Infection-induced anaemia: a cross-sectional study of 14,636 German travellers aged 20-49 years.

BACKGROUND: Anaemia is a frequently diagnosed condition which can develop as a consequence of numerous factors, including infectious diseases (IDs). Travelling, especially in sub-/tropical regions, leads to an elevated risk of contracting IDs. The aim of our study was to assess the epidemiological significance of IDs in inducing anaemia among a large cohort of returned travellers. METHODS: This was a cross-sectional study in which data on 17,009 returned travellers aged 20-49 years who consulted the travel medicine clinic of the University of Munich between 1999 and 2011 were retrieved and analysed. RESULTS: Of the returned travellers, 8.3 % (6.0 % of males/10.4 % of females) were diagnosed with anaemia. The prevalence of anaemia was significantly elevated among patients of African (21.4/28.3 %) and Asian (11.6/15.7 %) origin. When the study population was restricted to the 14,636 travellers of German origin, 7.1 % of the returned travellers (4.6/9.6 %) were diagnosed with anaemia. The prevalence was significantly elevated among patients who travelled for >30 days (5.7 of males/10.6 % of females) and for male travellers visiting friends and relatives (7.7 %). However, these correlations were confounded by malaria. The prevalence of anaemia was significantly elevated only among returned travellers diagnosed with malaria (36.1 of males/26.9 % of females) and with symptomatic intestinal Entamoeba histolytica infections (30.0/33.3 %). CONCLUSION: Following the exclusion of confounding by malaria from the statistical analysis, the prevalence of anaemia was found to be significantly elevated among patients of African and Asian origin, and among patients of German origin who had travelled for >30 days, it could be mainly attributable to chronic, long-lasting causes. Although more than 550 travel-associated IDs were assessed in our study, only symptomatic intestinal Entamoeba histolytica infections and, to an even larger extent, malaria were determined to be of epidemiological significance for inducing anaemia among travellers.

Comparative study on infection-induced thrombocytopenia among returned travellers.

BACKGROUND: Thrombocytopenia is a frequent finding among ill returned travellers and may be caused by a large number of different conditions, including infectious diseases specific or typical for tropical and subtropical regions. In order to assess the diagnostic significance of thrombocytopenia we investigated a large cohort of returned travellers. METHODS: This was a comparative study in which data collected on 19,473 returned travellers who consulted the outpatient travel clinic of the the University of Munich Hospital between 1999 and 2009 were analysed. Of these, 732 (3.8%) travellers were diagnosed with thrombocytopenia, and their data were compared with those of the remaining 18,741 travellers with normal platelet counts. RESULTS: Thrombocytopenia was significantly more frequent among patients with malaria (63%), acute human immunodeficiency virus infection (48%), dengue fever/dengue haemorrhagic fever (DF/DHF; 47%), Epstein-Barr virus infectious mononucleosis (23%), paratyphoid/typhoid fever (14%), and rickettsiosis (12%). Malaria and DF/DHF caused 25% of all cases of thrombocytopenia (platelet count <140,000/µl) and 75% of all cases of severe thrombocytopenia (platelet count <30,000/µl). Sex, age, country of origin, duration and type of travel were not significantly correlated with thrombocytopenia. The most frequent travel destinations were Asia (42%), Africa (33%), and Latin America (14%). Travellers to Sub-Saharan Africa (high risk for malaria) and to South/South-east Asia (high risk for DF/DHF) had the highest relative risk for thrombocytopenia. CONCLUSION: Platelet count among returned travellers is an essential screening parameter, as thrombocytopenia is highly correlated with important infectious diseases, particularly with malaria and DF/DHF.

Skin disorders among travellers returning from tropical and non-tropical countries consulting a travel medicine clinic.

