Unique impacts of HBV co-infection on clinical and laboratory findings in a recent dengue outbreak in China.

High prevalence of hepatitis B virus (HBV) infection in China offers a unique setting to examine HBV's influence on the presentation of dengue fever. In 398 patients admitted for suspected dengue fever, 89% (353/398) were positive for dengue IgM antibodies. Among dengue-infected patients, 8% (29/353) had chronic HBV co-infection. Only dengue virus serotype 1 was identified by virus isolation and reverse transcriptase-polymerase chain reaction assays. No case of dengue hemorrhagic fever/dengue shock syndrome was diagnosed. In addition to routine clinical tests, interleukin 2 (IL-2), IL-4, IL-6, IL-10, interferon gamma (IFNgamma), and tumor necrosis factor alpha (TNFalpha) levels were measured in the sera of 95% (334/353) of dengue-infected subjects as well as controls. Surprisingly, HBV/dengue co-infected patients made less IL-6 (P < 0.05) and TNFalpha (P < 0.05) than patients with only dengue infection. Similar levels of IL-4, IL-10, and IFNgamma were found in both groups. Thus, HBV co-infection seems to alter the cytokine production pattern when patients contract dengue infection.