Rhinitis was defined as nasal discharge or congestion. Cough could be dry GSK1120212 mouse or productive. Signs of skin infection included redness, swelling, tenderness, and/or pus-like drainage. Arthralgia was defined as inflammatory or non-inflammatory

joint pain. Abdominal pain could be acute or recurrent. An episode of a symptomatic infection was defined as an aforementioned symptom at one or more consecutive days. Data were collected before departure to gain information about baseline symptoms, and for 2 weeks after return to encompass incubation periods of the most (acute) travel-related infectious diseases. In the Results section, the term “travel-related” refers to the period of travel itself and the 2 weeks thereafter. According to 17-AAG clinical trial the Dutch national guidelines on travel advice, of the pairs included, only the immunocompromised travelers were prescribed ciprofloxacin (500 mg 2 times a day, for 5 days in case of ISA and for 3 days in case of IBD), to be used as immediate self-treatment after the first passage of loose or watery stools.7 Controls were advised to see a doctor in case of diarrhea with fever, blood in stools, or diarrhea persisting for 3 days or more.7 Power analysis showed that 70 pairs were needed to prove a diarrhea outcome ratio of 2 or more, with α = 0.05and power = 80%. This study was

approved by a medical ethics committee. All participants gave their informed consent. A random effects Poisson regression model was used to estimate incidence rates (IRs) and accompanying incidence rate ratios

(IRR). IR was defined as the number of symptom onsets divided by the sum of symptom-free days for all individuals during a specific time period. A random effects logistic regression model was used to estimate the number of symptomatic days and accompanying odds ratios (ORs). The number of symptomatic days reflects an individual’s probability to have a symptom on an arbitrary day. It was calculated to compare the disease burden between the immunocompromised travelers and their controls. The random effects model takes into account two levels of correlation: (1) immunocompromised selleck compound travelers and their travel companions had more or less the same exposure, and thus are not independent; (2) for IRs, there may be repeated episodes of a symptom within an individual; for numbers of symptomatic days, presence of symptoms over the days within an individual are correlated. ISA pairs and IBD pairs were analyzed separately. For estimation of the parameters, a Bayesian approach was used, starting with non-informative priors. Posterior distributions were obtained by Markov Chain Monte Carlo methods, using the WinBUGS program.16,17 Three chains were generated, based on different sets of starting values. Parameter estimates are the medians of the posterior distributions. The range from the 2.5% to the 97.5% quantile is used to quantify the uncertainty in the parameter estimates.