Travel-associated infection presenting in Europe (2008-12): an analysis of EuroTravNet longitudinal, surveillance data, and evaluation of the effect of the pre-travel consultation

Abstract

Background: Travel is important in the acquisition and dissemination of infection. We aimed to assess European surveillance data for travel-related illness to profile imported infections, track trends, identify risk groups, and assess the usefulness of pre-travel advice.

Methods: We analysed travel-associated morbidity in ill travellers presenting at EuroTravNet sites during the 5-year period of 2008-12. We calculated proportionate morbidity per 1000 ill travellers and made comparisons over time and between subgroups. We did 5-year trend analyses (2008-12) by testing differences in proportions between subgroups using Pearson's χ(2) test. We assessed the effect of the pre-travel consultation on infection acquisition and outcome by use of proportionate morbidity ratios.

Findings: The top diagnoses in 32 136 patients, ranked by proportionate morbidity, were malaria and acute diarrhoea, both with high proportionate morbidity (>60). Dengue, giardiasis, and insect bites had high proportionate morbidity (>30) as well. 5-year analyses showed increases in vector borne infections with significant peaks in 2010; examples were increased Plasmodium falciparum malaria (χ(2)=37·57, p<0·001); increased dengue fever (χ(2)=135·9, p<0·001); and a widening geographic range of acquisition of chikungunya fever. The proportionate morbidity of dengue increased from 22 in 2008 to 36 in 2012. Five dengue cases acquired in Europe contributed to this increase. Dermatological diagnoses increased from 851 in 2008 to 1102 in 2012, especially insect bites and animal-related injuries. Respiratory infection trends were dominated by the influenza H1N1 pandemic in 2009. Illness acquired in Europe accounted for 1794 (6%) of all 32 136 cases-mainly, gastrointestinal (634) and respiratory (357) infections. Migration within Europe was associated with more serious infection such as hepatitis C, tuberculosis, hepatitis B, and HIV/AIDS. Pre-travel consultation was associated with significantly lower proportionate morbidity ratios for P falciparum malaria and also for acute hepatitis and HIV/AIDS.

Interpretation: The pattern of travel-related infections presenting in Europe is complex. Trend analyses can inform on emerging infection threats. Pre-travel consultation is associated with reduced malaria proportionate morbidity ratios and less severe illness. These findings support the importance and effectiveness of pre-travel advice on malaria prevention, but cast doubt on the effectiveness of current strategies to prevent travel-related diarrhoea.

Funding: European Centre for Disease Prevention and Control, University Hospital Institute Méditerranée Infection, US Centers for Disease Control and Prevention, and the International Society of Travel Medicine.