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Abstract
Human herpesvirus-8 and Epstein-Barr virus are oncogenic gamma-herpesviruses that have been associated with Kaposi's sarcoma and AIDS-related non-Hodgkin lymphomas respectively. Therefore, it is of interest to understand the natural history of infection of these two gamma-herpesviruses in an endemic area like Zambia which is experiencing a human immunodeficiency virus (HIV) epidemic, and a dramatic rise in AIDS-associated cancers. Here, we report results from a prospective study to investigate the epidemiology and transmission of human gamma-herpesviruses in a mother-infant cohort, conducted between 1998 and 2004, in Lusaka, Zambia.
For the reliable serological diagnosis of HHV-8 infection a novel insect cell-based monoclonal-enhanced immunofluorescence assay (mIFA) was developed as a part of an algorithm to identify the true positive cases. Results from children in this cohort, who were followed from birth through 48 months of age show that HHV-8 seroconversion occurs early in life and the incidence of HHV-8 seroconversion is 13.8 infections per 100 child-years. Seroconversion in adult women was comparatively lower, indicating that primary infection occurred during childhood. HIV-1 infection was a major risk factor in acquiring HHV-8 infection in both children and in adults. Maternal HIV-1 and HHV-8 infection status were not independently associated with risk of HHV-8 seroconversion in the child.
HHV-8 antibody titers measured by following children and adults at all consecutive time-points revealed that seroreversion occurred frequently. This may lead to underestimation of HHV-8 seroprevalence in cross-sectional studies. Thus, HHV-8 prevalence studies based on analysis at just one time point may not give a true representation of the HHV-8 infection rates in a population.
While HHV-8 and EBV have similar modes of transmission, we observed a significantly higher seroprevalence of EBV (60% at 12 months) in children. Thus the transmission for EBV is either more effective or occurring at a much higher rate as compared to HHV-8. Also, HIV-1 infection of the mother and not of the child was a risk factor in acquiring EBV infection probably due to increased shedding by the mother.
