthcare facilities, with far-ranging implications for both individuals and insurance or managed healthcare companies.
The average cost of one episode of TD is estimated to be £1,110 and £1,517 for leisure and business travellers, respectively.
With over 50 million traveling from industrialised to developing countries each year and an estimated 24-40 million individuals being affected by TD, the cost to business is clearly significant.
Further research is required to validate actual total global figures related to the cost of TD, but the above does emphasise the considerable economic burden of TD.
What is the Economic Impact of TD on the Tourism Industry?
Although TD is usually a self-limiting disease, it is sometimes seen as a perceived threat and can also cause incapacitation, thereby interfering with or disrupting travel itineraries. This has serious potential financial implications for the travel industry:
- Customers actively avoiding 'high risk' destinations
- Travel industry staff themselves becoming incapacitated due to TD
- Travel industry staff dealing with customers in medical difficulty
- Customers blaming providers for TD resulting in compensation claims
Although the total cost to the global travel industry has never been quantified, the loss is considered to be enormous. For example, the consequent cost in terms of lost revenue to the UK travel industry (outbound) is estimated at £2 billion per annum.
What is the Economic Impact of TD on Countries with intermediate to high risk of TD?
Countries with an intermediate to high risk of TD also suffer significant revenue losses. It has been estimated that one incapacitation day of travellers with with TD results in a revenue loss to the global tourism industry of £220 to £370 million of lost revenue.
Apart from avoiding countries with high risk of TD, 60% of UK holidaymakers who experience TD would never visit that country again. The consequent economic impact, from UK tourist alone, to countries with an intermediate to high risk of TD, is estimated at £6 billion £4.2 billion from avoiding these countries; £1.8 billion from loss of expenditure caused by incapacitated holidaymakers) per annum.
How can TD be alleviated?
Prevention of TD falls into four broad categories: avoidance, immunisation, non-antibiotic therapy, and antibiotic prophylaxis.
1. Counselling high-risk patients and those traveling to high risk areas, helping them make choices and plan their travel appropriately in order to mitigate the risks of infection.
2. Educating travellers about safe choices of food and beverages, and appropriate sanitary precautions. However, this is often not practical with travellers ignoring advice owing to their care-free nature, adventurous spirit and the eagerness to experience new cultures. More than 95% of travellers ignore the advice of ‘safe’ eating and drinking within a few days of leaving home.
"Boil it, cook it, peel it, or forget it" ...easy to remember but impossible to do!
There is little role for vaccines in the prevention of TD as there are no vaccines available for most of the pathogens that cause TD. The oral cholera vaccine may produce cross-protective immunity against some enterotoxigenic strains of E. coli. However, prevention is limited to 1-7% of cases which therefore does not make it practical as prophylaxis in TD.
Travellers to risky areas should however receive appropriate vaccination against other intestinal disorders such as Hepatitus A, cholera and typhoid.
Prophylactic use of antibiotics, although effective, is generally not recommended except for a very limited number of high risk individuals. This is due to the threat of global antibiotic resistance and adverse side effects.
It may also lead to a false sense of security resulting in less attention to eating in sanitary habits.
Bismuth subsalicylate (BSS), the active ingredient in Pepto-Bismol, is the most effective non-antibiotic agent for TD prophylaxis. However, due to the number of tablets required and the inconvenient dosing regimen, BSS is not commonly used as prophylaxis for TD.
Taking prebiotics to increase the fiendly bacteria in the gut seven days before travel and then daily for the duration of the holiday or business trip has been shown to reduce the incidence and severity of TD.
What are the sources of TD?
The mostly likely means of getting TD is through food and beverages contaminated with faecal matter. This is often the result of poor hygiene practices, lack of education, lack of public health infrastructure and lack of facilities for safe food preparation and storage.
Food contribute towards TD more than water and all raw food is subject to contamination. Raw or undercooked meat, fish, and shellfish can carry intestinal pathogens, and should be cooked and eaten hot. In areas where hygiene and sanitation is inadequate, travellers should avoid eating raw fruits, vegetables and salads that cannot either be washed in uncontaminated water, or be peeled by the travellers themselves.
What causes TD?
TD results from a variety of intestinal pathogens with bacteria being the most common, accounting for 80%–90% of cases.
Enterotoxigenic Escherichia coli (ETEC) is responsible for the majority of infections globally, whereas Campylobacter jejuni is associated with most cases in Southeast Asia, particularly in Thailand. Shigella, Salmonella and Aeromonas species, as well as noncholera vibrios are also known to cause TD.
