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Abstract

  1. Top of page
  2. Abstract
  3. Materials and Methods
  4. Results
  5. Discussion
  6. Note
  7. Acknowledgment
  8. Declaration of Interests
  9. References

Background. About 50 million people travel each year from industrialized countries to destinations in the tropics and subtropics. Among them, there are more than 2 million minors traveling. Although their number is increasing constantly, data on health risks during travel are limited.

Methods. This study analyzed demographic, travel, and clinical data of 890 travelers of age <20 years presenting at the outpatient travel clinic of the University of Munich between 1999 and 2009 after returning from the tropics and subtropics.

Results. Most (87%) of these young travelers were born in Germany. Among them, the main travel destination was Africa (46%), followed by Asia (35%) and Latin America (19%). The most frequent syndrome groups were acute diarrhea (25%, especially in age 0–4 y), dermatologic disorders (21%, especially in age 0–9 y), febrile/systemic diseases (20%), respiratory disorders (8%), chronic diarrhea (5%), and genitourinary disorders (3%). The 10 most frequent diagnosed infectious diseases were giardiasis (8%), schistosomiasis (4%), superinfected insect bites (4%), Campylobacter enteritis (4%), Salmonella enteritis (4%), cutaneous larva migrans (3%), amebiasis (3%), dengue fever (2%), mononucleosis (2%), and malaria (2%). The relative risk (RR) for acquiring any infectious disease during travel was highest in Central, West, and East Africa, followed by South America, South Asia, and Southeast Asia.

Conclusions. Age of young travelers and destination of travel were the most important variables being strongly correlated with the risk for acquiring infectious diseases in the tropics and subtropics. The highest risk was carried by very young travelers and those staying in sub-Saharan Africa (except Southern Africa).

According to the United Nations World Tourism Organization, more than 935 million international travels occurred in 2010 and their number is increasing continuously.1 About 50 million people travel each year from industrialized countries to tropical or subtropical destinations.2 Although estimations on the number of children traveling internationally are limited, travel data for US residents indicate that about 1.5 to 2 million US Americans of age under 16 years travel annually to tropical or subtropical countries.3,4 In the UK, imported diseases account for 2% of pediatric hospitalization.5 Physicians have to be aware that potential pathogens differ in various factors, such as the population of travelers,6,7 the travel destination,8,9 and the incubation period of pathogens typical or specific for the tropics and subtropics.10–12

Travel medicine standards are increasingly based on evidence and moving away from reliance on single expert opinions. Nevertheless, previous studies on pediatric travel-related morbidity were using post-travel questionnaires13,14 or consisted only of small study populations from single centers with focus on individual diseases.15–20 A certain number of multicentric reviews were performed; however, most of them focused on the demographic characteristics21 and on diagnoses without linking them to the symptoms presented by young patients returning from travel.

This study analyzes systematically demographic, travel, and clinical data of travelers of age <20 years returning from tropical and subtropical countries and presenting at the outpatient travel clinic of the Department of Infectious Diseases and Tropical Medicine (DITM) in Munich, Germany. Stratified into age groups, the study describes the spectrum of imported infectious diseases and syndromes among the study population. Furthermore, it evaluates the risk for acquiring infectious diseases and syndromes for different travel destinations.

Materials and Methods

  1. Top of page
  2. Abstract
  3. Materials and Methods
  4. Results
  5. Discussion
  6. Note
  7. Acknowledgment
  8. Declaration of Interests
  9. References

Study Population and Inclusion Criteria

From January 1999 through December 2009, 42,863 patients with symptoms or individuals for medical checkup presented at the DITM, including 2,558 (6.0%) individuals of age <20 years. Two criteria were defined to include them into this study: the individuals who had a clinically or laboratory confirmed diagnosis (1,380 subjects fulfilled criteria: 53.9%) and the individuals who had traveled to a tropical or subtropical country before presentation (1,173 subjects fulfilled criteria: 45.9%). Overall, 890 (34.8%) travelers of age <20 years fulfilled both criteria (study population). Among them, 687 (77.2%) individuals had a national health insurance [419 (47.1%) with referrals from physicians of former consultations, 268 (30.1%) individuals without referrals]. The consultation fees of the remaining 203 (22.8%) individuals were paid otherwise (eg, private health insurance, privately, employers of parents, or others).

