Hepatitis C 2019-2020 - acute and chronic

Annual Report on hepatitis C in Denmark 2019-2020

In 2019, the Department of Infectious Disease Epidemiology and Prevention received 123 notifications of chronic hepatitis C. In 2020, the corresponding figure was 165 notifications.

Acute hepatitis C

Notified cases of acute hepatitis C are usually asymptomatic cases detected by screening in connection with, e.g., dispensing of prophylactic medicine against HIV infection (PrEP), HIV infection testing, etc. These cases are considered acute as a recent negative hepatitis C test exists.

In 2019, a total of 11 cases (including seven men) were notified with acute hepatitis C. In 2019, the median age was 44 years (range 28-52 years). Ten cases were notified as having become infected in Denmark and one as having become infected abroad (in Thailand). With respect to presumed mode of transmission, five cases were notified as men who have sex with men (MSM), four as intravenous drug users, one as heterosexual contact (presumed infection following sex with a person known to be infected with hepatitis C) and one case as an accident involving blood. The latter case was a tourist who had become infected abroad. Among the five cases who were notified as having become infected through homosexual contact, three were infected with HIV, whereas two did not have HIV.

2020 saw three notified cases (all men) of acute hepatitis C. Their median age was 43 years. Two were notified as having become infected in Denmark, including one with homosexual contact as the presumed mode of transmission (non-HIV infected) and one with intravenous drug use. The final case was notified with unknown mode and country of transmission as the case was established in a deceased person, and it remains unknown whether the case was in fact acute or chronic.

Chronic hepatitis C

In 2019, a total of 112 cases of chronic hepatitis C were notified. The corresponding number for 2020 was 162. Among these, 80 (71%) in 2019 and 118 (73%) in 2020 were men. Since 1991, the share of men has remained between 63% and 73% of the notified cases of chronic hepatitis C.
In 2019, the median age was 49 years for men (range 21-78 years) and 42 years for women (range 22-67 years). In 2020, the median age for men was 50 years (range 23-68 years) and for women 45 years (range 23-75 years), Figure 1a and b.

The median age for chronic hepatitis C has increased gradually over the years from nearly 40 years in 1991 to nearly 50 years. Similarly, the median age for acute hepatitis C has increased from nearly 35 years to nearly 45 years, Figure 2.

Table 1 presents the distribution by region and area and the notification incidence per 105 citizens.

Transmission

In 2019, the presumed country of infection was stated for 86 notified cases (77%). Among these cases, a total of 66 (77%) had acquired the infection in Denmark, whereas 20 (23%) had become infected in one of 13 other countries. In 2020, the presumed country of infection was stated for 139 notified cases (86%). Among these, a total of 117 (84%) had acquired the infection in Denmark, whereas 22 (16%) had become infected in one of 16 other countries.

Table 2 presents an overview of presumed country of infection.

Over time, the share of notified cases who were presumably infected in Denmark has decreased from approx. 95% around 2000 to approx. 75% in 2020.

In the same period, the share of notified cases who were presumably infected in Eastern Europe has increased from approx. 1% around 2000 to approx. 7% around 2020. The share in the remaining regions has remained largely stable, Figure 3. The share of notifications with unknown or unstated country of infection has increased steadily from between 0% and 7% in the period leading up to 2009 to between 6% and 23% in the past five years.

Mode of transmission is presented in Table 3.

IV drug use was the most frequent mode of transmission with 80 (71%) cases in 2019 and 123 (76%) cases in 2020 of the notified persons. Of these, 52 (65%) in 2019 and 100 (81%) in 2020 had become infected in Denmark.

In 2019, one (0.9%) person was notified with a nosocomial infection due to a blood transfusion abroad. In 2020, six (4%) persons were notified as nosocomially infected cases. One person was notified as having presumably become infected in Denmark via a blood transfusion 25 years ago. The remaining cases were notified as having become infected abroad through blood transfusion or surgery mainly conducted in Eastern Europe.

In 2019, four (4%) persons were notified as having become infected through heterosexual contact, including two in Denmark and two for whom the country of infection was unknown. The HIV status of one case was unknown, whereas the others did not have HIV, and no information was provided about intravenous drug use. In 2020, another four (2%) persons were notified as having become infected through heterosexual contact, all of whom had become infected in Denmark. None had HIV, and no information was provided about intravenous drug use.

In 2019, two persons (2%) were notified as having become infected as MSM, both in Denmark, none of whom had HIV. In 2020, no one was notified as having become infected as MSM.

In 2019, no cases of mother-to-child transmission were notified, whereas 2020 saw a total of five (3%) cases. One of these cases had presumably become infected in Denmark by the mother who was a former drug user. This person was diagnosed at adult age. The other cases were also detected in adult persons born in other countries, primarily African countries.

In 2019, four cases (4%) were notified as having become infected via tattooing, including three cases infected in Denmark. For two of these cases, it was stated that the tattooing occurred many years ago, whereas no additional information was provided for the final case. For the fourth case, country of infection was stated as unknown; transmission had occurred abroad.
In 2020, seven cases (4%) were notified as having become infected via tattooing, including one case who had become infected in Denmark. No further information was provided about this case. The other cases were notified as having become infected in Eastern Europe, Sweden (at an unauthorised tattoo artist), Pakistan and Thailand.

In 2019, the mode of transmission was unknown or not stated for 21 persons. Six of these persons had presumably become infected in Denmark, whereas the others had presumably become infected in the Middle East, Asia or Russia, whereas the country of infection was unknown for five cases. Eleven were known HIV negatives, whereas the HIV status of ten was unknown.
Among the 17 persons for whom the mode of transmission was unknown or had not been stated in 2020, ten had presumably become infected in Denmark, whereas the others had also presumably become infected in Eastern Europe, Asia or Thailand; and for two cases the country of infection was unknown. Five were known HIV negatives, whereas the HIV status of the others was unknown.

Among persons who were presumably infected in Denmark, the share of notifications stating intravenous drug use as the mode of transmission decreased from 2000 to 2008, after which the share stabilised. Since 2010, the share has remained at approx. 80-85%, Figure 4.

This report is also described in EPI-NEWS 34/21.