This study was presented in part at the 12th Conference of the International Society of Travel Medicine (CISTM12), Boston, USA, May 8 to 12, 2011.
The Reliability of Pre-travel History to Decide on Appropriate Counseling and Vaccinations: A Prospective Study
Article first published online: 4 SEP 2012
© 2012 International Society of Travel Medicine
Journal of Travel Medicine
Volume 19, Issue 5, pages 284–288, September/October 2012
How to Cite
Rossi, I. A. and Genton, B. (2012), The Reliability of Pre-travel History to Decide on Appropriate Counseling and Vaccinations: A Prospective Study. Journal of Travel Medicine, 19: 284–288. doi: 10.1111/j.1708-8305.2012.00618.x
- Issue published online: 4 SEP 2012
- Article first published online: 4 SEP 2012
Although medical and travel plans gathered from pre-travel interviews are used to decide the provision of specific pre-travel health advice and vaccinations, there has been no evaluation of the relevance of this strategy. In a prospective study, we assessed the agreement between pre-travel plans and post-travel history and the effect on advice regarding the administration of vaccines and recommendations for malaria prevention.
We included prospectively all consenting adults who had not planned an organized tour. Pre- and post-travel information included questions on destination, itineraries, departure and return dates, access to bottled water, plan of bicycle ride, stays in a rural zone, and close contact with animals. The outcomes measured included: agreement between pre- and post-travel itineraries and activities; and the effect of these differences on pre-travel health recommendations, had the traveler gone to the actual versus intended destinations for actual versus intended duration and activities.
Three hundred and sixty-five travelers were included in the survey, where 188 (52%) were males (median age 38 years). In 81(23%) travelers, there was no difference between pre- and post-travel history. Disagreement between pre- and post-travel history were the highest for stays in rural zones or with local people (66% of travelers), close contact with animals (33%), and bicycle riding (21%). According to post-travel history, 125 (35%) travelers would have needed rabies vaccine and 9 (3%) typhoid fever vaccine. Potential overprovision of vaccine was found in <2% of travelers. A change in the malaria prescription would have been recommended in 18 (5%) travelers.
Pre-travel history does not adequately reflect what travelers do. However, difference between recommendations for the actual versus intended travel plans was only clinically significant for the need for rabies vaccine. Particular attention during pre-travel health counseling should focus on the risk of rabies, the need to avoid close contact with animals and to seek care for post-exposure prophylaxis following an animal bite.
Travel overseas may carry health risks that do not exist in industrialized countries. Appropriate prophylactic measures and vaccinations given on the basis of pre-travel risk assessment can prevent many travel-related illnesses. Ideally pre-travel health counseling is based on the traveler's health history and immunization status, planned or intended activities, destinations, itinerary, and duration of travel.[2, 3]
Although medical and travel plans gathered from pre-travel interviews are used to decide the provision of specific pre-travel health advice and vaccinations, there has been no evaluation of the relevance of this strategy. Indeed it is expected that travelers will change some of their plans (destination, duration, or planned activities) while traveling, but it is not known to what extent differences between intended and actual travel plans will affect pre-travel advice.
In a prospective study, we assessed the agreement between pre-travel plans (intended plans) and post-travel history (real or actual trip). In case of disagreement we assessed the expected effect on the recommendation for travel-related vaccines and malaria prevention.
During pre-travel consultation, we prospectively recruited all consenting adults (>16 years old) who had not planned an organized tour. Only one person per couple was included. The study took place at the Travel Clinic, Department of Ambulatory Care and Community Medicine, University of Lausanne, Switzerland from February 2008 up to February 2009. Participants gave informed consent and were asked to complete a small questionnaire for demographics, telephone number(s), and email address.
Pre- and and post-travel information included questions on destination, itineraries, departure and return dates, access to bottled water, plans to bicycle ride, stays in a rural zone or with local people, and close contact with animals. These variables were chosen because they determined travel-related disease risks and specific recommendations for vaccines or malaria prevention. The traveler's access to bottled water was a measure to be associated with typhoid vaccine recommendations; plans to bicycle ride or to have close contact with animals was associated with rabies vaccine; and stays in rural zones was associated with Japanese encephalitis or meningitis vaccine (Asia and sub-Saharan Africa, respectively).
Pre-travel information was extracted from travel clinic electronic files, where this information is systematically entered to decide on the administration of vaccines and recommendations for malaria prevention. Post-travel information included the same questions as those asked during the pre-travel interview, and was collected using phone calls or email (up to 1 month after return). Outcomes measures included: (1) agreement between pre- and post-travel history, and (2) changes in pre-travel recommendations that would have been expected to occur based on the actual trip (ie, the actual destinations and travel-related activities). In Switzerland, pre-travel health counseling is based on recommendations from the Swiss Commission of Travel Medicine and published by the Swiss Federal Office for Public Health.
