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Prevention and management of food poisoning

Food poisoning can occur equally at home or overseas. There are limited vaccination options so travel consultations are a good opportunity to discuss food safety and water hygiene to reduce the risks of this occurring. This article outlines the food and water-borne diseases that travellers could contract, why some travellers may be at higher risk, how to reduce risk through food choices and how to deal with travellers' diarrhoea.

Food poisoning

Food poisoning is the overall description of the symptoms caused by eating contaminated food, which may include nausea, vomiting, diarrhoea and stomach cramps. Despite strict food safety and hygiene regulations, 84,560 confirmed cases of food poisoning were reported in England and Wales in 2010, with the main cause being campylobacter.1,2 Since symptoms do not usually last more than a couple of days, it is extremely likely that there would have been many more unreported cases.

Travellers are often more vulnerable to food and water-borne diseases because they depend on the food hygiene standards of hotels and restaurants when seeking out new cultural experiences and wanting to try local cuisines. Additionally, in countries with warmer climates, there are often more pathogens in the environment.

Food and water-borne diseases

There are many diseases that can be contracted through contaminated food and water:

 - Tapeworms: these can be ingested through undercooked meat, with pork being especially dangerous as infection can cause cysts to develop in the brain.

 - Hepatitis A and E viruses: these can cause fever, malaise, nausea and jaundice.

 - Marine poisoning: this is caused by ingesting fish that have eaten concentrated toxins from algae or bacteria, eg. scromboid, ciguatera or puffer fish poisoning.

Poliovirus: this can range from mild symptoms to meningitis or paralysis (rare in travellers).

 - Typhoid/paratyphoid (enteric fever): typhoid can cause fever, headache, malaise, anorexia, abdominal pain, intestinal perforation, and bacteraemia. It is possible to become a chronic carrier of typhoid with the ability to pass on the virus to other people for a year without having symptoms. Paratyphoid is similar but less severe and shorter duration.

 - Dysentery: this causes cramping, abdominal pain, tenderness, low-grade fever, bloody stools with mucus, and weight loss.3

Travellers' diarrhoea

Travellers' diarrhoea (TD) is thought to be the most common health issue experienced by travellers, affecting between 20-60% of those going to higher risk areas of the world, such as Africa, Latin America, the Middle East and most parts of Asia. Particularly high-risk countries include Egypt, India, Thailand, Pakistan, Morocco and Kenya. TD is commonly defined as three or more loose stools passed in a 24-hour period, cramping, nausea and low-grade fever. Vomiting and bloody stools are less common.3,4 

Examples of pathogens that could be present in food and cause travellers diarrhoea include:

Bacteria (30-60% cases)

 - Enterotoxigenic Escherichia coli.

 - Enteroaggregative Escherichia coli.

 - Salmonella.

 - Shigella.

 - Campylobacter.

 - Cholera.

Enteric viruses (5-20% cases)

 - Norovirus.

 - Rotavirus.

Protozoan parasites (

 - Giardia.

 - Cryptosporidium.

 - Entamoeba histolytica.

Acute food poisoning from toxins (

 - Staphylococcus aureus.

 - Bacillus cereus.

 - Clostridium perfringens.3

Vaccinations available 

Vaccinations are only available against hepatitis A, typhoid, polio and cholera. Since these diseases are able to cause local outbreaks if brought back by a traveller, the vaccinations are made available free on the NHS.5 Rotavirus vaccine is now also available and is being introduced into the childhood vaccination program in the UK.6

Since there is no vaccine against TD or many of the diseases that cause food poisoning, it is vital to give travellers advice during their pre-travel consultation to make them aware of the issues and hopefully avoid issues, or at least know how to manage them.

Higher-risk travellers

Risk assessment during the pre-travel consultation is vital to assess the traveller's risk of contracting diseases and tailor appropriate advice to their specific trip and type of travel.5

Backpackers: these travellers travel for longer periods so can venture away from usual tourist areas, where food hygiene and quality standards may be lower. They also may have less money to spend and so opt for cheaper restaurants where standards may be even lower. A recent survey of 404 backpackers in Thailand found that 30.7% experienced TD during their trip. Ice in drinks was one of the highest risk factors.7

Young children: young children are more prone to diarrhoea because they have less awareness of dangers and tend to put everything in their mouths. The effects of diarrhoea can be more severe or even life-threatening due to rapid dehydration.8

Visiting friends and family (VFR): this may involve travelling to a more rural or resource-poor location, having to rely on family members to cook, and no longer being used to local cuisine, increasing their vulnerability to infection.3

Missionaries and humanitarian aid workers: these work in extreme conditions, such as remote locations, slums, refugee camps, and frontline medical facilities. They may have limited access to cooking facilities and have to rely on the limited foods available locally. They may also be expected to partake in local food customs so as not to offend the people they are working with.9

Elderly, immunocompromised or people with underlying medical problems may be more susceptible to complications following diarrhoea and dehydration and may need to seek medical attention early. 3

Travel health advice

Travellers need to be aware of the risks present in contaminated food and water abroad so this should always be discussed during travel consultations. Written information or websites could be given to travellers to read later as consultation times are often limited.5

What to avoid:

 - Water - unboiled, unfiltered or unsterilised.

 - Ice in drinks (often made with tap water and freezing does not kill germs).

 - Ice cream.

 - Cream.

 - Cheese.

 - Unboiled or unpasteurised milk.

 - Raw vegetables or salad, eg. lettuce.

 - Unpeeled fruits, eg. strawberries.

 - Undercooked eggs.

 - Cooked food which has been allowed to go cold (eg. quiche and cold pizza), especially if uncovered and prone to contamination from flies.

 - Hotel buffet food that has been sitting out for a long time.

 - Cooked food that has been inadequately re-heated.