Analyzed Variables

Demographic data [sex, age, and origin (country of birth)] were analyzed for the whole study population of 890 travelers (Table 1). Data on travel (destination, duration, and type of travel) and clinical data (symptom at presentation, syndrome, and infectious disease) were analyzed only among 774 travelers with German origin to avoid confounding by country of origin (Tables 2 and 3). The patients' symptoms and diagnoses of infectious diseases were categorized into seven syndrome groups, according to a standardized list of >500 diagnoses of infectious diseases as previously described by Freedman et al.8 Data of the study population were analyzed after stratification into age groups of 0 to 4 years (AG0–4), 5 to 9 years (AG5–9), 10–14 years (AG10–14), and 15–19 years (AG15–19).

Table 1.  Demographic data of 890 travelers of age <20 years presenting for the first time at the outpatient travel clinic of the Department of Infectious Diseases and Tropical Medicine (DITM) of the University of Munich, Germany, between 1999 and 2009
VariablesAge groupsTotal p Value*
0–4 y (%)5–9 y (%)10–14 y (%)15–19 y (%)
  1. na = not applicable.

  2. *Chi-square test or Fisher's exact test: p value comparing the proportions of each condition of all variables listed above in four age groups. Significant p values: defined as p < 0.05. No calculation of p values in subgroups with n < 5 travelers.

  3. Western Europe without Germany.

  4. North America defined as individuals originally from the United States of America and Canada.

Travelers191 (21.5)173 (19.4)134 (15.1)392 (44.0)890 (100)na
Sex: Male117 (61.3)96 (55.5)84 (62.7)151 (38.5)448 (50.3)<0.01
Origin
 Germany165 (86.4)156 (90.2)122 (91.0)331 (84.4)774 (87.0)0.12
 Africa9 (4.7)6 (3.5)5 (3.7)28 (7.1)48 (5.4)0.21
 Western Europe4 (2.1)4 (2.3)1 (0.7)15 (3.8)24 (2.7)0.24
 Asia4 (2.1)4 (2.3)2 (1.5)5 (1.3)15 (1.7)0.79
 Latin America4 (2.1)2 (1.2)2 (1.5)5 (1.3)13 (1.5)0.86
 North America3 (1.6)0 (0)0 (0)3 (0.8)6 (0.7)0.22
 Eastern Europe2 (1.0)1 (0.6)1 (0.7)1 (0.3)5 (0.6)0.67
 Oceania0 (0)0 (0)0 (0)4 (1.0)4 (0.4)na
 Unknown0 (0)0 (0)1 (0.7)0 (0)1 (0.1)na
Table 2.  Travel data of 774 travelers of age <20 years with German origin presenting for the first time at the outpatient travel clinic of the Department of Infectious Diseases and Tropical Medicine (DITM) of the University of Munich, Germany, between 1999 and 2009
VariablesAge groupsTotal p Value*
0–4 y (%)5–9 y (%)10–14 y (%)15–19 y (%)
  1. na = not applicable; ATB = Adventure travel and backpacking including other tourist travels with low hygienic standard; VFR = Visiting friends and relatives; Package tour = Package tour including other tourist travels with high hygienic standard.

  2. *Chi-square test or Fisher's exact test: p value comparing the proportions of each condition of all variables listed above in four age groups. Significant p values: defined as p < 0.05.

  3. Type of travel regarding the parents, if young traveler stayed abroad with parents or regarding the young traveler himself/herself, if young traveler stayed abroad without parents.

