Latent class analysis of human herpesvirus 8 assay performance and infection prevalence in sub‐Saharan Africa and Malta

Human herpesvirus 8 (HHV‐8) is thought to be highly prevalent in Mediterranean countries and sub‐Saharan Africa, where it causes Kaposi's sarcoma in a small proportion of infected immunocompetent persons. However, the lack of serological tests with established accuracy has hindered our understanding of the prevalence, risk factors and natural history of HHV‐8 infection. We tested 837 subjects from Congo, Botswana (mostly young adults) and Malta (elderly adults), using an immunofluorescence assay and 2 enzyme immunoassays (EIAs, to viral proteins K8.1 and orf65). Each assay found HHV‐8 seroprevalence to be high (49–87%) in the African populations and generally lower (9–54%) in Malta. However, there was only modest agreement among tests regarding which subjects were seropositive (3‐way κ, 0.05–0.34). We used latent class analysis to model this lack of agreement, estimating each test's sensitivity and specificity and each population's HHV‐8 prevalence. Using this approach, the K8.1 EIA had consistently high sensitivity (91–100%) and specificity (92–100%) across populations, suggesting that it might be useful for epidemiological studies. Compared with the K8.1 EIA, both the immunofluorescence assay and the orf65 EIA had more variable sensitivity (80–100% and 58–87%, respectively) and more variable specificity (57–100% and 48–85%, respectively). HHV‐8 prevalence was 7% among elderly Maltese adults. Prevalence was much higher (82%) in Congo, consistent with very high Kaposi's sarcoma incidence there. Prevalence was also high in Botswana (87% in Sans, an indigenous group, and 76% in Bantus), though Kaposi's sarcoma is not common, suggesting that additional co‐factors besides HHV‐8 are needed for development of Kaposi's sarcoma. Int. J. Cancer 88:1003–1008, 2000. © 2000 Wiley‐Liss, Inc.