Hepatitis C 2021-2022
Annual report on hepatitis C in Denmark 2021 and 2022
Hepatitis C is caused by infection with hepatitis C virus (HCV). HCV causes hepatitis, which only rarely presents as an acute condition. The majority of cases acquire a chronic infection that is diagnosed only many years after transmission. In 2021, the Department of Infectious Disease Epidemiology and Prevention received 150 notifications of hepatitis C. In 2022, the corresponding figure was 207 notifications.
Acute hepatitis C
In acute infection, HVCV RNA may be detected as from few days and until eight weeks after transmission and the infection persists in the majority of cases. Anti-HCV antibodies may not be detected until 4-12 weeks have passed. 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 if a recent negative hepatitis C test exists.
2021 saw four notified cases of acute hepatitis C; two men and two women. The median age was 36 years (range 35-51 years), Figure 1. All had become infected in Denmark. Three of the cases presumably became infected by intravenous drug use and one case by sexual contact.
In 2022, 11 cases of acute hepatitis C were notified; eight men and three women. Among the 11 notified cases of acute hepatitis C, one case was from 2015 but was not notified until 2022. The median age of those notified in 2022 was 40 years (range 28-62 years), Figure 1. The majority was notified as having become infected in Denmark. Seven cases had presumably become infected by intravenous drug use, three by sexual contact and one by a sharps accident (not an occupational accident in a healthcare professional).
Chronic hepatitis C
Chronic HCV infection is defined as detectable levels of HCV RNA for a period exceeding six months.
In 2021, 146 cases of chronic hepatitis C were notified. Among these cases, 105 (72%) were men. The median age was 51 years and the age range was 22-83 years, Figure 1. For men, the median age was 50 years (range 24-83 years) and for women it was 56 years (range 22-76 years).
In 2022, 196 cases of chronic hepatitis C were notified. Among these cases, 131 (67%) were men. The median age was 51 years and the age range was 21-82 years, Figure 1. For men, the median age was 50 years (range 24-80 years) and for women it was 53 years (range 21-82 years).
Sex and age distribution among the notified cases in 2021 and 2022 are presented in Figures 2a and b.
Region and area
Presumed country of infection
A presumed country of transmission was stated for 125 (85%) of the notified chronic hepatitis C cases in 2021. Among these, a total of 111 (89%) had acquired their infection in Denmark. In 2022, information about presumed country of transmission was provided for 190 of the notified chronic hepatitis C cases (97%). Among these, a total of 153 (81%) had acquired their infection in Denmark.
Figure 3 presents the development of notified cases of chronic hepatitis C who became infected in Denmark and abroad.
Mode of transmission
In 2021, the mode of transmission was unknown or not stated for 31 persons (21%). Sixteen of these persons had presumably become infected in Denmark, whereas the others had presumably become infected in European countries. Finally, the country of infection was unknown for ten cases. Among the 24 persons (12%) for whom the mode of transmission was unknown or not stated in 2022, seven had presumably become infected in Denmark. The remaining cases had primarily become infected in other European countries but also in Asia, the Middle-East and on the African continent. Four cases were notified with unknown country of transmission.
In 2021, presumed mode of transmission was stated for 115 cases (79%). The corresponding number in 2022 was 172 (88%).
Intravenous drug use
Intravenous drug use remains the most frequent mode of transmission with 97 cases (84% of the cases notified with known mode of transmission) in 2021 and 154 cases (89%) in 2022. Of these, 84 (87%) in 2021 and 136 (88%) in 2022 had become infected in Denmark.
Sexually transmitted infection
2021 recorded three cases in which the source of infection was sexual transmission. All of these cases had become infected in Denmark. In contrast, 2022 saw six cases; most of which had become infected in Denmark. This comprised heterosexual transmission and transmission among men who have sex with men (MSM).
In 2021, one case of mother-to-child transmission was notified in Denmark. In 2022, three such cases were notified, two of whom were born abroad, whereas the third was born in Denmark, but by a mother who was a previous drug user. All cases recorded in 2021 and 2022 were detected in adult age.
Other modes of transmission
In 2021, five persons were notified with nosocomial infection (infection acquired in a hospital setting). In 2022, two such cases were recorded. All cases of nosocomial infection occurred abroad.
A total of four cases were notified as transmission by tattooing in 2021 and two cases in 2022. The cases had either become infected abroad or in Denmark many years ago.
Figure 4 presents the development in modes of infection for chronic hepatitis C cases from 2000 to 2022.
This report is also described in EPI-NEWS 18/2023.