Abstract:
Background: The association of the human herpesvirus-8/Kaposi's sarcoma (KS)-associated herpesvirus
(HHV-8/KSHV) serology with various malignancies in Tanzania is not currently well established while
previous studies were based on either PCR or immunofluorescence assays [IFA] but not with a sensitive
enzyme-linked immunosorbent assay (ELISA). Selected archival diagnostic biopsies (n = 184) and sera from
indigenous patients with KS (n = 120), non-KS tumors (n = 24) and non-neoplastic lesions (n = 40) at
Muhimbili National Hospital (MNH), Tanzania, were evaluated by diagnostic histopathology,
immunohistology [anti-HHV-8 latency-associated nuclear antigen (LANA)] and serology for HIV (ELISA)
and HHV-8 (IFA and ELISA).
Results: About 66.3% (n = 122) cases including AIDS-associated Kaposi's sarcoma (AKS) (n = 93), reactive
conditions (n = 28) and only one non-KS tumour were HIV positive. Endemic KS (EKS) patients were
mostly males (96.3%, 26/27) who were less (69.9%, 65/93) predominant in AIDS-associated (AKS). A high
(89%) percentage of patients with anti-HHV-8 antibodies was found in the cohort including the HIV
positive (92%) cases, males (81.2%), KS patients (93%), non-KS tumors (92%), and reactive conditions
(75%). All HHV-8 seronegative KS cases were nodular stage whereas both sera and corresponding biopsies
from early stage KS were HHV-8+. Assay sensitivity, positive predictive value (PPV) and specificity were
98.6%, 93.5% and 16.7% for IFA and 93.5%, 98.6% and 50.0% for ELISA respectively.
Conclusion: HHV-8 seroprevalence at MNH appears high as expected among AKS cases and males but
also in non-KS patients. ELISA showed a combination of high HHV-8 sensitivity as well as higher PPV and
specificity than IFA which however, showed higher sensitivity. The apparent stage-dependent, inverted
serum HHV-8 immunoreactivity supports a notion of viral immune-segregation during KS development.
Routine HHV-8 screening should be considered particularly in patients at risk of KS and for selection of
blood/organ donations.