Travelers165(21.3)156(20.2)122(15.8)331(42.8)774(100)na
Destination
 Africa70(42.4)85(54.5)64(52.5)140(42.3)359(46.4)0.03
 Asia58(35.2)45(28.8)40(32.8)126(38.1)269(34.8)0.24
 Latin America37(22.4)26(16.7)18(14.8)65(19.6)146(18.9)0.34
Duration of travel
 Unknown3(1.8)1(0.6)2(1.6)8(2.4)14(1.8)0.59
 Known162(98.2)155(99.4)120(98.4)323(97.6)760(98.2)0.59
 (100)(100)(100)(100)(100) 
 1–14 d34(21.0)41(26.5)40(33.3)107(33.1)222(29.2)0.03
 15–28 d42(25.9)54(34.8)47(39.2)99(30.7)242(31.8)0.08
 >28 d86(53.1)60(38.7)33(27.5)117(36.2)296(38.9)<0.01
Type of travel      
 ATB37(22.4)37(23.7)34(27.9)145(43.8)253(32.7)<0.01
 VFR75(45.5)62(39.7)41(33.6)50(15.1)228(29.5)<0.01
 Package tour24(14.5)33(21.2)28(23.0)62(18.7)147(19.0)0.28
 Business trip12(7.3)11(7.1)13(10.7)14(4.2)50(6.5)0.09
 Immigration9(5.5)6(3.8)3(2.5)14(4.2)32(4.1)0.65
 Missionary/volunteer2(1.2)2(1.3)0(0)19(5.7)23(3.0)<0.01
 Exchange program0(0)0(0)0(0)17(5.1)17(2.2)<0.01
 Others6(3.6)5(3.2)3(2.5)10(3.0)24(3.1)0.95
Table 3.  Clinical data of the 774 travelers of age <20 years with German origin presenting with 823 diagnoses (categorized into the six most frequent syndrome groups) for the first time at the outpatient travel clinic of the Department of Infectious Diseases and Tropical Medicine (DITM) of the University of Munich, Germany, between 1999 and 2009
VariablesAge groupsTotal p Value*
0–4 y (%)5–9 y (%)10–14 y (%)15–19 y (%)
  1. na = not applicable; GID = gastrointestinal diseases.

  2. *Chi-square test or Fisher's exact test: p value comparing the proportions of each condition of all variables listed above in four age groups. Significant pvalues: defined as p < 0.05.

  3. Only first diagnosis of 774 young travelers of age <20 years were considered. Only infectious diseases with five or more subjects are listed here.

  4. Schistosomiasis: Five infections with Schistosoma haematobium and two infections with Schistosoma mansoni. The remaining 25 cases were confirmed by serological testing only.

  5. §Amebiasis: 17 intestinal infections with Entamoeba dispar and 2 intestinal infections with Entamoeba histolytica. No case of liver abscess.

  6. Syndrome groups are defined as previously described in Ref. 8. Erratum in N. Engl J Med 2006; 355:967. Among 774 young travelers, 729 (94.2%) travelers presented with one disease, 41 (5.3%) travelers with two diseases, and 4 (0.5%) travelers with three diseases. Others include injury and musculoskeletal, dental, psychological, neurological, ophthalmological diseases, gastrointestinal disorders other than diarrhea, and tissue parasite.

