Despite increasing numbers of human immunodeficiency virus (HIV)–infected South Africans receiving antiretroviral therapy (ART), tuberculosis (TB) remains the leading cause of mortality. Approximately 25% of patients treated for TB have microbiologically unconfirmed diagnoses. We assessed whether elevated Kaposi’s sarcoma–associated herpesvirus (KSHV) viral load (VL) contributes to mortality in hospitalized HIV-infected patients investigated for TB.

Six hundred eighty-two HIV-infected patients admitted to Khayelitsha Hospital, South Africa, were recruited, investigated for TB, and followed for 12 weeks. KSHV serostatus, peripheral blood KSHV-VL, and KSHV-associated clinical correlates were evaluated.

Median CD4 count was 62 (range, 0–526) cells/μL; KSHV seropositivity was 30.7% (95% confidence interval [CI], 27%–34%); 5.8% had detectable KSHV-VL (median, 199.1 [range, 13.4–2.2 × 10⁶] copies/10⁶ cells); 22% died. Elevated KSHV-VL was associated with mortality (adjusted odds ratio, 6.5 [95% CI, 1.3–32.4]) in patients without TB or other microbiologically confirmed coinfections (n = 159). Six patients had “possible KSHV-inflammatory cytokine syndrome” (KICS): 5 died, representing significantly worse survival (P < .0001), and 1 patient was diagnosed with KSHV-associated multicentric Castleman disease at autopsy.

Given the association of mortality with elevated KSHV-VL in critically ill HIV-infected patients with suspected but not microbiologically confirmed TB, KSHV-VL and KICS criteria may guide diagnostic and therapeutic evaluation.