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 Mediterran ean 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 immunoassay s (EIAs, to viral proteins K8.1 and orf65). Each assay found HHV-8 seroprev alence to be high (49-87%) in the African populations and generally lower ( 9-54%) in Malta. However, there was only modest agreement among tests regar ding which subjects were seropositive (3-way kappa, 0.05-0.34). We used lat ent class analysis to model this lack of agreement, estimating each test's sensitivity and specificity and each population's HHV-8 prevalence. Using t his approach, the K8.1 EIA had consistently high sensitivity (91-100%) and specificity (92-100%) across populations, suggesting that it might be usefu l for epidemiological studies. Compared with the K8.1 EIA, both the immunof luorescence assay and the orf65 EIA Rad 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. Prev alence was much higher (82%) in Congo, consistent with very high Kaposi's s arcoma incidence there. Prevalence was also high in Botswana (87% in Sans, an indigenous group, and 76% in Bantus), though Kaposi's sarcoma is not com mon, suggesting that additional co-factors besides HHV-8 are needed for dev elopment of Kaposi's sarcoma. Int. J. Cancer 88:1003-1008, 2000, Published 2000 Wiley-Liss, Inc.dagger