1) What is the attack rate of symptomatic and asymptomatic (tropical) diseases in long-term travelers. 2) Which behavioral risk factors are of influence on the attack rates? (compliance with preventive measures, other risk behaviouur)3) Are certain groups of long-term travellers at higher risk than others? (e.g., to certain destinations, expatriates, backpackers)4) Are attack rates for the infectious diseases under study different between long-term and short-term travellers?5) Is there a need for post-travel screening and if yes, for which infections?
Guidelines for travellers vaccinations, malaria prevention, and other health advices are based on a combination of theoretical risks, prevalence of symptomatic disease in returned travellers, and surveillance data of notifiable diseases. Available data are mostly on short-term travellers. Long-term travellers run higher risks because they are exposed over a longer period, but also other factors may differ and be of influence on risks, such as compliance with preventive measures and behavioural factors. Data on the attack rate of symptomatic and asymptomatic infections in long-term travellers are scarce and, if available, they are conducted in specific occupational groups (e.g., American Peace Corps Volunteers). This study will prospectively collect data of long-term travellers who travel 3-12 months: bloodsamples will be collected before departure and after return. To determine the attack rate of infections, they are tested for seroconversion for falciparum malaria, dengue fever, schistosomiasis, filariasis, strongyloidiasis, toxocariasis, hepatitis E, syphilis and hiv. With these data, attack rates for different (tropical) infectious diseases will be estimated, and compared to rates in short term travellers.Eosinophile counts are measured and evaluated for their use as predictive test for tropical infections.Also, epidemiological data will be collected and risk factors for disease will be determined in order to find out if certain groups of long-term travellers (e.g. backpackers, expatriates, those who comply less with prevention measures) are at higher risk than others.With the results of this study, the current guidelines will be evaluated and amended where necessary. |
