Hepatitis A Outbreak in France and Europe - Update as of June 20, 2017

Published on 23 June 2017

Hepatitis A Outbreak in France and Europe - Update as of June 20, 2017

Since February 2017, several countries in Europe have observed a significant increase in the number of hepatitis A cases, particularly affecting men who have sex with men (MSM); three "epidemic" strains of the hepatitis A virus are primarily responsible for this. Cases linked to this outbreak have been reported in Austria, Belgium, Denmark, Finland, France, Ireland, Italy, the Netherlands, Norway, Portugal, Slovenia, Spain, Sweden, and the United Kingdom. Spain and Italy are the hardest hit, with high numbers of cases among men.

The situation in France

Hepatitis A is monitored in France through mandatory reporting and by the National Reference Center.

Epidemiological data

From January 1 to May 31, 2017, 771 cases of acute hepatitis A were reported: 65 in January, 87 in February, 155 in March, 185 in April, and 279 in May. The number of acute hepatitis A cases reported during the first 5 months of 2017 is already higher than 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 (Figure 1).

Sexual orientation is not included in the information collected as part of 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 reported cases and none of the classic risk factors are present (other cases or children in the social circle, work in a high-risk setting, travel outside mainland France, or consumption of seafood), or when sexual orientation is documented during investigations. The analysis of the male-to-female sex ratio 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 increase in the male-to-female sex ratio observed here (4 in 2017 vs. 1 in 2016) and the results of initial investigations into clusters of cases strongly suggest that the MSM population is the most affected by this epidemic, in France as in other European countries.

By region, this 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) (Map). Starting in January 2017, the male-to-female ratio among the 599 cases aged 18 to 55 has been increasing (Figure 2), though at varying rates. To date, it is highest (between 10 and 11) in the Hauts-de-France, Île-de-France, and Provence-Alpes-Côte d'Azur regions.

Virological data

Between late 2016 and June 9, 2017, the CNR identified the presence in mainland France of three European “epidemic” strains circulating among MSM in many European countries. These strains are:

RIVM-HAV16090, known as "Nl Europride,"
VRD-521-2016, known as "UK travel to Spain,"
V16-25801, known as “Germany Munich/Berlin/Frankfurt.”

During this period, the CNR identified 294 samples containing one of these three strains; 276 (94%) of these samples were from men, with an average age of 36. The CNR’s genotyping results were as follows: 173 (59%) of the strains were of the VRD-521-2016 type, 113 (38%) of the RIVM-HAV16090 type, and 8 (3%) of the V16-25801 type.

In conclusion, the hepatitis A outbreak among men aged 18 to 55 now affects all metropolitan regions, albeit at varying levels, with a clear upward trend in the number of cases. Transmission among MSM contributes significantly to this increase.