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COMMENTARY
Year : 2017  |  Volume : 5  |  Issue : 1  |  Page : 42-44

Travel health - Travel medicine


Department of Epidemiology, Biostatistics and Prevention Institute, University of Zurich, WHO Collaborating Centre of Travellers' Health, Zurich, Switzerland

Date of Web Publication20-Jan-2017

Correspondence Address:
Robert Steffen
Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Hirschengraben 84/E29, CH-8001 Zurich
Switzerland
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DOI: 10.4103/2468-6360.198796

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  Abstract 

In the post-World War II period, modern travel medicine was created as an interdisciplinary field not limited to tropical medicine and infectious diseases, but including also dive and high-altitude physiology, geriatrics, public health, etc. The goal is to keep future travellers alive and healthy, and to provide returning travellers with illness or sequelae of accidents the best possible care. With respect to both mortality and morbidity, we now have a broad idea about what is frequent, what in contrast is rare. However, particularly, the World Health Organization requests that more quality data should be generated to assure a safe evidence base for preventive recommendations. The lack of consensus on a global scale is the illustration that even 'experts' so far do not agree on all measures, be they advise immunisation or medication. A further challenge is that we are living in a constantly changing world. Hygienic conditions have improved in some locations, particularly such frequently visited by tourists and businessmen and women; also some infections are being eliminated or reduced by international efforts. On the other hand, new threats are emerging - infectious and other. Thus, in the coming decades, we must create an improved database. We must continue to be vigilant based on coordinated surveillance and we must continue to spread the news to both the travelling public and those health professionals advising them pre-departure, also those in charge of diagnosis and treatment in those returning ill or with injuries.

Keywords: Immunisation, travel health, travel medicine, World Health Organization


How to cite this article:
Steffen R. Travel health - Travel medicine. J Health Spec 2017;5:42-4

How to cite this URL:
Steffen R. Travel health - Travel medicine. J Health Spec [serial online] 2017 [cited 2019 Jun 18];5:42-4. Available from: http://www.thejhs.org/text.asp?2017/5/1/42/198796

This is an updated version of lecture held on the occasion of the TRAVAX Anniversary Seminar on 10 September 2015 in Glasgow.


  Historical Introduction Top


Many believe that travel medicine is new. Even if to the best of our knowledge, the term was created and defined in the early 1980s, the concept is old. Already, Shakespeare in As You Like It asked the fundamental epidemiological question:

  • Alas, what danger will it be to us
  • Maids as we are, to travel forth so far?


In Romeo and Juliet, he reasoned about the prophylactic consequences:

  • Nurse, how shall this be prevented?


Let us also remember that centuries ago, James Lind (1716-1794) conducted the first controlled clinical trial in six groups of two navy sailors to determine what would cure scurvy. Among the 12 study patients, those who after 2 months at sea daily for 6 days received 2 oranges and 1 lemon did best, those with a quart of cider had a partially improved condition, whereas sulphuric acid, vinegar, seawater, and spicy paste plus barley water were ineffective.[1]

The goal of travel health-mainly limited to pre-travel health advice and measures-is to keep travellers alive and healthy. Most would also include advice for self-therapy abroad. Travel medicine is broader and includes also diagnosis and treatment in returning travellers.

Until the mid-20th century, there was little need for travel medicine, the main exception being military expeditions, as mentioned above including problems of seafarers and international pilgrimage. With the introduction of jet airliners, particularly of jumbo jet planes, masses of tourists, businessmen/women and other travellers started to cross the oceans and to adventure into countries which had an inferior infrastructure and hygiene as compared to home. In that period, travel vaccine recommendations based on 'experience' were often contradictive; there were no data, there was no evidence base. As late as 1969, public health certificates had to be issued stating that the bearer 'is not suffering from trachoma, leprosy, dysentery, acute epilepsy and insanity'. Concerned about the increasing number of imported infectious diseases, it was recognised in the 1970s in various parts of the world that a systematic assessment of epidemiological data in travellers was essential to be able to conclude on preventive measures to assure their health.[2],[3]


  Current Evidence Base Top


Various studies have demonstrated that accidents are the most frequent cause of death for travellers, particularly in low-income countries;[4] this stands in contrast to destinations in Southern Europe or the Caribbean, where mortality is often associated with cardiovascular or malignant diseases as senior citizens often spend the winters there.