OBJECTIVE: To evaluate the causes and risks for imported skin disorders among travellers. METHODS: Data of 34,162 travellers returning from tropical and non-tropical countries and presenting at the outpatient travel medicine clinic of the University of Munich, Germany, between 1999 and 2009 were analyzed for this study. Of these, 12.2% were diagnosed with skin disorders. RESULTS: Main destinations visited were Asia (40%), Africa (27%) and Latin America (21%). Tourism in the form of adventure travel/backpacking (47%) and package holidays (23%) was the most common purpose of travel. The leading causes of skin disorders were arthropodal (23%), bacterial (22%), helminthic (11%), protozoan (6%), viral (6%), allergic (5%) and fungal (4%). The 10 most frequently diagnosed specific skin diseases associated with specific destinations were insect bites (17%, Southern Europe), cutaneous larva migrans (8%, Asia and Latin America), cutaneous leishmaniasis (2.4%, Mediterranean Region/Middle East), dengue fever (1.5%, Asia), rickettsioses (1.3%, Southern Africa), myiasis (0.8%, Central America), filarioses (0.7%, Africa), tick bites (0.6%, Central/Eastern Europe), schistosomiasis (0.6%, Africa) and tungiasis (0.6%, Africa). Travellers in sub-Saharan Africa had the highest relative risk of acquiring skin disorders. CONCLUSION: As more than 20% of all skin disorders among returned travellers were caused by arthropods and about 50% by infectious pathogens, pre-travel consultations should include specific prophylaxis and consider the most important risk factor for the travel destination.

Prophylactic immunisation against traveller's diarrhoea caused by enterotoxin-forming strains of Escherichia coli and against cholera: does it make sense and for whom?

Traveller's diarrhoea (TD) constitutes the most common disease relevant to travel medicine with ETEC as the leading causative pathogen. Cholera is the most serious, but very rare form of TD. ETEC and cholera share pathogenic mechanisms by producing a toxin that has an 80% amino acid homology. A consensus of German-speaking experts sees the indication to use the whole cell/B subunit oral cholera vaccine (WC--BS) if cholera is a risk for aid workers or travellers with an anticipated threat of cholera who stay under poor hygienic conditions. The use of the vaccine should be considered in the indication to avoid ETEC TD for travellers with predisposing illness or medication or for travellers at risk to develop a serious course.

Prevalence of infection with dengue virus among international travelers.

BACKGROUND: Dengue has been recognized as a potential hazard to tourists. A prospective, controlled study in the outpatient clinic of a German infectious disease clinic was conducted to assess the prevalence of dengue virus infection among international travelers. METHODS: Serum samples from 130 patients with signs or recent history clinically compatible with dengue (fever, headache, muscle and joint pain, or rash), 95 matched controls with diarrhea, and 26 patients who never visited a country endemic for dengue were investigated. RESULTS: Nine (6.9%) of the 130 patients with compatible symptoms and 1 (1%) of the 95 controls with diarrhea developed rising antibody titers against dengue virus. Of these 10 patients with probable dengue infection, 6 had been to Thailand, 2 to Malaysia, and 1 each to Indonesia and Brazil. CONCLUSIONS: Infection with dengue virus appears to be a realistic threat to travelers to Southeast Asia. Symptoms commonly associated with dengue, such as fever, myalgia, arthralgia, and vomiting, can be helpful for diagnosis when present, but the absence of typical symptoms does not exclude infection.

Diagnostic significance of blood eosinophilia in returning travelers.

This study was conducted to investigate the predictive value of blood eosinophilia (total white blood cell count with > or =8% eosinophils) for the diagnosis of travel-related infections in 14,298 patients who returned from developing countries. The data show that blood eosinophilia in travelers returning from developing countries has only limited predictive value for the presence of travel-related infections. However, the likelihood of the presence of helminth infections increases considerably with the extent of eosinophilia.

Long-term efficacy of primaquine in the treatment of vivax malaria in nonimmune travelers.

Fifty-six travelers presenting with vivax malaria to a German travel clinic were followed regularly for at least 18 months between 1984 and 1992 to investigate the long-term efficacy of primaquine in nonimmune patients without reinfection. All received a standard treatment of 15 mg of primaquine a day for 14 days following an initial total dose of 1,500 mg of chloroquine (base) given over a 48-hr period. None of the patients visited countries endemic for malaria during the period of observation. In seven patients (12.5%), relapses were confirmed microscopically by detection of malaria parasites in blood films. The frequency of relapses varied between one and four per patient and these occurred between 60 and 252 days after treatment. Four of these seven patients had acquired infection in Papua New Guinea or eastern Indonesia, while only five (10.2%) of the remaining 49 patients without relapses had traveled to these areas prior to referral (P < 0.01).

Assessing the incidence of infection with Plasmodium falciparum among international travelers.