 - Dishes containing meat (often more hazardous than vegetarian options).

 - Left over rice, including fried rice (unless very well cooked).

 - Drinks like yoghurt, ice and fruit mixtures (eg. Indian lassi, cocktails) with ingredients which are likely to have been handled during preparation.

 - Cold sauces and toppings (may be diluted with tap water).8,10

Traditionally travellers have been taught the saying “peel it, boil it, cook it or forget it” to help to remember the rules to keep them safe. This is often only useful if the travellers are preparing their own food, however this is difficult to apply when eating out. Shlim (2005) suggests that eating out may be hazardous if cooks are unaware of the importance of hand washing, especially after using the toilet, resulting in the prepared food being contaminated. Sinks and hot water may not be available, the same chopping boards may be used for raw meat and vegetables and refrigerators may not always be available or have reliable, continuous electricity supply.11

Travellers therefore need to be advised to choose restaurants wisely. Street food that is well cooked (usually boiled or fried) in front of the traveller and served steaming on clean disposable plates is 

usually safe. It is advisable to choose busy restaurants and cafes with a good reputation and a high turnover of food, and avoiding food on buffets that has been standing at room temperature for a long period.8

Personal hygiene is also vital to prevent the spread of diseases, involving regular hand washing, especially after using the toilet or changing children's nappies, after touching animals and before eating. Also keep finger nails short - especially in children who put their fingers in their mouths regularly.8,10 Fecal contamination of swimming pools has also been associated with outbreaks of gastrointestinal illness4 so care should be taken not to drink pool water while swimming. Travellers should also ensure they have comprehensive travel insurance.

Management of travellers diarrhoea 

Since 20-60% of travellers to low-income countries experience diarrhoea, all need to be prepared and know how to manage it. 

Preventing dehydration is very important, especially when suffering from diarrhoea in hotter climates where fluid and electrolytes are also being lost through sweat. Adults should aim to slowly drink two cups of fluid (for example safe water, flat soft drinks, tea) after every bout of diarrhoea. Oral rehydration solution (ORS) should be used for children, elderly or anyone more prone to complications following dehydration.10

Preparations like loperamide are often used to treat diarrhoea in the UK, but travellers should be warned that this tends to constipate rather than cure the cause so must not be used if 

there is blood in the stool or if there is a fever greater than 38.5°C. However it can be a useful standby, if used with caution, to reduce frequent bouts of TD on long journeys or during important meetings.10

Antibiotics can help to reduce the severity and duration of moderate to severe TD. Ciprofloxacin is most commonly used but azithromycin may be more suitable in South and South East Asia because of resistance issues.12 Rifaximin is now also available as an alternative.13 These can be purchased from private travel clinics before travel if reliable medical facilities may not be available locally during the trip. If the TD continues for longer than three days, reliable medical advice should be sought as the cause may not be bacterial.

Some people find prebiotics and/or probiotics useful in the prevention or management of TD, as they help promote the beneficial bacteria in the gut. However a recent study found they had little effect on preventing or decreasing the duration of TD in travellers.14

When to see a doctor

Travellers should be encouraged to seek medical advice if they pass more that five loose stools in 24 hours, if it has blood in it, if they have a fever, if they continue to vomit, if they become dehydrated or are feeling very unwell. Travellers are also encouraged to see a doctor if diarrhoea continues for over a week.10 It is important to note that if travellers present for medical help post-travel, GPs must take this seriously and document a detailed travel history, as this is important for patient and public health management.15 An algorithm for diagnosing diarrhoeal illness post-travel can be found in the Resources section.  

 

Resources

National Travel Health Network and Centre

TRAVAX (subscription service)

Fit For Travel

Nomad Travel

InterHealth

Post-travel diarrhea algorithm

 

References

1. Food Standards Agency. Food Poisoning information

2. NHS Choices. Food Poisoning. 2011. 

3. Field VF, Ford L, Hill DR, Eds. Health Information for Overseas Travel. London: National Travel Health Network and Centre; 2010.

4. Lawrence J, Jones J. Foreign travel-associated illness: a focus on travellers' diarrhoea 2010 report. Version 2. London: Health Protection Agency; 2011. 

5. Chiodini J, Boyne L, Stillwell A, Grieve S. Travel health nursing: career and competence development. RCN guidance. RCN: London, 2012. 

6. Government Information Website (UK). Rotavirus Vaccine information.

7. Piyaphanee W, Kusolsuk T, Kittitrakul C, et al. Incidence and Impact of Travellers' Diarrhea Among Foreign Backpackers in Southeast Asia: A Result From Khao San Road, Bangkok. J Travel Med 2011;18(2):109-114.

8. Wilson-Howarth J, Ellis M. Your Child Abroad: A Travel Health Guide Second edition. Chalfont St Peter: Bradt Travel Guides Ltd; 2005.

9. InterHealth: Diarrhoea Information including section on “surviving hospitality”

10. Lankester T. Travel Health: Pocket Guide. Singapore: Berlitz; 2007

11. Schim D. Looking for Evidence that Personal Hygiene Precautions Prevent Traveler's Diarrhea. CID 2005:41(Suppl 8):s531-s535.

12. NaTHNaC. Travellers Diarrhoea Information Sheet. 2011. 

13. Electronic Medicines Compendium. Drug information and advice leaflets

14. Virk A, Mandrekar J, Berbari EF et al. A Randomized, Double Blind, Placebo Controlled Trial of an Oral Synbiotic (AKSB) for Prevention of Travelers' Diarrhea. J Travel Med 2013:20(2):88-94.

15. Price VA, Smith RAS, Douthwaite S, et al. General Physicians Do Not Take Adequate Travel Histories. J Travel Med 2011;18(4):271-274.