Human herpevirus-6 infection in pregnant and nonpregnant women

Human herpesvirus-6 (HHV-6) commonly infects infants and is associated with roseola infantum. HHV-6 previously has been shown to be shed in the female genital tract, especially in women in sexually-transmitted disease clinics (Leach et al., J Infect Dis, 1994;169:1281-3). Little information is available regarding infection and viral shedding in other groups of women. We present cross-sectional laboratory data for groups of nonpregnant and pregnant women. Methods: Women age 18-45 attending a university family planning clinic (nonpregnant) and two obstetrics clinics (pregnant, first trimester) in San Antonio were provided informed consent and enrolled between October 1995 and May 1998. A questionnaire, blood and vaginal swab were collected from each participant. Plasma was tested for HHV-6 IgG antibodies using a standard immunofluorescence assay (IFA). Lysed material from vaginal swabs was tested for HHV-6 DNA by polymerase chain reaction (PCR) with product detection by ELISA using a digoxigenin-labeled probe. All PCR-positive samples were confirmed by repeat PCR followed by Southern analysis. PCR-positive samples were subtyped using an established method. Results: A total of 569 women (224 nonpregnant, 345 pregnant) were enrolled. The majority (83%) were Hispanic. All subjects were HHV-6 antibody positive. Geometric mean titers against HHV-6 differed among pregnant (1:88) and nonpregnant (1:147) women. A higher proportion of nonpregnant vs. pregnant women had antibody titers ≥1:320 (32.9% vs. 17.9%, p<0.05). Low rates of HHV-6 shedding in the genital tract were observed for both groups (pregnant, 5/297 [1.7%]; nonpregnant, 5/214 [2.3%]). Of 9 samples subtyped, 4 (44%) were subtype A. Conclusions: These groups of pregnant and nonpregnant women were universally infected with HHV-6 but shed the virus at low rates in the genital tract. HHV-6 subtype A was noted more commonly than previous studies in adults. Followup of pregnant women and their offspring will be important for identifying sources for transmission in the neonate and infant.