Circumsporozoite (CS) antibodies, indicating plasmodial infection but not necessarily development of disease, have been shown to be reliable indicators of transmission in endemic areas. To estimate the actual rate of plasmodial infection, the prevalence of CS antibodies was investigated by an ELISA test system in a selected population of 2,131 travelers returning from areas endemic for malaria who presented to an outpatient clinic without any apparent symptom or clinical sign of malaria. Serum specimens from 104 of the investigated 2,131 patients (4.9%) were found to be positive (titer > or = 6.25 international ELISA units [IEU]). The geometric mean titer of antibody concentrations (IEU) in seropositive patients was 18.64 IEU (95% confidence interval [CI] = 13.15-24.13), while it was 2.1 IEU (95% CI = 1.8-2.4) in seronegative patients. A significantly above average risk for plasmodial infection could be found among travelers to East Africa (risk ratio [RR] = 4.5, P < 0.001), West Africa (RR = 4.5, P < 0.001), and Southern Africa (RR = 3.2, P = 0.015), while areas with a comparatively low risk included Central America (RR = 0.86, P < 0.001), the Indian subcontinent (RR = 0.45, P = 0.015), South America (RR = 0.49, P = 0.091), East Asia (RR = 0.68, P = 0.441), West Asia (RR = 0.24, P = 0.099), and Southeast Asia (RR = 0.69, P = 0.094). The results of this study emphasize the importance of adequate malaria chemoprophylaxis in nonimmune travelers to endemic areas. By use of the described method, estimates of the true infection rate of malaria in travelers can be derived for certain areas and the value of prophylactic measures can be demonstrated.

Japanese encephalitis vaccine in travellers. Is wider use prudent?

Vaccination against Japanese encephalitis has been carried out extensively in many Asian countries for the past 20 years and is also increasingly recommended for travellers to endemic areas. Although the currently available vaccine, manufactured from mouse brain, is generally considered to be highly effective and of low reactogenicity, approximately 50% of vaccinees report experiencing usually mild adverse effects following vaccination. Concern has been raised regarding potential neurological adverse effects but the incidence of such effects appears to be very low (around 1 to 2.3 per 1000000 vaccinations). Routine vaccination of all travellers to endemic areas is clearly not beneficial at this moment and use of the vaccine should remain restricted to persons spending a month or longer in endemic areas, especially rural areas, during the transmission season. However, when counselling individual travellers, it has to be kept in mind that the possibility of Japanese encephalitis can never be ruled out completely when travelling to endemic areas, and that such an infection can prove disastrous for the individual concerned.

Prophylaxis failure due to probable mefloquine resistant P falciparum from Tanzania.

Failures of mefloquine prophylaxis in travellers returning from Africa have been reported repeatedly. Non-compliance to chemoprophylaxis is considered to be a major factor for failure. Only few reports on mefloquine prophylaxis failure in sub-Saharan Africa were able to report blood levels of the drug that were sufficient for prophylactic effectiveness. We report the case of a 44-year-old German female who travelled to Tanzania for 3 weeks. The patient reported that she never missed a dose of mefloquine during her weekly prophylaxis schedule. Four weeks after returning from Tanzania, the patient presented with fever, headache and myalgia. Only a few trophozoites of Plasmodium falciparum were found in a thick film. Blood levels of mefloquine at that stage were at 1400 ng/ml, thus largely excluding non-compliance and malabsorption. To our knowledge, this is the first case of confirmed prophylaxis failure due to mefloquine resistance in East Africa.

Risk factors of chloroquine resistance in Plasmodium falciparum malaria.

OBJECTIVE: To identify patient-related risk factors of chloroquine resistance. DESIGN: A case control study. SUBJECTS: Plasmodium falciparum infected school children were followed prospectively for 7 days for the detection of chloroquine resistance. Cases were 38 individuals with chloroquine resistant infections. Controls were 125 individuals with chloroquine sensitive infections. Cases were compared with controls with respect to previous or current study factor levels. Subjects were recruited from randomly selected schools which were stratified for area. Study location was in North Guadalcanal, Solomon Islands. OUTCOME MEASURE: Treatment failure of chloroquine in standard dosage (25 mg/kg). Follow-up period was 7 days. RESULTS: Logistic regression resulted in 5 independent significant predictors of chloroquine resistance, obtained simultaneously with the diagnosis of malarial infection: (i) Young age (odds ratio (OR) for age < 7 years: 7.1; 95% confidence interval (CI): 2.5-25.0; OR per year increase after the age of 5 years: 0.8; 95% CI: 0.6-0.9). (ii) High parasite density (OR for > 1000/microliters: 5.0; 95% CI: 2.0-10.6; OR per 500 parasites/microliters increase: 1.3; 95% CI: 1.1-1.7). (iii) Normal spleen size (OR: 4.0, 95% CI; 1.5-10.8). (iv) Malnutrition (OR: 4.9; 95% CI: 1.8-13.2). (v) Presence of gametocytes in the thick smear (OR: 3.0; 95% CI: 1.1-8.0). CONCLUSION: The identified risk factors are easily measurable without special equipment. They may be useful for health workers in the Solomon Islands, even in remote areas, to identify Plasmodium falciparum infected individuals at high risk for chloroquine resistance before a treatment decision is made.

