Hepatitis A Outbreak in France and Europe - Update as of November 13, 2017
Since February 2017, several European countries have seen a significant increase in the number of hepatitis A cases, particularly among 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 many European countries (Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, the Netherlands, Norway, Portugal, Slovenia, Spain, Sweden, and the United Kingdom).
The situation in France
Hepatitis A is monitored in France through mandatory reporting and by the National Reference Center (CNR for enterically transmitted hepatitis viruses).
Epidemiological data
From January 1 to October 31, 2017, 2,980 cases of hepatitis A were reported: 66 in January, 92 in February, 162 in March, 200 in April, 320 in May, 368 in June, 501 in July, 462 in August, 467 in September, and 342 in October. The number of hepatitis A cases reported during the first 10 months of 2017 is four times higher than the total number of cases reported in 2016 (697 cases).
This outbreak primarily affects men, who account for 2,355 (79%) of the 2,980 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 metropolitan 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, the most affected age group, to avoid accounting for 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 (3.8 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.
The most affected regions are Île-de-France (674), Hauts-de-France (466), followed by Auvergne-Rhône-Alpes (437), Provence-Alpes-Côte d'Azur (343), Occitanie (261), and Nouvelle-Aquitaine (198) (Map).
Starting in January 2017, the male-to-female sex ratio among the 2,308 cases aged 18 to 55 increased (to around 8), decreased between May and June, and then remained relatively stable (around 5) between July and October (Figure 2). By region, the sex ratio increased but to varying degrees. It is currently highest in the PACA (11) and Île-de-France (8) regions, followed by the Hauts-de-France and ARA regions at around 6, and finally around 5 for the Nouvelle-Aquitaine region.
Virological data
Between late 2016 and September 21, 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 885 samples containing one of these three strains; 776 (88%) of these samples were from men, with an average age of 36 years. The CNR’s genotyping results were as follows: 500 (56%) of the strains were of the VRD-521-2016 type, 362 (41%) of the RIVM-HAV16090 type, and 23 (3%) of the V16-25801 type.
In summary
The hepatitis A outbreak is currently affecting all metropolitan regions to varying degrees, with significant transmission among MSM. Overall, the number of hepatitis A cases has decreased since August 2017 among men and September among women, but the male-to-female ratio among those aged 18–55 remains high. It appears that the peak of the outbreak occurred in July, but the persistence of a high male-to-female ratio indicates that HAV continues to spread among men in the 18–55 age group.
Number of hepatitis A cases by sex, France 2016–2017
Male-to-female sex ratio of hepatitis A cases aged 18 to 55, France 2016–2017
Number of hepatitis A cases by region (men and women), January–October 2017, metropolitan France
How can you protect yourself against hepatitis A?
Prevention recommendations are available on the Santé publique France website:
Recommendations for men who have sex with men: http://www.sexosafe.fr/vaccination
To learn more about the epidemiological situation in the regions:
To learn more about the epidemiological situation of hepatitis A in Europe:
http://ecdc.europa.eu/en/healthtopics/hepatitis_A/
To learn more about the epidemiological situation of hepatitis A in France:
National Reference Center: http://www.cnrvha-vhe.org/