Professions were categorized according to the International Standard Classification of Occupations from the International Labor Organization (ISCO-08) and grouped into three classes: (1) managers and intellectual professions, (2) superior administrative and technical professions, and (3) workers and farmers. Two more classes were added to our categories, namely (4) jobless, pensioners, and not known, and (5) students.
The data were anonymously entered in EpiData and transferred to Stata 11.1 for analysis.
In terms of sample size, we expected a lack of agreement between pre-travel visit and post-travel history for about 25% of the cases. Assuming that we wanted to detect an absolute deviation from this rate of 5% with a type I error level of 5% and a power of 80%, the number of patients to be included in the study was 563.
The protocol was approved by the ethics committee of the University of Lausanne.
From a total of 365 travelers enrolled in the study, 356 (98%) subjects could be contacted by telephone or email upon returning home. The characteristics of the 365 included travelers are presented in Table 1.
|Median (range)||33 (16–79)|
|Sub-Saharan Africa||21 (5.8)|
|Manager/intellectual professions||147 (40.3)|
|Administrative or technical professions||95 (26.0)|
|Farmers, workers||32 (8.8)|
|Jobless, pensioners, unknown professions||44 (12.2)|
Regions visited included (in decreasing frequency): sub-Saharan Africa (36.4%), South and/or Central America (24.4%), Southeast Asia and/or Pacific (22.5%), Indian subcontinent (15.1%), and other regions (5.5%) (Table 2). Most frequent reasons for travel included (in decreasing frequency): tourism (77.8%), visiting friends and relatives (17.5%), or for professional reasons (14.5%). Median length of travel was 3 weeks. Most travelers went with their partner (32.6%), while the remaining traveled alone (22.2%), with friends (19.5%), or with the family (13.7%).
|Sub-Saharan Africa||133 (36.4)|
|South and Central America||89 (24.4)|
|Southeast Asia/Pacific||82 (22.5)|
|Indian subcontinent||55 (15.1)|
|Reasons for travel|
|Visit friends and relatives||64 (17.5)|
|Hajj pilgrims||1 (0.3)|
|Not available||5 (1.4)|
|Length of travel median = 3 weeks|
|1 week||11 (3.0)|
|2 weeks||75 (20.6)|
|3 weeks||117 (32.1)|
|4–6 weeks||107 (29.3)|
|>6 weeks||55 (15.1)|
In 81 (22.8%) travelers, there was no difference between pre- and post-travel history (ie, there was close agreement between the intended and actual travel plans). We assessed the number of discordances between pre- and post-travel health assessment for five items, specifically: destination country(ies), length of stay, access to bottled water, stays in rural zones or with local people, and close contact with animals. There was one discordance for one of the five items assessed in 124 (34.8%) travelers, two discordances in 96 (27.0%), three in 45 (12.6%), four in 7 (2.0%), and five in 3 (0.8%).
Unlike pre-travel history (ie, intended travel plans), 58 (16.3%) travelers changed the destinations, and 52 (14.6%) changed length of stay; 23 (6.5%) had no access to bottled water but felt they would have access; 71 (19.9%) rode a bicycle but did not plan to do so; 145 (39.9%) stayed in a rural zone or with local people but did not plan to do so; and 112 (31.5%) had close contact with animals, but did plan to avoid animals. Some travelers overestimated their risks during pre-travel visit. Unlike the intended pre-travel plans, 7 (2.0%) subjects actually had access to bottled water, 2 (0.6%) did not ride a bicycle, and 39 (11.0%) did not stay in a rural zone or with local people. Among the three travelers who had planned close contact with animals, none changed travel plans.