Adverse reactions to Japanese encephalitis vaccine in travellers.

Vaccination against Japanese Encephalitis (JE) has been carried out extensively in many Asian countries for the past 20 years. The vaccine was generally considered to be effective and of low reactogenity. However, since 1989 an unusual number of systemic reactions characterized mainly by generalized urticaria and/or angioedema following JE vaccination were reported from Australia, Canada and Denmark, 860 travellers were recruited during a period of 16 months for a prospective study with the aim to investigate the type and incidence of side effects following JE vaccination (JEV) in German travellers. 826 received a primary immunization (2 injections at days 0 and 7-14) and 34 received a single booster injection. A detailed standardized questionnaire was distributed to all vaccinees after the first injection. A total of 509 questionnaires could be evaluated, which represents a return rate of 59.2%. 46% of the vaccinees reported about no adverse events at all. 54% reported about one or more adverse effects. Local reactions at the injection site were observed by 209 vaccinees, while 65 reported about systemic side effects like headache, fever, dizziness and generalized rash. There was no significant difference following first or second injection of the primary immunization or the booster injection, respectively, regarding incidence, severity or type of side effects. 2.2% of the vaccinees reporting reactions sought medical advice and 1.8% were judged unfit for work for an average of 2.2 days. The amount of systemic reactions might indicate a potential hazard of serious anaphylactic reactions. Unlike hepatitis A. Japanese encephalitis is an extremely rare disease in travellers. Therefore, the risk of acquiring the disease when travelling to affected areas without prior immunization should be considered against the risk of developing serious side effects after vaccination. We conclude that JEV should remain restricted to travellers with an increased risk of acquiring JE.

The role of Blastocystis hominis as a possible intestinal pathogen in travellers.

The role of Blastocystis hominis as a pathogen for man has been controversially discussed, while travel history has been implicated as a risk factor of infection. Few controlled studies of the association between B. hominis and symptomatic diseases have been performed. Therefore, a case-control study among 795 German tourists returning from tropical countries was conducted. The prevalence of the organism among patients with and without symptoms was assessed. Blastocystis hominis was detected in 69 of 469 (14.7%) patients with diarrhoea and in 21 of 326 (5.7%) controls. However, other organisms causing diarrhoea were detected in 18 of the 69 (26.1%) symptomatic patients with B. hominis. Thus, 51 of 469 (10.8%) symptomatic patients had B. hominis in the absence of other pathogens in their stool, significantly more than in the asymptomatic group (5.2%; P = 0.005). Irrespective of the development of symptoms, the organism was most frequently acquired during journeys to the Indian subcontinent. The results of this study suggest that B. hominis is associated with development of diarrhoea in travellers to tropical destinations and that frequently concurrent infections with other organisms occur.

Use of dipstick tests for the rapid diagnosis of malaria in nonimmune travelers.