Infectious diseases      
 Total165(100)156(100)122(100)331(100)774(100)na
 (21.3)(20.2)(15.8)(42.8)(100) 
 Giardiasis10(6.1)12(7.7)6(4.9)34(10.3)62(8.0)0.19
 Schistosomiasis1(0.6)11(7.1)5(4.1)15(4.5)32(4.1)0.03
 Superinfected insect bites8(4.8)9(5.8)4(3.3)9(2.7)30(3.9)0.36
 Campylobacter enteritis7(4.2)1(0.6)3(2.5)18(5.4)29(3.7)0.06
 Salmonella enteritis10(6.1)3(1.9)6(4.9)8(2.4)27(3.5)0.10
 Cutaneous larva migrans6(3.6)7(4.5)3(2.5)8(2.4)24(3.1)0.61
 Amebiasis§5(3.0)2(1.3)2(1.6)10(3.0)19(2.5)0.59
 Dengue fever0(0)2(1.3)8(6.6)8(2.4)18(2.3)<0.01
 Mononucleosis0(0)1(0.6)3(2.5)13(3.9)17(2.2)0.02
 Malaria4(2.4)1(0.6)4(3.3)6(1.8)15(1.9)0.43
 Shigella enteritis1(0.6)5(3.2)4(3.3)1(0.3)11(1.4)0.02
Syndrome groups
 Total174(100)161(100)121(100)367(100)823(100)na
 (21.1)(19.6)(14.7)(44.6)(100) 
 Acute diarrhea55(31.6)29(18.0)27(22.3)91(24.8)202(24.5)0.03
 Dermatologic disorders43(24.7)45(28.0)18(14.9)65(17.7)171(20.8)0.01
 Febrile/systemic diseases25(14.4)33(20.5)31(25.6)74(20.2)163(19.8)0.12
 Respiratory disorders16(9.2)13(8.1)11(9.1)29(7.9)69(8.4)0.95
 Chronic diarrhea8(4.6)4(2.5)6(5.0)21(5.7)39(4.7)0.45
 Genitourinary disorders1(0.6)4(2.5)3(2.5)17(4.6)25(3.0)0.07
 Others26(14.9)33(20.5)25(20.7)70(19.1)154(18.7)0.52

Estimated RR for Travelers

The RR of any disease among returned travelers was estimated as follows: division of ratio 1 by ratio 2. Ratio 1 was calculated as follows: division of the number of cases (age < 20 y) with any disease returning from a certain travel destination (in the numerator) by the number of air passengers (any age) flying from Germany to the same travel destination (in the denominator) in the year 2008 (Federal Bureau of Statistics, 2008). Ratio 2 was calculated as follows: division of the number of cases (age < 20 y) with any disease returning from the tropics or subtropics (in the numerator) by the number of air (any age) passengers flying from Germany to the tropics or subtropics (in the denominator) in the year 2008 (Federal Bureau of Statistics, 2008; Table 4).

Table 4.  Travel risk analysis of 774 travelers of age <20 years with German origin presenting with 823 diagnoses (categorized into the six most frequent syndrome groups) for the first time at the Department of Infectious Diseases and Tropical Medicine (DITM) of the University of Munich, Germany, between 1999 and 2009
Region of destinationSyndrome group*TotalNo. of air passengers (Million)RR
Sub-region of destinationAcute diarrheaDermatologic disordersFebrile/systemic diseasesRespiratory disordersChronic diarrheaGenitourinary disordersOthers
Country of destinationNo. (%)No. (%)No. (%)No. (%)No. (%)No. (%)No. (%)No. (%)
  1. CA = Central America.

  2. *Syndrome groups are defined as previously described in Ref. 8. Among 774 young travelers, 729 (94.2%) travelers presented with one disease, 41 (5.3%) travelers with two diseases, and 4 (0.5%) travelers with three diseases. Others include injury and musculoskeletal, dental, psychological, neurological, ophthalmological diseases, gastrointestinal disorders other than diarrhea, and tissue parasite.

  3. Official total number of air passengers from Germany traveling to tropical and subtropical regions in Asia, Africa, and Latin America in 2008: 12,274,352 [Statistisches Bundesamt, Federal Bureau of Statistics, Wiesbaden, Germany].

  4. The relative risk (RR) of any disease among returned travelers was estimated as follows: division of ratio 1 by ratio 2. Ratio 1 was calculated as follows: division of the number of cases (age < 20 y) with any disease returning from a certain travel destination (in the numerator) by the number of air passengers (any age) flying from Germany to the same travel destination (in the denominator) in the year 2008 (Federal Bureau of Statistics, 2008). Ratio 2 was calculated as follows: division of the number of cases (age < 20 y) with any disease returning from the tropics or subtropics (in the numerator) by the number of air (any age) passengers flying from Germany to the tropics or subtropics (in the denominator) in the year 2008 (Federal Bureau of Statistics, 2008).