Agreement between intended and actual need for specific travel-related vaccines (ie, appropriateness of vaccine recommendations) is detailed in Table 3. One hundred and twenty-five (35.1%) travelers would have actually needed rabies vaccine and 9 (2.5%) typhoid fever vaccine. Overestimation of the need for any travel-related vaccine was found in ≤2% of all subjects. Among the 125 travelers who would have needed rabies vaccine, actual bicycle riding accounted for 30 subjects, actual close contact with animals for 72, and participating in both activities for 23.
|Vaccine||Appropriate||Should have been prescribed||Should not have been prescribed|
|Yellow fever||352 (98.9)||1 (0.3)||3 (0.9)|
|Typhoid fever||342 (96.1)||9 (2.5)||5 (1.4)|
|Meningitis||355 (99.7)||1 (0.3)||0|
|Rabies||224 (62.9)||125 (35.1)||7 (2.0)|
|Japanese encephalitis||353 (99.2)||1 (0.3)||2 (0.6)|
|Hepatitis B||354 (99.4)||2 (0.6)||0|
The recommendation for malaria chemoprophylaxis or stand-by emergency treatment (SBET) prescription was appropriate in 338 (94.9%) subjects, if based on the history from the pre-travel consultation. A change in malaria prescription would have been recommended in 18 (5%) travelers based on the actual travel history. Three of these 18 subjects would have needed malaria chemoprophylaxis, 4 would have needed SBET and 2 of them counseling about personal protective measures because of a “low” (but not “no”) risk of malaria. Two subjects received unnecessary chemoprophylaxis and seven unnecessary SBET based on actual travel history.
When we compared travel and demographic characteristics between travelers who would have needed rabies vaccine and those who did not need rabies vaccine, age less than 45 years old, travel to sub-Saharan Africa, travel to Southeast Asia and/or Pacific, and a travel duration >2 weeks were significantly associated with the need for rabies vaccine in the univariate analysis (Table 4). Only age ≤45 years old and a travel duration >2 weeks remained significantly associated with the need of rabies vaccine in the multiple logistic regression model.
|Prevalence in travelers who would have needed rabies vaccine |
|Prevalence in travelers who did not need rabies vaccine (231)||Odds ratio||95% CI||P value|
|n (%)||n (%)|
|Male||68 (54.4)||117 (50.7)||1.22||0.8–1.9||0.36|
|16–45||103 (82.4)||161 (69.6)||2.04||1.18–3.51||0.009|
|>45||22 (17.6)||70 (30.3)||Ref|
|Switzerland||94 (75.2)||173 (74.9)||Ref||—||—|
|Europe||20 (16.0)||35 (15.2)||1.05||0.57–1.93||0.87|
|Sub-Saharan Africa||5 (4.0)||16 (7.0)||0.58||0.20–1.63||0.29|
|Other||6 (4.8)||7 (3.0)||1.58||0.51–4.85||0.42|
|Manager/intellectual professions||53 (42.4)||93 (40.3)||Ref||—||—|
|Administrative or technical professions||35 (28)||60 (26.0)||1.02||0.60–1.75||0.93|
|Farmers, workers||12 (9.6)||20 (8.7)||1.05||0.48–2.33||0.90|
|Jobless, pensioners, unknown professions||8 (6.4)||28 (12.1)||0.50||0.21–1.19||0.11|
|Students||17 (13.6)||30 (13.0)||0.99||0.50–1.97||0.99|
|Sub-Saharan Africa||36 (28.8)||93 (40.2)||0.60||0.37–0.96||0.03|
|South and Central America||31 (24.8)||52 (22.5)||1.14||0.68–1.89||0.62|
|Southeast Asia/Pacific||36 (28.8)||43 (18.6)||1.77||1.06–2.96||0.03|
|Indian subcontinent||13 (10.4)||40 (17.3)||0.55||0.28–1.08||0.08|
|Asia||9 (7.2)||9 (3.9)||1.91||0.74–4.97||0.18|
|Europe||0 (0)||1 (0.4)||—||—||—|
|Reasons for travel|
|Tourism||101 (80.8)||178 (77.1)||1.25||0.73–2.15||0.41|
|Visit friends and relatives||19 (15.2)||44 (19.1)||0.76||0.42–1.37||0.36|
|Professional/study/missionary/volunteer||16 (13.2)||34 (14.7)||0.85||0.45–1.61||0.62|
|Hajj pilgrims||0||1 (0.4)||—||—||—|
|Not available||2 (1.6)||1 (0.4)||3.73||0.33–41.99||0.25|
|Length of travel|
|0–2 weeks||16 (12.8)||66 (28.6)||Ref|
|>2 weeks||109 (87.2)||165 (71.4)||2.73||1.48–5.01||0.0008|
To the best of our knowledge, this is the first study to look at the agreement between intended and actual travel history, and the potential effect on recommendations due to the differences between the two sets of risk information. We found that agreement between items measuring travel itinerary, duration of travel and so forth between the pre- and post-travel histories was low. However, the effect on preventive measures was only relevant for the recommendation of rabies vaccine. According to the post-travel history, rabies vaccine should have been prescribed in an additional third of travelers. Overestimation of the need for other vaccines and malaria chemoprophylaxis or SBET was negligible.