BACKGROUND: Swift diagnosis of falciparum malaria in nonendemic areas is frequently complicated by lack of experience on the side of involved laboratory personnel. Diagnostic tools based on the dipstick principle for the detection of plasmodial histidine-rich protein 2 (HRP-2) (ICT Malaria P.f. (R)) and parasite-specific lactate-dehydrogenase (pLDH) (OptiMal(R)), respectively, have become available for the qualitative detection of falciparum malaria. METHODS: In order to evaluate currently available assays, a series of studies was conducted: sensitivity and specificity were evaluated by investigation of specimens from 231 febrile returnees from endemic areas, cross reactivity in patients with rheumatoid factor (RF) was assessed among 92 patients from a rheumatology unit, and the quality of dipstick self-use by febrile travelers was tested in Kenya. RESULTS: Whereas the test kit based on the detection of HRP-2 performed with a sensitivity of 92.5% and a specificity of 98.3%, the kit for the detection of pLDH showed a sensitivity of 88.5% and a specificity of 99.4%. Cross-reactions with sera positive for rheumatoid factor occurred in 6.6% with the ICT Malaria P.f.(R), and in 3.3% with the OptiMal(R) test. Only ICT Malaria P.f.(R) was tested for quality of self-use among travelers. This dipstick assay was performed successfully by 67 patients (68.4%), but 31 (31.6%) were unable to obtain a result. CONCLUSION: Dipstick tests have the potential of enhancing speed and accuracy of the diagnosis of falciparum malaria, especially if nonspecialized laboratories are involved. However, microscopical testing remains mandatory in every single patient with the possible diagnosis of malaria. Self-use of dipstick tests for malaria diagnosis by travelers should only be recommended after appropriate instruction and training, including a successful performance of the test procedure.

[Epidemiology and clinical aspects of imported schistosomiasis]. / Epidemiologie und Klinik der importierten Schistosomiasis.

PATIENTS AND METHODS: Travel and medical histories as well as clinical features of 62 German and 21 native patients with schistosomiasis who were presented to a German outpatient clinic for infectious and tropical diseases were investigated in order to identify the risk factor leading to infection in travellers and expatriates. RESULTS: All patients were able to remember the incidents which led to a likely exposure to cercariae of schistosoma spp. Fifty-nine German patients (95%) acquired infection in Africa, 2 (3%) in South America and one each (2% each) in the Euphrat and the Mekong River, respectively. All but 1 native patients acquired infection in Africa. The highest proportion of infection (45% in Germans and 37% in native patients) was imported from West Africa. Patients returning from this area had had either contact with tributaries of the Niger or with waters of the Volta River, notably the Lake Volta and/or its delta. The most sensitive method for detection of schistosomiasis appeared to be a combination of thorough travel history and serological testing (IHA, IFAT and ELISA) of all patients with possible infection. CONCLUSIONS: In the investigated group, most infections were acquired by travellers on a lengthy and adventurous journey or by expatriates venturing outside their normal areas of activity. Most patients knew that they travelled in an area endemic for schistosomiasis but were uninformed about the risks they took with their behaviour in a specific setting. Others simply could not avoid skin exposure to freshwater like backpacking tourists travelling in boats on the Niger or Congo River and native patients. Travellers to the tropics should therefore be informed thoroughly about the dangers of water-related diseases such as schistosomiasis.

[Malaria--rapid diagnostic tests and emergency self-medication]. / Malaria-Schnelltests und Notfall-Selbsttherapie.

WHO recommendations have adopted the option of stand-by emergency treatment (SBT) for travellers to areas where malaria is endemic and medical attention may not be obtained within 24 hours after onset of symptoms. Indication and choice of drugs for SBT depend on use and kind of a chemoprophylactic regimen, situation of plasmodial resistance at the destination, and contraindications and tolerability in the individual traveller. However, the diagnosis of malaria on clinical grounds alone is unreliable, and fever occurs frequently during travel to malaria endemic areas from various reasons. The possibility of malaria has to be considered in all cases of unexplained fever that starts after the 7th day of stay in an endemic area. Studies in European travellers have shown that only 0.5-1.4% of all travellers to whom SBT medication has been prescribed, will finally use it. SBT use in febrile travellers (8.1-10.4% of all travellers) has been 4.9-17%, but plasmodial infection could be confirmed retrospectively in 10.8-16.7% of SBT-users only. The recent introduction of rapid diagnostic tests (RDT) for malaria has provided a potential tool to self-diagnose and treat a possible malaria attack when medical attention or microscopic diagnosis is not available. However, the utilisation of currently available RTDs by travellers has been shown to be technically problematic. Healthy volunteers were able to learn how to perform the tests, especially when standard written instructions were supplemented with verbal information (75 vs. 90% successful performance). But their interpretation of test results was unsatisfactory, with a high rate of false-negatives (14.1%). In another study in febrile European tourists in Kenya, only 68% of patients were able to perform the RDTs correctly, and 10 out of 11 with microscopically confirmed malaria failed to diagnose themselves accurately. Thus, besides appropriate training before departure, technical improvements are required before such RDT kits can be recommended for self-use by travellers.

