Infection with AIDS-related herpesviruses in human immunodeficiency virus-negative infants and endemic childhood Kaposi's sarcoma in Africa

Novel herpesviruses have been described recently. These include human herpesviruses 6, 7 and 8 (HHV-6, -7, -8), HHV-6 has at least two strain groups, variants A and B. The B strains are predominant in the West and can account for over 97% of infections in infants. In contrast, the A strains are rare and the few well-characterized isolates have been from adult African AIDS patients. It is not clear whether the HHV-6 variant A strains are AIDS-related and/or whether they can also be acquired as childhood infections and may reactivate later during adulthood. What contribution geographical variation plays has yet to be assessed. HHV-8 has been associated with AIDS-related epidemic Kaposi's sarcoma (KS), but has also been identified in endemic KS. In regions of Africa where KS is endemic, the onset of AIDS has led to increased prevalence of KS. In this report, we examine in Zambia, an AIDS epidemic and KS endemic region, infection with these novel herpesviruses during infancy. In blood samples from human immunodeficiency virus-negative infants with first febrile episode, both semi-quantitative PCR and sequence analyses were used to identify HHV-8 in 8% and HHV-6 in 30%, with 44% of these variant A; in childhood endemic KS biopsies HHV-8 was detected in 100% and HHV-6 in none. The high viral-DNA loads in the infant blood samples were consistent with viraemia. This is the first demonstration that HHV-6 variant A and HHV-8 may be acquired as common childhood infections.