Hepatitis A 2017-2018

Hepatitis A 2017-2018

Statens Serum Institut (SSI) received 41 notifications in 2017 and 65 in 2018 of persons who had become infected with hepatitis A virus (HAV). Figure 1 presents the development in the number of notified HAV cases by infection in Denmark and abroad in the 2009-2018 period. The number of infected persons in Denmark was substantially higher in 2018 than in the preceding four years, and this was due to an increased number of disease outbreaks (see the separate section on this). The many patients observed in 2013 were due to a large outbreak caused by frozen strawberries.

This was previously described in EPI-NEWS 48/13 and 48/14.


The patients notified with HAV in 2017 and 2018 were from 1 to 90 years of age (median age 38 years), 59% were men (Figure 2).


Country of infection

The number of notified HAV cases by origin and place of infection is presented in Table 1. A total of 62 persons had become infected in Denmark (58%). The majority of these (85%) were of Danish origin. A total of 41 persons had become infected abroad. Sixteen persons of Danish origin were reported as having become infected abroad in Indonesia, Israel, North Macedonia, Morocco (2), Namibia, Pakistan (2), Poland, Spain (3), Great Britain, Turkey and Germany (2). Five second-generation immigrants became infected abroad in connection with family visits in the following countries: Morocco, Sudan, Afghanistan, Somalia and Pakistan. Nineteen persons born abroad had acquired HAV in 16 foreign countries.



Hepatitis A outbreak in dates

From January to March 2018, a total of 31 patients were registered as part of a Danish outbreak. A total of 18 females and 13 males aged 14-90 years were affected. The median age was 63 years.

A total of 18 patient samples were verified with genotype IIIA. Genotype IIIA is rarely seen in Denmark and has previously been associated with HAV patients who had been travelling in the Middle East. Through intensive research including patient interviews, a case-control study and trace-back investigation, the source was identified only one week after the outbreak had been identified. The source of infection was dates from Iran provided by a specific producer, and the dates were recalled on 6 February 2018. The same virus was found in a pack of dates from a patient’s home. Read more about the outbreak in EPI-NEWS 11/18.

Hepatitis A outbreak with suspicion of fresh strawberries

Following the above-described outbreak with genotype IIIA, another outbreak was recorded from March to June 2018. Here, a total of 10 persons were affected by genotype IA. The patients were 8-72 years old, six were women and four men. A limited number of patients were seen in other European countries. In-depth patient interviews, including a study at an institution where several of the patients were residing, produced a heavily substantiated suspicion that the source of infection was fresh foreign strawberries produced in non-EU-countries - this, however, could not be confirmed and the outbreak ended without control measures.

European hepatitis A outbreak among men who have sex with men

Since 2016, a large HAV outbreak with genotype IA has been reported in Europe among men who have sex with men (MSM). More than 4,400 HAV cases have been reported in a total of 22 EU countries, also see EPI-NEWS 10/17, and the European Centre for Disease Prevention and Control (ECDC) rapid risk assessment. In Denmark, virus typing and sequencing have linked 12 of the patients from 2017 and 12 from 2018 to this outbreak. The patients who formed part of the outbreak were 16-67 years of age; all but one were men, and 15 patients were notified as MSM. In general, there is a considerable risk of sexual infection with hepatitis A virus in the MSM community, and men who engage in rimming (sexual oral-anal contact) are at an increased risk.

Virus typing

In 2017 and 2018, the laboratory at the Department of Virus and Microbiological Special Diagnostics received a total of 159 samples from patients with presumed HAV infection. HAV-RNA was detected in 85 samples in 79 of which virus could be sub-typed. Forty of these were due to type 1A, 11 were type 1B and 28 were type 3A (Table 2).


This report is also described in EPI-NEWS 51/19.