[Sequelae of imported tropical diseases in Germany]. / Folgen importierter Tropenkrankheiten in Deutschland.

20-50% of all travellers to tropical and subtropical countries experience health problems during or after travel. Mainly respiratory tract infections or gastrointestinal disorders are predominant. As specific disorders imported from the tropics traveller's diarrhoea is prevailing, however amebic and helminthic infections, hepatitis A, malaria, sexually transmitted diseases as well skin disorders are rather common. Classical tropical diseases such as cholera, sleeping sickness or trachoma play only a very minor role as imported infections. The majority of health impairments during or after travel are uncomplicated or self limiting. However, falciparum malaria, viral hepatitides, typhoid fever, tropical viral infections and infections of the CNS can take a malicious course. Early diagnosis and treatment generally can provide complete cure without sequels. Sequels are most commonly seen following hepatitis B and C as well as HIV infection but also as a result of CNS infections (e.g. encephalitis) and of imported tuberculosis. For medical expert opinion it is essential that sequels were present already during the acute phase of illness. The socio-economical impact of infections imported from the tropics is considerable due to the high morbidity figures. Preventive measures before and after a stay in tropical countries could markedly reduce the health risks involved.

[Typhus abdominalis in travelers. Headaches originating in the abdomen]. / Typhus abdominalis bei Reisenden. Kopfschmerzen aus dem Bauch heraus.

The incidence of typhoid fever in emerging countries remains high, being estimated to be 500 per 100,000 head of population. Tourists from the industrialized countries can contract the infection in particular when travelling under conditions of poor hygiene in endemic regions. The risk of contracting typhoid appears to be highest on lengthy travels on the Indian subcontinent, while short visits to Latin America or Africa appreciably less often result in an infection. Currently, two vaccines are approved for use in Germany: a live oral vaccine containing the defective S. typhi mutant Ty 21a, and a parenteral inactivated vaccine prepared from the Vi capsid antigen of S. typhi. Both vaccines are well tolerated and provide similar levels of protection. The reported protection rate for the live vaccine varies in various studies between 33 and 67%; that of the inactivated vaccine between 55 and 75%. Medical advice prior to travel should weigh up such risk factors as age, duration of the journey, destination and the nature of the journey. While vaccination is particularly recommended for travelers with one or more risk factors, it should always be pointed out that an infection is nevertheless possible. In view of the fact that immunization against hepatitis A and typhoid fever are often indicated simultaneously, the development of a combination vaccine would be desirable.

[The risk of contracting hepatitis A or hepatitis B run by visitors to the Mediterranean and Eastern Europe]. / Infektionsrisiko für Reisende im Mittelmeerraum und in Osteuropa. Hepatitis A und B: Souvenirs, die keiner haben will.

Hepatitis A and B continue to represent a risk for travelers. Those traveling to tropical countries are usually aware of this risk, while those visiting a Mediterranean country often are not. This investigation presents a destination-related risk assessment and vaccination recommendations for travellers, on the basis of incidences and prevalences of hepatitis A and hepatitis B. For hepatitis B, the WHO classification based on HBsAg prevalence has been selected. For hepatitis A, countries have been categorized as low-, moderate- or high-risk. A comparison of infection risk with the numbers of airline passengers showed that in particular the large number of travelers to Tunisia, Turkey and Egypt, in conjunction with hygienic conditions in those countries, represent a source of imported hepatitis A. With regard to destinations in the Mediterranean and Eastern Europe, too, the risk of contracting hepatitis A or hepatitis B is not always negligible, so that vaccination may need to be recommended.

[Travelers' diarrhea]. / Reisediarrhoe.

Travelers diarrhea affects millions of tourists each year. Most cases are caused by a variety of bacterial enteropathogens: toxigenic Escherichia coli, Campylobacter, Shigella, Salmonella, Aeromonas, Plesiomonas and non-cholera vibrios. Treatment may include antibacterial therapy with either ciprofloxacin, or azitrhomycin, or rifaximin. Viral pathogens such as norovirus usually cause short-term illness that typically resolves before travelers seek medical attention. Chronic gastrointestinal disease in returning travelers often is caused by parasitic pathogens like Giardia lamblia. The impact of prevention of travelers diarrhea is limited, therefore travelers should be informed about early self-treatment.