In 2017, 3,391 cases of acute hepatitis A were reported, including 3,320 in mainland France. The annual case rate for acute hepatitis A for all of France was 5.1 per 100,000 inhabitants (Figure 1). This sharp increase (a rate five times higher than in 2016) is linked to the epidemic that began in late 2016, continued into 2018, and particularly affected men who have sex with men (MSM).

Due to this epidemic, there was a significant disparity in reported rates in 2017 between men (8.2/100,000) and women (2.1/100,000), as well as across age groups. The highest reported rate was 16.3 per 100,000 among men aged 26 to 45 (Figure 3). Children aged 15 or younger, who are usually the most affected by acute hepatitis A, had, along with those over 45, the lowest reported rate in 2017 (2.9/100,000).

Geographically, the highest reported rate was 17.3 per 100,000 in the Paris department, and high rates were observed in the departments of the largest metropolitan areas in mainland France in 2017. While in 2016, reporting rates by department ranged from 0 to 3.5 per 100,000, in 2017, 27 departments had a reporting rate of 5 per 100,000 or higher, and 6 departments had a reporting rate of 10 per 100,000 or higher (Map).

The main risk exposures in the 2 to 6 weeks prior to the onset of symptoms were the presence of hepatitis A cases among close contacts (32% of cases), including 54% of cases within the family, consumption of seafood (27% of cases), and a stay outside mainland France (27% of cases) (Figures 4 and 5). Among cases who had traveled outside mainland France, the distribution of countries visited also differed from that of previous years, with 29% of cases having traveled to a Maghreb country (51% in 2016) and 41% having traveled to a European country (9% in 2016).

Data on sexual practices are not collected as part of the mandatory reporting of acute hepatitis A cases. During the 2017 outbreak, a body of evidence indicated that the affected population consisted primarily of MSM, including a significant shift in the sex ratio (Figure 2), investigations of clustered cases involving individuals from MSM communities, viral strain sequencing, and the observation of similar phenomena in various European countries.

The epidemiology of acute hepatitis A in France in 2017 continues to justify the application of vaccination recommendations advocating vaccination for MSM, as well as for family members of a confirmed case and during travel to an endemic area (2018 Vaccination Schedule and Health Recommendations for Travelers, 2018).

Finally, in 2017, 11% of reported cases were part of a cluster investigated by the Regional Health Agencies (ARS) and the regional Public Health France Intervention Units (Cire).

Number of cases and annual case-reporting rate per 100,000 inhabitants, acute hepatitis A, all of France, 2006–2017 (Figure 1)

Male-to-female sex ratio of reported cases of acute hepatitis A, France, 2016–2017 (Figure 2)

Estimated incidence of acute hepatitis A by age group and sex, France, 2017 (Figure 3)

Number of reported cases of acute hepatitis A by month of diagnosis and by history of travel outside metropolitan France, metropolitan France, 2017 (Figure 4)

Characteristics and risk exposures of reported cases of acute hepatitis A by age group, France, 2017 (table)

¹ Percentages calculated for reported cases, ² asthenia, anorexia, fever,

Reported incidence of acute hepatitis A by department, France, 2017 (map)