HHV8 seropositivity was positively associated with reporting multiple marital unions and with each unit increase in the total number of children born. Conversely, it was inversely associated with having ever used a condom. These associations were independent of HIV, HSV2 and of age, sex, and region of residence 
. HIV and HSV2, both strong markers of sexual transmission, were unrelated to HHV8 seropositivity. We interpret these results as clues for a role of sexual transmission of HHV8 in Uganda, in accord with findings from several other studies 
The inverse association with condom use is not new. Beaten and co-workers 
have reported that HHV8 seropositivity was 30% decreased among Kenyan truck drivers who reported using a condom compared with those who did not, which suggested that condom use might protect from HHV8 infection. This finding was not replicated in two other studies that evaluated the hypothesis among female prostitutes from Kenya 
and adults with cancer at hospitals in Kampala, Uganda 
, which casts doubt on its validity. Our results obtained from a large geographically heterogeneous population-based study conducted in Uganda where endemicity both of HHV8 and KS is high but variable 
suggest that condom use and/or behavior correlated with the tendency to use condoms may protect from HHV8 seropositivity.
We noted, similar to previous studies conducted inside 
and outside Uganda 
, that HHV8 seropositivity was not associated with lifetime number of sexual partners, reporting a history of any STD, or a positive laboratory test for HIV and HSV2. These null findings with HHV8 contrast sharply with the strong, positive, and consistent associations demonstrated between HIV infection questionnaire and laboratory sexual risk factors that have been reported from this cohort 
. The null or ambiguous associations between HHV8 seropositivity and sexual variables suggest that sexual transmission of HHV8 in Uganda, if it occurs, is weak. The ambiguous HHV8 associations in our study and in the literature highlight the difficulty of investigating sexual transmission of HHV8 in populations where non-sexual HHV8 transmission predominates. HHV8 seropositivity in the cohort restricted to sexually active individuals was similar to that observed in the cohort when both sexually active and sexually naïve individuals were included (56.2% vs. 55.4%) 
. In both analyses, HHV8 seropositivity increased significantly with age. The reasons for the age-related increase in HHV8 seropositivity are unclear to us, but they may include a cohort effect (older people who may have been exposed to higher HHV8 transmission risks during childhood), or HHV8 reactivation, which may cause sero-conversion or increase of anti-HHV8 antibody titers, as people age, or new infections.
We observed a small but significant association between HHV8 seropositivity with each unit increase in the total number of children born. This result may indicate a greater propensity for intra-familial HHV8 transmission in families with many children 
, or it may be due to residual confounding with age. HHV8 seropositivity was unrelated to wealth index score and to drinking water from a surface water source; both measures of socioeconomic status. Most HHV8 transmission in Uganda occurs during childhood 
; therefore, assuming that most HHV8 infections in our sample occurred during childhood, and that only a minority occurred during adulthood, this impedes our ability to find small, albeit, significant associations between current socioeconomic status and adult HHV8 transmission. Our fully adjusted model did not account for all variation in HHV8 seropositivity. About 20% of variance in HHV8 seropositivity was correlated with geographical clusters. This correlation indicates proneness to HHV8 seropositivity among individuals living in some geographical clusters. Some of us have speculated that geographical clustering of HHV8 seropositivity, which is observed at the macro 
and micro level 
, may be due to helminthic parasites. Co-infection with parasites may influence HHV8 transmission by modulating host immunity 
and viral control and shedding among seropositive individuals 
, or susceptibility at low levels of HHV8 exposure among uninfected individuals.
We acknowledge some caveats about our data. First, the results were from a cross-sectional study and the temporal relationship between correlated variables cannot be determined. Second, HHV8 serological methods are imperfect 
. We used two lytic HHV8 enzyme immunoassays, which have been used with reasonably high sensitivity and specificity in several other studies of HHV8 conducted in Uganda 
. Our results are comparable with those from studies of individuals from regions where data are common to both studies 
. Errors in classification cannot be excluded, but they would have been random and biased the associations towards the null, thus, making it difficult to demonstrate small effects. The strengths of our study include access to a nationally representative sample with detailed questionnaire and laboratory results for STDs from a country with well-characterized KS epidemiology before the AIDS epidemic. Sexual behavior was documented meticulously and associations between sexual risk factors with prevalent and incident HIV infection suggest that sexual exposure was measured reliably 
. Detailed information about socioeconomic, geographical, and environmental confounders was available and was used to adjust for confounding more than is normally possible in epidemiological studies conducted in Africa.
In conclusion, we observed positive associations between HHV8 seropositivity with two marital unions and the number of children ever born, and an inverse association with condom use in a representative cohort of sexually active Ugandans. HIV and HSV2 were unrelated to HHV8 seropositivity. We interpret our results as indicating that sexual transmission of HHV8 in Uganda, if it occurs, is weak.