Our study has some limitations. First, the sample size was smaller than planned. Indeed, we had expected to recruit more than 500 subjects for this study over a 1-year period, but the recruitment of travelers for another concomitant study lowered the number of travelers available for the present investigation. The priority was given to the concomitant study. Second, we have presented a study of consecutive travelers over a 1-year time frame attending one clinic in one country using one set of recommendations. Thus we do not know if these findings are generalizable to other jurisdictions in Switzerland or in the rest of the world. It would be important if other research groups in other countries were able to repeat our study using different travel medicine recommendations to see if the outcomes are similar or different. Third, we may have excluded (or included) too many subjects with inflexible travel plans, as the exclusion criteria was solely based on whether a traveler had a fixed itinerary or not. Other factors such as chronic medical illness or fixed income could have limited a traveler's ability to change their trip substantially. Lastly, we chose to measure only a selected number of factors that we felt may have been affected by changes in travel plans. However, there may have been other vaccine or prophylaxis recommendations that could have been significantly affected (eg, AMS prophylaxis, fitness to travel, etc.).
In our study, the pre-travel history was not a good predictor of a traveler's actual activities overseas. According to pre-travel history, actual travel-related risks were more often underestimated than overestimated. With the exception of recommendations for rabies vaccine, disagreement between the pre- and post-travel history had no major consequences on the need of vaccine prescription. This is probably due to the fact that vaccine recommendations do not rely solely on one planned activity. For example, we typically recommend Japanese encephalitis vaccine only for travelers who spend at least 4 weeks in a rural zone in risk areas of Asia. Since the median duration of travel was 21 days (IQ 3–368 d), many travelers would not have been recommended this vaccine regardless of a change in their planned activities or destination. During the dry season in the countries of the “meningitis belt” of sub-Saharan Africa, travelers are advised to be vaccinated against meningitis independent of other risk factors such as a stay in rural zone or with local people. Unlike Japanese encephalitis and meningitis vaccine, rabies vaccine is indicated when travelers to endemic risk areas plan to ride a bike or have close contact with animals independently from other potential risk factor (eg, spelunking, sleeping outdoors in the jungle, remoteness to adequate medical care).
Travel duration and general destination plans were the most important elements of pre-travel assessment. Travel duration of more than 1 month determined the prescription of most of the vaccines, irrespective of at-risk activities (ie, typhoid fever and hepatitis B, rabies in the Indian subcontinent and meningitis in the countries of the “meningitis belt” of sub-Saharan Africa). General destination plans almost never changed. Among the 58 travelers who changed the destination, only 4 changed the country and continent, 15 traveled to another region within the same country, and all others traveled to alternative countries in the same continent. Little change in general destination plans probably explains the fact that a change in malaria prescription would have been recommended in only 5% of travelers.
The lack of sensitivity to changes in the travel plans (intended versus actual) found in this study might be related to the Swiss recommendations. Since vaccine recommendations often depend on many factors, it is difficult to predict what would have been the effect of the use of recommendations from another country on vaccine recommendations. Vaccine recommendations based on one factor are therefore more sensitive to changes. For example, in France, more Japanese encephalitis vaccine (JEV) would have been recommended to travelers prior to their trips. France's JEV recommendations depend on a traveler participating in outdoor activities in rural areas, which is an independent consideration to the travel duration.
In conclusion, our study shows that intended travel plans may differ significantly from actual plans. To the question of whether this difference had a substantial impact on pre-travel health advice, recommended vaccines, or malaria prophylaxis, our study suggests that only the recommendations for rabies pre-exposure prophylaxis were underestimated. Our findings are compared against the Swiss travel medicine guidelines, and replication of our study in other jurisdictions with different guidance or recommendations would be an important future step.
The authors acknowledge the substantial contribution of an anonymous reviewer. They also thank M. Skerrett and G. Veniat for recruitment of participants and data collection.
Declaration of Interests
The authors state that they have no conflicts of interest. They have not received grants or honoraria from a vaccine manufacturer.
- 4Swiss Federal Office for Public Health. Santé-voyages: vaccinations et mesures antipaludiques. Bull OFSP 2007; 23:404–413. http://www.bag.admin.ch/dokumentation/publikationen/01435/03542/index.html?lang=fr
- 5International Labour Organization International Standard Classification of Occupations from the International Labour Organization (ISCO-08). Geneva, July 2009. Available at: http://www.ilo.org/public/english/bureau/stat/isco/isco08/index.htm (Accessed 2011 Oct 10).