Human herpesvirus 8 (HHV-8) salivary shedding in mothers and children from Uganda: risk factors and clues about transmission

Background: in Africa, the increase of Kaposi Sarcoma-associated herpesvirus (KSHV/HHV-8) sero-prevalence during childhood suggests an horizontal intrafamilial transmission. However, the exact transmission modes are yet unknown, but there is evidence that the virus is intermittently spread through the saliva of seropositive subjects. Furthermore, a significant correlation was found between the geographical distribution of bloodsucking arthropods and incidence rates of Kaposi Sarcoma. In this view, key roles can be played by: i) the inflammatory reaction due to the arthropod bites which create a micro-environment favourable to viral replication, and ii) the use of saliva as first-aid medication in several circumstances. According to that, the viral transmission could occur through the application of mothers’ saliva on children’s skin to relieve itching and scratching after a bloodsucking arthropod bite. This work investigated the risk factors involved in HHV-8 transmission based on the “promoter arthropod hypothesis”. Methods: one hundred and thirty questionnaires were administered to Ugandan children (54 from settled and 76 from nomad communities) to evaluate the skin inflammatory reaction to the arthropod bites and the frequency of behavioural practices associated with saliva usage. At the same time saliva samples were collected from the children and respective mothers to detect the presence of HHV-8 DNA by Real-Time PCR. Results: we detected HHV-8 DNA in 23.85% of mothers and in 11.54% of children. The use of saliva is significantly more common in settled than in the nomad communities (p<0.001). The statistical analysis showed significant association between: i) skin inflammatory reaction and use of saliva in both groups; ii) environmental factors which increase the presence of bloodsucking arthropods and skin inflammatory reaction. Discussion: from our data we suppose that HHV-8 transmission could occur through non-sexual routes and that the infected saliva applied at child bite site could represent a favourable condition for the acquiring of the infection.