Epidemiology of human herpesvirus 6 (HHV-6) infection in pregnant and nonpregnant women

Background: Human herpesvirus 6 (HHV-6) is a ubiquitous virus primarily ass ociated with benign conditions such as febrile syndromes and exanthem subit um (roseola infantum). Sexual, horizontal, and vertical transmission have b een suggested. Little information is available regarding HHV-6 infection in women of reproductive age. Objective: Describe epidemiology of HHV-6 infec tion in pregnant and nonpregnant women. Study design: The study sample cons isted of 569 women, age 18-45, who attended a university family planning cl inic (nonpregnant, n = 224) and two obstetrics clinics (pregnant [first tri mester], n = 345) in San Antonio, TX between October 1995 and May 1998. Blo od and a vaginal swab, as well as sociodemographic information, were collec ted from each participant. Plasma was tested for HHV-6 IgG antibodies using a standard immunofluorescence assay (IFA). Lysed material from vaginal swa bs was tested for HHV-6 DNA by polymerase chain reaction (PCR). Products we re screened by enzyme-linked immunosorbent assay and positive tests were co nfirmed by repeat PCR followed by Southern analysis. PCR-positive samples w ere subtyped using an established method. Results: All subjects were HHV-6 antibody positive. Geometric mean titers of HHV-6 antibodies were significa ntly higher among nonpregnant versus pregnant women. Moreover, a higher pro portion of nonpregnant versus pregnant women had antibody titers greater th an or equal to 160 and greater than or equal to 320. This association persi sted even after adjusting for a number of sociodemographic and clinical fac tors. Low rates of HHV-6 shedding in the genital tract were observed for bo th groups (pregnant, 7/297 [2.0%]; nonpregnant, 8/214 [3.7%]). Of 14 sample s subtyped, four (29%) were subtype A. Conclusion: The present study showed that 100% of the study sample was infected with HHV-6. Higher HHV-6 antibo dy titers, however, were noted in nonpregnant women. Both groups shed virus at low rates in the genital tract. HHV-6 subtype A was identified more com monly than previously reported. Further longitudinal studies are required t o assess the consequences of maternal HHV-6 infection. (C) 2000 Elsevier Sc ience B.V. All rights reserved.