Africa98(48.5)68(39.8)79(48.5)30(43.5)16(41.0)10(40.0)86(55.8)387(47.0)3.5561.62
 West Africa26(12.9)28(16.4)29(17.8)10(14.5)4(10.3)2(8.0)23(14.9)122(14.8)0.1919.53
 East Africa24(11.9)22(12.9)35(21.5)13(18.8)3(7.7)2(8.0)22(14.3)121(14.7)0.2906.22
 North Africa39(19.3)7(4.1)8(4.9)1(1.4)5(12.8)4(16.0)22(14.3)86(10.4)2.4230.53
 Central Africa4(2.0)2(1.2)2(1.2)3(4.3)2(5.1)1(4.0)11(7.1)25(3.0)0.01820.71
 Southern Africa5(2.5)9(5.3)5(3.1)3(4.3)2(5.1)1(4.0)8(5.2)33(4.0)0.6340.78
Asia75(37.1)54(31.6)63(38.7)23(33.3)13(33.3)7(28.0)44(28.6)279(33.9)7.1160.58
 South Asia32(15.8)22(12.9)27(16.6)7(10.1)8(20.5)2(8.0)21(13.6)119(14.5)1.1331.57
 Southeast Asia40(19.8)29(17.0)30(18.4)15(21.7)4(10.3)3(12.0)19(12.3)140(17.0)1.4781.41
 East Asia1(0.5)1(0.6)1(0.6)1(1.4)1(2.6)0(0)3(1.9)8(1.0)2.4580.05
 West Asia2(1.0)1(0.6)2(1.2)0(0)0(0)0(0)1(0.6)6(0.7)1.8550.05
 Central Asia0(0)1(0.6)3(1.8)0(0)0(0)2(8.0)0(0)6(0.7)0.1920.47
Latin America29(14.4)49(28.7)21(12.9)16(23.3)10(25.6)8(32.0)24(15.6)157(19.1)1.6021.46
 CA/Caribbean10(5.0)17(9.9)6(3.7)5(7.2)4(10.3)4(16.0)8(5.2)54(6.6)0.8120.99
 South America19(9.4)32(18.7)15(9.2)11(15.9)6(15.4)4(16.0)16(10.4)103(12.5)0.7911.94
Total202(100)171(100)163(100)69(100)39(100)25(100)154(100)823(100)12.2741.00
 (24.5)(20.8)(19.8)(8.4)(4.7)(3.0)(18.7)(100)  

Statistical Analysis

Approximative tests (χ2-tests) were conducted using Stata software, version 9.0. (Stata Corporation, College Station, TX, USA) and EpiInfo, version 3.3.2. (Centers for Disease Control and Prevention, CDC, Atlanta, GA, USA). Significant differences were defined as p values below 0.05.

Results

  1. Top of page
  2. Abstract
  3. Materials and Methods
  4. Results
  5. Discussion
  6. Note
  7. Acknowledgment
  8. Declaration of Interests
  9. References

Demographic Data

In the study population of 890 travelers, 191 travelers (21.5%) were in AG0–4, 173 (19.4%) in AG5–9, 134 (15.1%) in AG10–14, and 392 (44.0%) in AG15–19. The proportion of males was 50.3% (448), whereas it was significantly higher (p < 0.01 each) in AG0–4 and AG10–14. The great majority of patients (774: 87.0%) were born in Germany (German origin), followed by those born in Africa (48: 5.4%), Western Europe (without Germany; 24: 2.7%), and Asia (15: 1.7%) (Table 1).

Travel Data

Among the 774 travelers with German origin, 359 (46.4%) were travelers returning from Africa, 269 (34.8%) from Asia, and 146 (18.9%) from Latin America. In age 5 to 14 years, significantly (p = 0.03) more travelers returned from Africa (149/278: 53.6%).

