Hepatitis A outbreak in Barcelona among men who have sex with men (MSM), January-June 2017: A hospital perspective

Background & aims: Acute hepatitis A is transmitted mainly via the faecal-oral route and/or contaminated aliment. Furthermore, several outbreaks in the men who have sex with men (MSM) population classified hepatitis A as a sexually transmitted disease (STD). We aimed to clarify an ongoing hepatitis A outbreak in Barcelona with respect to patients' characteristics and viral phylogenetic analysis.

Methods: We prospectively analyzed 46 cases of hepatitis A infection that were registered in our hospital between January and June 2017. We evaluated demographics data, risk factors, presenting symptoms, sexual orientation, comorbidities and further STD infections. The phylogenetic correlation of the current circulating viruses among them and other hepatitis A strains was assessed by sequencing of the VP1/P2A region.

Results: Most patients were male (44, 96%) with median age 33.5 years (range 28-50). Thirty-one (67%) were MSM and 18 (39%) required hospitalization. Molecular phylogenetic analyses revealed that all patients were infected by hepatitis A subgenotype IA strains. Moreover, current strains comprised 3 distinct clusters, previously reported in ongoing outbreaks in the United Kingdom, Berlin and the Netherlands. However, these strains were phylogenetically diverse to those previously reported in Barcelona metropolitan region.

Conclusions: Ongoing hepatitis A outbreak in Barcelona affects primarily the MSM community and is phylogenetically linked to current hepatitis A outbreaks described in other European countries. As a result of the high admission rate, these outbreaks may impact the admission pattern of referral liver units. Control measures, for example vaccinations programs tailored to the MSM community, must be taken to control further spreading.