Hepatitis A (HAV) is a viral infection causing a range of symptoms, sudden onset of fever, malaise, diarrhea, and jaundice. It is mostly transmitted fecal-oral through contaminated food, with immediate household and sexual contacts having a higher risk of infection. Since 2016 an increased number of HAV infections, mostly affecting men who have sex with men (MSM) have been noticed worldwide, with three main genotypes circulating. We report here on the first spillover outbreak of the MSM-associated HAV genotype RIVM-HAV16-090 in the German general population in November 2017-February 2018. In total, twelve cases could be attributed to the outbreak with the index case and a coworker in a butchers shop being the most probable source of the outbreak. The identical HAV genotype was detected in two environmental samples in the premises of the butchers shop and in nine cases. Outbreak control measures included detailed contact tracing and stool examinations, several environmental investigations, thorough cleaning, and disinfection of the premises of the butchers shop. Post-exposure vaccination was recommended to all unprotected contacts during the investigation. Furthermore, although hand-washing facilities were in accordance with the required law, additional installment of soap and disinfectant dispensers and contactless faucets has been recommended.
Keywords: Foodborne outbreak; Hepatitis A virus; MSM-cluster genotype.