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Hepatitis A: Rise in Cases Among Gay and Bisexual Men

Since February 2017, several countries in Europe (Austria, Belgium, Denmark, Spain, Finland, France, Ireland, Italy, the Netherlands, Norway, Portugal, Slovenia, Sweden, and the United Kingdom) have observed a significant increase in the number of hepatitis A cases, particularly affecting men who have sex with men (MSM).From January 1 to May 31, 2017, 771 cases of acute hepatitis A were reported through mandatory reporting (MR). This number of cases already exceeds the total number of cases reported in 2016 (693 cases). This outbreak primarily affects men, who account for 616 (79.9%) of the 771 cases reported in 2017. Sexual orientation is not included in the information collected under the mandatory reporting system. However, clusters of cases among MSM are suggested when an increase in the male-to-female sex ratio is observed among the reported cases and none of the classic risk factors are present (other cases or children in the household, work in a high-risk setting, travel outside mainland France, or consumption of seafood), or when sexual orientation is documented during investigations. The analysis presented below focused on cases aged 18 to 55 to exclude potential polyclonal reactions (a resurgence of hepatitis A-specific antibodies several years after a past infection), which are more common in those over 55.The observed increase in the male-to-female sex ratio (4 in 2017 vs. 1 in 2016) and the results of initial investigations into clustered cases strongly suggest that the MSM population is the most affected by this epidemic, in France as in other European countries.The hepatitis A outbreak among men aged 18 to 55 now affects all metropolitan regions, albeit to varying degrees. The increase in the number of cases is highest in Île-de-France (221), Hauts-de-France (157), followed by Auvergne-Rhône-Alpes (79), Provence-Alpes-Côte d’Azur (53), and Occitanie (50).As at the national level, the male-to-female ratio for reported cases among people aged 18 to 55 in Bourgogne-Franche-Comté in 2017 was 3:1. The complete regional update is available starting on page 4 of this week’s epidemiological report.The website sexosafe.fr, dedicated to HIV and sexually transmitted infection prevention for MSM, has been updated with a section on hepatitis A prevention. From June 23 to July 12, 2017, informational messages are being shared on Facebook and dating apps to raise awareness of the outbreak and remind users of preventive measures.