Clusters and outbreaks of hepatitis A virus (HAV) genotype IB have been reported in six European Union (EU) nations including the United Kingdom, with four distinct but closely related HAV sequences (UK).
As of September 29, 2022, 303 cases of the same or closely related HAV strains have been detected in Austria (7), Germany (8), Hungary (161), the Netherlands (8), Slovenia (35), Sweden (8), and the United Kingdom (76).
Human-to-human transmission, as well as transmission through contaminated food, is suggested by currently available epidemiological and microbiological evidence.
Hungary reported an epidemic of HAV genotype IB on 15 February 2022, with the first case appearing in early December 2021. To far, the National Hepatitis Reference Laboratory in Hungary has confirmed 161 cases (139 men, 22 females) with this strain. Since June 2022, the weekly number of reported hepatitis A cases has been decreasing. Several infected patients identified as men who have sex with men (MSM), indicating that infection may spread via sexual encounters. Several people have been admitted to hospitals.
A foodborne epidemic was detected in July 2022, with a relation to a restaurant in Hungary where 16 individuals were sick with HAV IB infection. Some of the patients said they ate cold soup prepared with frozen berries.
In the United Kingdom, no single source of infection has been discovered, however epidemiological studies have shown the possibility of foodborne infections in addition to person-to-person transmission. Germany, the Netherlands, and Sweden have all reported nine instances of infection with strains that match the sequences of the UK strain.
Investigations into these patients revealed no evident risk factors for infection, such as a history of travel or berry consumption. Additional investigations are being conducted.
HAV is highly transmissible through contaminated water, food, and the faecal-oral route among close contacts (e.g., home contacts, sexual contacts, and contacts in day-care centres or schools), with an incubation period ranging from two to six weeks on average. The virus is very resistant to environmental factors as well as various preservation procedures such as acidification or freezing. When numerous cases are recorded in a short period of time, probable food-borne transmission should be examined.
Good hand hygiene, which includes thoroughly washing hands with soap after using the bathroom, changing diapers, and before preparing or eating food, is important in avoiding the spread of hepatitis A.
It is critical to increase monitoring to identify and examine sporadic and clusters of cases that may be related to foodborne transmission in coordination with food safety authorities.
When MSM engage in sexual acts that enhance faecal-oral transmission of the virus, they are at risk of HAV infection. In the context of the present spread of HAV genotype IB among MSM, the major choice for reaction is hepatitis A vaccine, which is both safe and very effective. Hepatitis A immunisation is recommended for MSM by the World Health Organization and the majority of EU/EEA nations.
Other measures, in addition to vaccination, may help to prevent transmission among MSM: the use of condoms during anal intercourse, which has the added advantage of protecting against other sexually transmitted illnesses, and excellent personal cleanliness (e.g. washing hands and genital areas before and after sex).
Authorities should consider collaborating with civil society, social media, media outlets, and dating apps to promote awareness among MSM about the danger of developing HAV and the need of immunisation in order to provide primary prevention guidance. MSM who have previously been infected should be referred to sexual health professionals for further testing.
Hepatitis A is a liver infection caused by the hepatitis A virus, a small, non-enveloped hepatotropic virus classified in the genus Hepatovirus and the family Picornaviridae.
