[Imported diseases].

In Denmark, about one third of notifiable diseases are imported, but these have had only a limited spread within the Danish community. For example, imported strains of Mycobacterium tuberculosis remain confined to the immigrant population, and the high prevalence of chronic hepatitis B among certain groups of immigrants has not resulted in a general increase in the incidence of hepatitis B. Exceptions are imported cases of hepatitis A in children, which have resulted in outbreaks in the indigenous Danish population, and the import of drug-resistant bacteria, which often pose a serious challenge to hospital hygiene.