From 760 (98.2%) travelers, the duration of travel was known. Among them, 222 (29.2%) travelers had been abroad for 1 to 14 days, whereas that proportion was significantly higher (p = 0.03) in AG10–14 (33.3%) and AG15–19 (33.1%). Furthermore, 296 (38.9%) travelers had been abroad for >28 days, whereas that proportion was significantly higher (p < 0.01) in AG0– 4 (53.1%). Adventure travel and backpacking (including other tourist travels with low hygienic standard; 253: 32.7%) were the most frequent types of travel, whereas that proportion was significantly higher (p < 0.01) in AG15–19 (43.8%). Visiting friends and relatives (VFR; 228: 29.5%) was the second most preferred type of travel and its proportion was significantly higher (p < 0.01) in AG0–4. In this study, whether the young travelers had been abroad with or without parents was not evaluated (Table 2).

Symptoms

Among those 774 travelers, the most frequent symptom was diarrhea (255: 32.9%), followed by fever (216: 27.9%), dermatologic disorders (181: 23.4%), dyspnea (38: 4.9%), and arthralgia (27: 3.5%). From 541 travelers, the onset of their symptoms was known: 28 (5.2%) had the onset on day of return, 237 (43.8%) before, and 276 (51.0%) after return. The most (222: 41.0%) had the onset within 2 months after return.

Among 255 patients with diarrhea, 220 (86.3%) presented with acute diarrhea (duration <14 d), mainly caused by Giardia, Campylobacter, and Salmonella spp. In AG15–19, the prevalence of travelers with genitourinary disorders (3.0%) was significantly higher (p = 0.04), due to five cases of urinary tract infection, three cases of vaginitis, and two cases of herpes genitalis.

Among 216 travelers with fever, 127 (58.8%) travelers presented with febrile/systemic diseases, mainly malaria, mononucleosis, and dengue fever. In AG10–14 and AG15–19, the prevalence of travelers with mononucleosis (2.5 and 2.4%) was significantly higher (p = 0.048), and in AG10–14, the prevalence of travelers with dengue fever (4.9%) was significantly higher (p < 0.01). Among the 216 travelers with fever, 89 (41.2%) travelers presented with acute diarrhea, mainly caused by Salmonella, Campylobacter, and Entamoeba spp. In AG0–4, the prevalence (17.0%) of travelers with acute diarrhea was significantly higher (p < 0.01).

Among 181 travelers with dermatologic disorders, symptoms were mainly caused by insect bites (44 cases; 30 of them were bacterially superinfected) and cutaneous larva migrans (24 cases), whereas no significant differences were found between the age groups (Table 3). Among 38 travelers with dyspnea, no cases with specific pathogens were detected. Among 27 travelers with arthralgia, 4 patients had dengue fever.

Infectious Diseases

Among those 774 travelers, the most frequent diagnoses were giardiasis (62: 8.0%) and insect bites (44: 5.7%; bacterially superinfected: 30: 3.9%). In AG5–9, the prevalence of schistosomiasis (7.1%) was significantly (p = 0.03) higher; in AG10–14, the prevalence of dengue fever (6.6%) and of Shigella enteritis (3.3%) was significantly (p < 0.01 and 0.02) higher; in AG15–19, the prevalence (3.9%) of mononucleosis was significantly (p = 0.02) higher (Table 3).

Syndrome Group and Travel Destination

Among those 774 travelers, 823 diagnoses were detected during presentation, because 729 (94.2%) travelers had one diagnosis, 41 (5.3%) travelers had two diagnoses, and 4 (0.5%) travelers had three diagnoses, which were categorized into syndrome groups. The most frequent syndrome groups were acute diarrhea (202: 24.5%), dermatologic disorders (171: 20.8%), and febrile/systemic diseases (163: 19.8%).

Among all 823 syndromes, 387 (47.0%) were detected in travelers returning from Africa. This prevalence was highest among cases of acute diarrhea (98/202: 48.5%) and of febrile/systemic diseases (79/163: 48.5%). The following infectious diseases were diagnosed most frequently. Among 98 travelers with acute diarrhea: Giardiasis (13), amebiasis (8), Salmonella enteritis (6), and Shigella enteritis (5); among 79 travelers with febrile/systemic diseases: Schistosomiasis (23) and acute hepatitis A (3).

