Human herpesvirus 8 (HHV8), the etiological agent of Kaposi's sarcoma (KS), is transmitted mainly during childhood from seropositive family members, especially the mother, through saliva. The seroprevalence of HHV8 infection to a large extent reflects the distribution of KS, showing the same geographical variation. Although the exact prevalence of HHV8 and incidence of KS remain to be established in many geographical areas, very high rates were reported in sub-Saharan Africa [Dedicoat and Newton, 2003] and intermediate rates in Mediterranean countries including Italy [Calabro `et al., 1998;Dal Maso et al., 2005]. As far as Nordic contexts are concerned, there is evidence that the incidence of classic KS is not negligible and that HHV8 circulates in the general population.
In Sweden, considerable within-country variations in the incidence of KS have been reported, with rates significantly higher in the northern region of Umea (latitude 62-688N) than in the southern parts [Hjalgrim et al., 1996]. Possible determinants for such variability in KS that decreases southwards have not been identified. In the March 2006 issue of the Journal of Medical Virology, Tedeschi et al. [2006] report the prevalence for HHV8 infection in a population-based serosurvey in the Vasterbotten county (latitude 64-668N), region of Umea, northern Sweden. The aim of the study was to test whether the higher KS risk in northern Sweden reflects high prevalence of HHV8 infection. Seroprevalence figures were defined as high/intermediate, they were not significantly associated with sex or age but indeed mirrored the rather high incidence of KS in this area. The analyses of risk factors for viral spread that were restricted to lifestyle variables, showed little association with decreasing levels of education and negative/positive associations with other factors. However, none of the variables seemed to explain the distribution of HHV8 in this Nordic population.
Before the AIDS epidemic, remarkable geographical variations in the incidence of KS have been reported in four Scandinavian countries (Sweden, Norway, Finland, and Denmark), with Sweden having the highest and Denmark the lowest rates [Hjalgrim et al., 1996].