Listeriosis is a food-borne disease of public health importance that has recently been involved in prolonged outbreaks. Despite its relevance, listeriosis is under-reported in many European countries.

We aimed to describe listeriosis epidemiology in Spain from 1997–2015.

We performed a retrospective study using the Spanish hospitalisation database. We calculated the mean number of hospitalisations per year and region. Pregnancy and neonatal-related listeriosis rates were computed. Relation between death and the presence of underlying health conditions was explored.

Between 1997–2015, 5,696 listeriosis hospitalisations occurred, showing a constantly increasing trend. Higher hospitalisation rates were located in the north of the country compared to southern regions. The age group ≥ 65 years old was the most represented (50%). Pregnant women and newborns accounted for 7% and 4% of hospitalisations, respectively. An underlying immunocompromising condition was present in 56.4% of patients: cancer (22.8%), diabetes mellitus (16.6%) and chronic liver disease (13.1%). Death occurred in 17% of patients, more frequently among those ≥ 65 years old (67.5%), with sepsis (39.9%) or with meningoencephalitis (19.2%).

Listeriosis is an emergent public health problem in Spain that calls for targeted action. Further prevention strategies are urgently needed, including food safety education and messaging for all at-risk groups.

In an outbreak of hepatitis A among men who have sex with men (MSM) in Berlin (2016 and 2017), patients frequently reported anonymous sex and use of dating applications to meet sexual contacts, hampering tracing and vaccination of contacts.

Our objective was to evaluate dating apps and websites as a means of spreading prevention messages among MSM during the ongoing outbreak.

Advertisements in different formats were placed on three MSM dating apps and eight websites for anonymous dating during three weeks in March and April 2017. We calculated frequency of ads shown and click-through rates (CTR) and investigated the independent effect of format and platform on the number of clicks using a negative binomial regression model. We evaluated the campaign’s impact using a survey among visitors of a large gay-lesbian street-festival in Berlin.

Overall, 1,920,180 ads were shown and clicked on 8,831 times (CTR = 0.46%). The multivariable model showed significantly more clicks on one dating app (incidence rate ratio (IRR) = 9.5; 95% confidence interval (CI): 7.7–12.2) than on websites and on full-screen ads (IRR = 3.1; 95% CI: 2.5–3.8) than on banner ads. Of 266 MSM who participated in the survey, 190 (71%) knew about the outbreak and 39 (15%) declared to have been vaccinated recently because of the campaign.

Dating apps provided a means to rapidly reach and influence a substantial number of MSM in Berlin and should complement case-based contact tracing among MSM in outbreak settings. Clicking on ads depended on platform and format used.