Furthermore, 279 (33.9%) syndromes were detected in travelers returning from Asia. This prevalence was highest among cases of febrile/systemic diseases (63/163: 38.7%) and of acute diarrhea (75/202: 37.1%). The following infectious diseases were diagnosed most frequently. Among 63 travelers with febrile/systemic diseases: dengue fever (12 cases), mononucleosis (10), malaria (9), and paratyphoid fever (5); among 98 travelers with acute diarrhea: Campylobacter enteritis (12), Salmonella enteritis (10), giardiasis (5), shigella enteritis (4), and cryptosporidiosis (4).

Finally, 157 (19.1%) syndromes were detected in travelers returning from Latin America. This prevalence was highest among cases of genitourinary disorders (8/25: 32.0%), of dermatologic disorders (49/171: 28.7%), and of chronic diarrhea (10/39: 25.6%). The following infectious diseases were diagnosed most frequently. Among eight travelers with genitourinary disorders: herpes genitalis (2); among 49 travelers with dermatologic disorders: cutaneous larva migrans (12), insect bites (7), fungal dermatologic disorders (6), and tungiasis (2); among 10 travelers with chronic diarrhea, no specific pathogen was detected (Table 4).

Estimated RR for Young Travelers

Among the 774 travelers with German origin, 823 diagnoses were detected during presentation and classified into syndrome groups as previously described by Freedman et al.8 Their RR for any infectious disease was highest for travels to Central (RR = 20.71), West (9.53), and East Africa (6.22), followed by South America (1.94), and South Asia (1.57), compared with mean RR (reference, RR = 1.0, Table 4).

Discussion

  1. Top of page
  2. Abstract
  3. Materials and Methods
  4. Results
  5. Discussion
  6. Note
  7. Acknowledgment
  8. Declaration of Interests
  9. References

This is one of the largest studies on imported infectious diseases among young travelers returning from tropical and subtropical countries. The study analyzed demographic, travel, and clinical data of travelers of age <20 years and assessed risk factors for acquiring infectious diseases during traveling after stratifying the data into four age groups. Out of 2,558 individuals of age <20 years presenting at the outpatient travel clinic of the University of Munich between 1999 and 2009, 890 travelers (35%) returned from tropical and subtropical destinations and had a clinically or laboratory confirmed diagnosis.

The variable sex was not significantly correlated with any imported infectious disease, whereas it seemed to be for the variables age and origin. Consequently, data were analyzed by stratifying into age groups and further analysis was performed with travelers of German origin only to avoid confounding. However, 30% of young travelers born in Germany were abroad for visiting friends and relatives, thus we suppose that the majority of these travelers have parents who had migrated to Germany before.

Analysis on travelers with German origin has not shown any significant correlation between type of travel and acquired infectious disease; also there was no significant correlation found between the type of travel “visiting friends and relatives” and destination or the risk to acquire a certain infectious disease. Among 48 travelers of African origin, almost all (47: 98%) traveled to Africa and acquired infectious diseases which are highly endemic there, such as malaria (5 cases), schistosomiasis (6 cases), and diarrheal diseases (23 cases). The correlation between African origin and these infectious diseases was highly confounded by travel destination. For travelers with other origins, sample size was low and no correlation with any infectious disease was found.

Among the very young travelers of age 0 to 4 years, the duration of travel was significantly longer than that for travelers of age 5 to 19 years. This result was caused by the fact that almost half of the parents with children of age 0 to 4 years stayed abroad for visiting friends and relatives. In the age group 0 to 4 years, the risk for diarrhea, especially acute diarrhea, was higher than in the age group 5 to 14 years, as shown in other studies.21,22

Among the travelers of age 5 to 9 years, the risk for acquiring schistosomiasis was significantly higher than that for travelers of the other age groups. This result is caused by the fact that more travelers in that age group stayed in Africa, where schistosomiasis is highly endemic in many regions.

In this study, the following trends depending on the age of young travelers were found. With decreasing age, there was an increasing duration of travel, increasing number of travelers visiting friends and relatives abroad, and increasing risk for acquiring acute diarrhea and dermatologic disorders during travel. Furthermore, with increasing age, there was an increasing number of backpackers (as teenagers prefer traveling by backpacking) and increasing risk for acquiring mononucleosis (as teenagers have an elevated risk mainly caused by kissing) abroad.

