Benznidazole is one of the two most effective antiparasitic drugs for Chagas’ disease treatment. However, knowledge about its toxicity profile is mostly based on post-marketing observational studies. Our study combines data from two prospective clinical trials designed to assess the safety of the drug newly produced by ELEA Laboratories (Abarax^®). Eligible participants were selected using a consecutive sampling strategy in the CINEBENZ and BIOMARCHA studies between 2013 and 2016 (EUDRACT 2011-002900-34 and 2012-002645-38, respectively, and clinicaltrials.gov NCT01755403 and NCT01755377, respectively). Enrolled subjects received treatment with 5 mg/kg/day benznidazole orally in two divided doses for 8 weeks and were followed up fortnightly. We observed 305 adverse reactions in 85 of 99 participants (85.9%). Each patient had a median of three adverse reactions, 89.5% were mild and the median duration was 12 days. Most adverse reactions appeared in the first month of treatment except arthritis and peripheral neuropathy. Twenty-six patients did not complete treatment: 2 were withdrawn, 1 for ectopic pregnancy and 1 for epilepsy relapse due to cysticercosis; 2 were lost to follow-up; and 22 were owing to adverse reactions, two of them severe. We observed some unexpected adverse reactions that have not been described previously, such as psychiatric symptoms, erectile dysfunction, menstrual cycle alterations and lung infiltration. There is a very high frequency of adverse reactions to benznidazole. Most adverse reactions are mild, but the treatment burden is significant and unexpected reactions are not rare. Severe reactions are uncommon, but they can be life-threatening. Further studies are necessary to optimize treatment.

We describe the epidemiological pattern and genetic characteristics of 242 acute dengue infections imported to Europe by returning travellers from 2012 to 2014. The overall geographical pattern of imported dengue (South-east Asia > Americas > western Pacific region > Africa) remained stable compared with 1999 to 2010. We isolated the majority of dengue virus genotypes and epidemic lineages causing outbreaks and epidemics in Asia, America and Africa during the study period. Travellers acted as sentinels for four unusual dengue outbreaks (Madeira, 2012–13; Luanda, 2013; Dar es Salaam, 2014; Tokyo, 2014). We were able to characterise dengue viruses imported from regions where currently no virological surveillance data are available. Up to 36% of travellers infected with dengue while travelling returned during the acute phase of the infection (up to 7 days after symptom onset) or became symptomatic after returning to Europe, and 58% of the patients with acute dengue infection were viraemic when seeking medical care. Epidemiological and virological data from dengue-infected international travellers can add an important layer to global surveillance efforts. A considerable number of dengue-infected travellers are viraemic after arrival back home, which poses a risk for dengue introduction and autochthonous transmission in European regions where suitable mosquito vectors are prevalent.

Ten cases of chikungunya were diagnosed in Spanish travellers returning from Haiti (n=2), the Dominican Republic (n=7) or from both countries (n=1) between April and June 2014. These cases remind clinicians to consider chikungunya in European travellers presenting with febrile illness and arthralgia, who are returning from the Caribbean region and Central America, particularly from Haiti and the Dominican Republic. The presence of Aedes albopictus together with viraemic patients could potentially lead to autochthonous transmission of chikungunya virus in southern Europe.