Intestinal viruses such as norovirus, rotavirus, and astrovirus are responsible for 5%–8% of the cases. Infections with parasites such as Entamoeba histolytica and Giardia intestinalis account for approximately 10% of diagnoses in longer-term travellers and are slower to manifest and more commonly chronic in nature.
Water should be considered safe only if it is properly boiled or carbonated.
Local tap water, ice cubes, and unpasteurised milk should be considered contaminated and travellers are particularly advised to check if the seal is intact on all bottled water.
Recreational activities such as swimming, wading, or participating in other activities involving water in inadequately treated pools, interactive fountains (splash pads or spray parks), hot tubs and spas, as well as rivers and oceans contaminated with sewage, may also cause a significant threat.
What are the risk factors for TD?
Travel destination is considered the most important determinant of risk and the world can be divided into three regions based on the risk grade of TD:
- Low risk:
<7% attack rate
Including the United States, Canada, Australia, New Zealand, Japan, and countries in Northern and Western Europe.
- Intermediate risk:
8-20% attack rate
Including those in Eastern and Southern Europe, South Africa, Israel and some of the Caribbean islands.
- High Risk:
20-75% attack rate
Including most of Asia, the Middle East, Africa, Mexico, as well as Central and South America.
In more temperate regions, there may be seasonal variations in the risk of diarrhoea and attack rates of TD have been found to be highest during summer and the rainy/monsoon seasons.
In the developing regions of the world where public health facilities such as plumbing or latrines are not accessible, the amount of faecal contamination is significantly higher. The lack of adequate food preparation and storage facilities such as proper refrigeration also contributes to the high rate of TD attacks in those regions.
Moreover, the lack of safe water may result in contaminated food and beverages while shortage of water supply leads to inadequately cleaned hands, utensils and foods such as fruit and vegetables. Consumption of food and beverages obtained from street vendors is also particularly risky.
The type of traveller also influences the likelihood of developing TD. Among these, students and low-budget tourists are the most susceptible. Business travellers are at intermediate risk whilst those who are visiting friends and relatives are the least affected. High risk individuals include patients with insulin independent diabetes, congestive heart failure, advanced cancer, HIV infection and those with inflammatory bowel disease or other bowel abnormalities.
Although gender has no influence on the incidence of TD, age does play a role and those with the highest incidence include small children and adults aged 21 to 29 years.
Causes of TD by country
ETEC (Enterotoxigenic E. coli) and Enteroaggregative E.coli (EAEC) are the main contributors for TD cases occurring in Latin America, Africa, South Asia and Middle East.
Percentage incidence of travellers’ diarrhoea caused by enterotoxigenic Eschericia coli.
- Low risk: <8%
- Intermediate risk: 8-20%
- High risk: 20-90%
Campylobacter jejuni is more common in Southeast Asia, particularly in Thailand. Campylobacter infections are also common in Nepal.
In South and Southeast Asia, Shigella and Salmonella are also important contributors for traveller’s diarrhoea cases. Vibrio parahaemolyticus has been isolated particularly in travellers to Southeast Asia. Vibrio cholerae is a rare causative agent, limited mostly to aid workers visiting areas affected by cholera epidemics.
Among parasites, Giardia intestinalis is an important cause of diarrhoea in travellers to the mountainous regions of North America and to St. Petersburg, Russia, but has also been isolated from other parts of the globe. The most well-known risk areas for Cyclospora infections are in Nepal, Peru, Haiti, and Guatemala.
What should you do if you get TD?
Depending on the country of travel and the preparation by individuals, adequate medical treatment may not be easily accessible for the following reasons:
- Unfamiliarity with local healthcare systems
- Time restrictions
- Language barriers
- Poor or no medical facilities available
It is therefore important that travellers are briefed with regards to the knowledge and treatment of TD and provided with suitable medication where justified.
The prevention and treatment of dehydration is of particular concern in young children, pregnant women, the elderly and compromised patients.
Commercially available oral rehydration salts (ORS) are readily available and should be purchased prior to travel if necessary.
These remain a principal element in the treatment of TD. They provide quick relief of symptoms if the pathogen is susceptible to the particular antibiotic that is given.
These provide symptomatic relief and are suitable for adjunctive therapy with antibiotics. They are also suitable for use in mild cases of TD in conjunction with oral rehydration salts, but if the condition worsens over a 24-hour period then seek medical advice.
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