Besides mononucleosis, dengue fever and malaria were the most frequently detected febrile/systemic diseases, whereas the majority of dengue fever cases were imported by young travelers from Asia (especially in age group 10–14 y) and the majority of malaria cases from sub-Saharan Africa with steady pattern of distribution among the age groups.23

Dermatologic disorders were mainly caused by insect bites and cutaneous larva migrans, which are diseases that can be prevented by some simple precaution.24,25 However, the number of causes for dermatologic disorders was large and an elevated risk for travelers <10 years.

In general, children of age <10 years showed a distribution pattern of infectious diseases and syndrome groups similar to the one described by previous studies about pediatric travelers6,21 while travelers of age 10 to 19 years matched the distribution patterns found in adults (own unpublished data from about 20,000 returned adult travelers).6,8

The principal variable influencing the risk for acquiring infectious diseases among young travelers was destination of travel. The highest overall risk was carried by young travelers staying in Central, West, and Eastern Africa, followed by South America and South/Southeast Asia. In sub-Saharan Africa (except Southern Africa) and South/Southeast Asia, the most frequent health problems among young travelers were diarrhea and febrile/systemic diseases, mainly due to an elevated risk for malaria in sub-Saharan Africa (except Southern Africa) and for dengue fever in South/Southeast Asia, whereas for young travelers in South America, diarrhea and dermatologic disorders were the most frequent health problems. All these findings correspond to those of other studies.21,26–29

This study had some limitations. Like in previous studies30,31 it was difficult to make specific etiologic diagnoses for all occurred symptoms, especially for diarrhea in which almost 40% of the cases were diagnosed with gastroenteritis, presumably caused by an viral infection.32 No specific diagnostic procedures on rotavirus, norovirus, and Escherichia coli spp. were performed, although these pathogens are frequent causes of travelers' diarrhea.26 However, in contrast to the other studies on large numbers of patients, which were mostly multicentric,7,21 this study provides same conditions for all patients, consistency in coding of diagnoses by clinicians, and central laboratory reference facilities.

Among all variables analyzed in this study, destination of travel and age of traveler were variables highly correlated with the risk for acquiring infectious diseases, which are specific or typical for the tropics and subtropics. Very young travelers were more likely to stay abroad for a long time, to visit friends and relatives, and to carry a higher risk for acquiring acute diarrhea and dermatologic disorders during travel, while travelers of age 10 to 19 years matched the distribution patterns found in adults. The highest overall risk was carried by young travelers staying in sub-Saharan Africa (except Southern Africa).

Note

  1. Top of page
  2. Abstract
  3. Materials and Methods
  4. Results
  5. Discussion
  6. Note
  7. Acknowledgment
  8. Declaration of Interests
  9. References

The GeoSentinel Surveillance Network (GSN) has published data on diseases among returned travelers of age <18 years.21 In that publication, data from 1,591 patients who presented for care in 41 sites in 19 countries situated in 6 different continents between January 1997 and November 2007 were summarized and analyzed. In this study, data from 890 patients of age <20 years who presented for care at one site only, at the DITM of the University Munich between January 1999 and December 2009, were analyzed. As DITM is a member site of GSN, a very small part of the present data has already been published.21

Acknowledgment

  1. Top of page
  2. Abstract
  3. Materials and Methods
  4. Results
  5. Discussion
  6. Note
  7. Acknowledgment
  8. Declaration of Interests
  9. References

The authors thank all patients in this study for their cooperation.

Declaration of Interests

  1. Top of page
  2. Abstract
  3. Materials and Methods
  4. Results
  5. Discussion
  6. Note
  7. Acknowledgment
  8. Declaration of Interests
  9. References

The authors state that they have no conflicts of interest to declare.

References

  1. Top of page
  2. Abstract
  3. Materials and Methods
  4. Results
  5. Discussion
  6. Note
  7. Acknowledgment
  8. Declaration of Interests
  9. References