Analysing morbidity, travellers' diarrhoea remains the most frequent health problem, even if the incidence rates have decreased probably due to improved hygienic conditions, particularly in countries with emerging economies and even in low-economy countries in those places where foreign visitors stay.[5] There is an increasing interest on the long-term impact of these gastrointestinal infections, mainly the post-infectious irritable bowel syndrome.[6] In addition, there is a raising concern about the importation of resistant Enterobacteriaceae, particularly after the use of antimicrobials.[7]

With respect to vaccine-preventable diseases, we have data that influenza is particularly frequent, and that typhoid fever is a risk particularly in South Asia and for those visiting friends and relatives (VFRs).[8] The incidence rate of hepatitis A and hepatitis B infections has decreased.[9] There is a low risk of typhoid at other destinations,[10] and only very few cases of cholera, Japanese encephalitis and meningococcal disease are anecdotally reported. Of concern are the many travellers who - mainly after dog bites in countries with rabies endemicity - require post-exposure prophylaxis.[11] The risk of tick-borne encephalitis in Europe should not be neglected: There are far more cases as compared to diagnosed rabies, meningococcal disease or Japanese encephalitis.[12]

In recent years, we have observed a marked decrease in the incidence rate of malaria among travellers to many destinations; of greatest concern now are VFRs during or after stays in tropical Africa.[13],[14] Migrants and refugees arriving from this part of the world also frequently import malaria. In contrast, in Latin America and most Asian destinations, the risk of that infection is now low or very low; but in contrast, other vector-borne diseases, such as dengue,[15] chikungunya and most recently Zika, are of increasing concern.[16]

Finally, we have an early warning system. The International Society of Travel Medicine (ISTM) and the U.S. Centers for Disease Control and Prevention established GeoSentinel, a global surveillance network currently including 57 clinics on five continents. These effectively detect geographic and temporal trends in morbidity among travellers, immigrants and refugees, occasionally even before the national surveillance has realised the problem. Thanks to rapid communication, athletes potentially infected by leptospira during an eco-challenge race in Sabah could be alerted in time.[17] Various interactive websites provide rapidly updated information for the public and/or health professionals.


  Lacking the Evidence Resulting in Relevant Gaps Top


Despite a rapidly increasing number of publications, travel epidemiology is far from where it ideally should be. The World Health Organization (WHO) since 2012 has not published the annual International Travel and Health, as many recommendations were based on data which are graded to be of substandard quality.[18] With respect to mortality, we lack data on fatalities after returning home, be those associated with injuries and infections, mainly malaria; the documentation on pulmonary embolism subsequent to deep vein thrombosis is not conclusive. Uncertainties are also illustrated by the fact that there is no global consensus on the vaccines to be recommended to travellers originating in industrialised countries when the destination is in a developing one. For the development of modern guidelines, we need a risk assessment based on the 21st century state-of-the-art trials.[19]

Other important questions remain unresolved: Is the biologically plausible rule 'boil it, cook it, peel it, or forget it' really useless to avoid diarrhoea abroad?[20] Most studies detected no risk reduction among those who claimed to have followed that old colonial rule - but why? Whether or not antimicrobial agents can still be recommended for self-treatment of travellers' diarrhoea has been debated at a 'Summit Meeting' organised by the Foundation of the ISTM in April 2016 (publication in preparation, Journal of Travel Medicine). There are on-going discussions about the best strategy against malarial infections.[17],[18],[21]


  Outlook Top


The world is changing. Infections such as poliomyelitis or malaria are being eliminated or drastically reduced. Alan Magill, Malaria Program Director at the Bill and Melinda Gates Foundation in 2014, with somewhat provocative vision stated that travel medicine will become unnecessary in a world in which major infectious diseases would be eradicated, in which there would be no more poverty and thus good hygiene. Obviously that would be great, but let us remember that emerging infections, the last being Zika, often get us by surprise and result in a tremendous challenge for travel health professionals. Just in May and June 2016, there was debate as to whether the Summer Olympics in Rio scheduled for August 2016 should be cancelled, postponed or transferred to another location.

Continuous monitoring is essential to be able to give our customers adequate travel health advice. The new generation of health professionals not only need information about prevention, but also about the epidemiological evolution to adequately and rapidly diagnose and treat imported diseases, possibly using new diagnostic tools. Multicentre collaborative studies are needed to establish the evidence base, which the WHO is expecting from us travel health professionals to issue recommendations. In addition, new travel characteristics, mainly medical tourism, will result in new challenges. In contrast, travel to outer space is unlikely to become soon a major issue.

Financial support and sponsorship

Nil.

Conflicts of interest

RS has accepted fees for contributing to education or serving on advisory boards, reimbursement for attending meetings, and/or funds for research from Baxter, Dr. Falk Pharma, GlaxoSmithKline, Intercell (now ValNeva), Novartis Vaccines and Diagnostics, Pfizer, Sanofi Pasteur MSD, Takeda.

