Background:  It has been established that Kaposi's sarcoma-associated herpesvirus (KSHV) infection is endemic among most African adult populations. The prevailing view is that a single mode of KSHV spread—horizontal transmission in childhood—is primarily responsible for endemic infection throughout the continent. However, few studies have directly examined children, particularly in population-based samples in areas where the endemic form (non-HIV-related) of Kaposi’s sarcoma is uncommon.

Methods:  To study a region where endemic Kaposi’s sarcoma is uncommon, we obtained a door-to-door sample of children ages 2, 4, or 8 years, and their female caregiver, in the KwaZulu-Natal region of South Africa. As a comparison group where endemic Kaposi’s sarcoma is common, children younger than age 10 were sampled at Mulago Hospital in Kampala, Uganda. Plasma was tested for KSHV antibodies with 2 enzyme immunoassays (using K8.1 andORF65 peptides) and an immunofluorescence assay using induced BCBL-1 cells, all performed at the Centers for Disease Control and Prevention. South African samples were also tested by ORFK8.1 and ORF73 enzyme immunoassays at the National Cancer Institute.

Results:  A total of 452 South African children (159 2-year-olds, 153 4-year-olds, and 140 8-year-olds) were evaluated. Overall KSHV seroprevalence was 6.4%, which did not differ by age among all children (6.3%, 6.5%, and 6.4% in the 3 age groups, respectively; p = 0.96 for trend) or separately among urban or rural children. Lack of age dependence was replicated with KSHV testing at NCI. Among the children’s caregivers, KSHV seroprevalence was 18%. In contrast, in 1291 Ugandan children, seroprevalence among 2-year-olds (10%) was already nearly 50% higher than that of South African 8-year-olds and increased with age:  16% at 4 years and 27% at 8 years old (p = 0.01 for trend).

Conclusions:  In a contemporary population-based sample in South Africa—where the endemic form of Kaposi’s sarcoma is uncommon—there is lack of age dependence and low overall seroprevalence of KSHV infection among children, suggesting little ongoing horizontal KSHV transmission in childhood. Higher KSHV seroprevalence is only seen in adults. This differs from Uganda where seroprevalence is 10% by age 2 and further increases in childhood. The findings indicate at least 2 patterns of KSHV transmission exist in Africa, which, at least preliminarily, track with underlying incidence of endemic Kaposi’s sarcoma. Whether KSHV infection in childhood is a critical determinant for Kaposi’s sarcoma development as an adult, and is in part responsible for the high incidence of endemic Kaposi’s sarcoma seen in areas like Uganda, merits further investigation.