Diarrhoea in a large prospective cohort of European travellers to resource-limited destinations

Background: Incidence rates of travellers' diarrhoea (TD) need to be updated and risk factors are insufficiently known. Methods: Between July 2006 and January 2008 adult customers of our Centre for Travel Health travelling to a resource-limited country for the duration of 1 to 8 weeks were invited to participate in a prospective cohort study. They received one questionnaire pre-travel and a second one immediately post-travel. First two-week incidence rates were calculated for TD episodes and a risk assessment was made including demographic and travel-related variables, medical history and behavioural factors. Results: Among the 3100 persons recruited, 2800 could be investigated, resulting in a participation rate of 89.2%. The first two-weeks incidence for classic TD was 26.2% (95% CI 24.5-27.8). The highest rates were found for Central Africa (29.6%, 95% CI 12.4-46.8), the Indian subcontinent (26.3%, 95% CI 2.3-30.2) and West Africa (21.5%, 95% CI 14.9-28.1). Median TD duration was 2 days (range 1-90). The majority treated TD with loperamide (57.6%), while a small proportion used probiotics (23.0%) and antibiotics (6.8%). Multiple logistic regression analysis on any TD to determine risk factors showed that a resolved diarrhoeal episode experienced in the 4 months pre-travel (OR 2.03, 95% CI 1.59-2.54), antidepressive comedication (OR 2.11, 95% CI 1.17-3.80), allergic asthma (OR 1.67, 95% CI 1.10-2.54), and reporting TD-independent fever (OR 6.56, 95% CI 3.06-14.04) were the most prominent risk factors of TD. Conclusions: TD remains a frequent travel disease, but there is a decreasing trend in the incidence rate. Patients with a history of allergic asthma, pre-travel diarrhoea, or of TD-independent fever were more likely to develop TD while abroad.