 
  References Top

1.
Dunn PM. James Lind (1716-94) of Edinburgh and the treatment of scurvy. Arch Dis Child Fetal Neonatal Ed 1997;76:F64-5.  Back to cited text no. 1
    
2.
Kendrick MA. Study of illness among Americans returning from international travel, July 11-August 24, 1971. (Preliminary data). J Infect Dis 1972;126:684-5.  Back to cited text no. 2
    
3.
Steffen R, van der Linde F, Meyer HE. Risk of disease in 10,500 travelers to tropical countries and 1,300 tourists to North America. Schweiz Med Wochenschr 1978;108:1485-95.  Back to cited text no. 3
    
4.
Jeannel D, Allain Ioos S, Bonmarin I, Capek I, Caserio Schonemann C, Che D, et al. Fatalities of French abroad and their causes. Bull Epidemiol Hebd 2006;23-24:166-8.  Back to cited text no. 4
    
5.
Steffen R, Hill DR, DuPont HL. Traveler's diarrhea: A clinical review. JAMA 2015;313:71-80.  Back to cited text no. 5
    
6.
Connor BA, Riddle MS. Post-infectious sequelae of travelers' diarrhea. J Travel Med 2013;20:303-12.  Back to cited text no. 6
    
7.
Kantele A, Lääveri T, Mero S, Vilkman K, Pakkanen SH, Ollgren J, et al. Antimicrobials increase travelers' risk of colonization by extended-spectrum betalactamase-producing Enterobacteriaceae. Clin Infect Dis 2015;60:837-46.  Back to cited text no. 7
    
8.
Steffen R, Behrens RH, Hill DR, Greenaway C, Leder K. Vaccine-preventable travel health risks: What is the evidence-what are the gaps? J Travel Med 2015;22:1-12.  Back to cited text no. 8
    
9.
Sane J, de Sousa R, van Pelt W, Petrignani M, Verhoef L, Koopmans M. Risk of hepatitis A decreased among Dutch travelers to endemic regions in 2003 to 2011. J Travel Med 2015;22:208-11.  Back to cited text no. 9
    
10.
Committee to Advise on Tropical Medicine and Travel (CATMAT). Statement on International Travellers and Typhoid. Public Health Agency of Canada; 2014. Available from: http://www.publications.gc.ca/collections/collection_2014/aspc-phac/HP40-98-2014-eng.pdf. [Last accessed on 2015 Dec 13].  Back to cited text no. 10
    
11.
Walker XJ, Barnett ED, Wilson ME, Macleod WB, Jentes ES, Karchmer AW, et al. Characteristics of travelers to Asia requiring multidose vaccine schedules: Japanese encephalitis and rabies prevention. J Travel Med 2015;22:403-9.  Back to cited text no. 11
    
12.
Steffen R. Epidemiology of tick-borne encephalitis (TBE) in international travellers to Western/Central Europe and conclusions on vaccination recommendations. J Travel Med 2016;23. pii: Taw018.  Back to cited text no. 12
    
13.
Behrens RH, Neave PE, Jones CO. Imported malaria among people who travel to visit friends and relatives: Is current UK policy effective or does it need a strategic change? Malar J 2015;14:149.  Back to cited text no. 13
    
14.
Field V, Gautret P, Schlagenhauf P, Burchard GD, Caumes E, Jensenius M, et al. Travel and migration associated infectious diseases morbidity in Europe, 2008. BMC Infect Dis 2010;10:330.  Back to cited text no. 14
    
15.
Verschueren J, Cnops L, van Esbroeck M. Twelve years of dengue surveillance in Belgian travellers and significant increases in the number of cases in 2010 and 2013. Clin Microbiol Infect 2015;21:867-72.  Back to cited text no. 15
    
16.
Rocklöv J, Quam MB, Sudre B, German M, Kraemer MU, Brady O, et al. Assessing seasonal risks for the introduction and mosquito-borne spread of Zika virus in Europe. EBioMedicine 2016;9:250-6.  Back to cited text no. 16
    
17.
Centers for Disease Control and Prevention (CDC). Update: Outbreak of acute febrile illness among athletes participating in Eco-Challenge-Sabah 2000-Borneo, Malaysia, 2000. MMWR Morb Mortal Wkly Rep 2001;50:21-4.  Back to cited text no. 17
    
18.
WHO. International Travel and Health. Geneva: World Health Organization; 2012.  Back to cited text no. 18
    
19.
WHO. Handbook for Guideline Development. Geneva: World Health Organization; 2012.  Back to cited text no. 19
    
20.
Shlim DR. Looking for evidence that personal hygiene precautions prevent traveler's diarrhea. Clin Infect Dis 2005;41 Suppl 8:S531-5.  Back to cited text no. 20
    
21.
Schlagenhauf P, Petersen E. Malaria chemoprophylaxis: Strategies for risk groups. Clin Microbiol Rev 2008;21:466-72.  Back to cited text no. 21
    




 

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