Syphilis in HIV-infected mothers and infants: results from the NICHD/HPTN 040 study

Untreated syphilis during pregnancy is associated with spontaneous abortion, stillbirth, prematurity and infant mortality. Syphilis may facilitate HIV transmission, which is especially concerning in low- and middle-income countries where both diseases are common.

We performed an analysis of data available from NICHD/HPTN 040 (P1043), a study focused on the prevention of intrapartum HIV transmission to 1684 infants born to 1664 untreated HIV-infected women. This analysis evaluates risk factors and outcomes associated with a syphilis diagnosis in this cohort of HIV-infected women and their infants.

Approximately, 10% of women (n=171) enrolled had serological evidence of syphilis without adequate treatment documented and 1.4% infants (n=24) were dually HIV and syphilis infected. Multivariate logistic analysis showed that compared with HIV-infected women, co-infected women were significantly more likely to self-identify as non-white (adjusted odds ratio [AOR] 2.5, 95% CI: 1.5-4.2), to consume alcohol during pregnancy (AOR 1.5, 95% CI: 1.1-2.1) and to transmit HIV to their infants (AOR 2.1, 95% CI: 1.3-3.4), with 88% of HIV infections being acquired in utero. As compared with HIV-infected or HIV-exposed infants, co-infected infants were significantly more likely to be born to mothers with venereal disease research laboratory titers≥1:16 (AOR 3, 95% CI: 1.1-8.2) and higher viral loads (AOR 1.5, 95% CI: 1.1-1.9). Of 6 newborns with symptomatic syphilis, 2 expired shortly after birth, and 2 were HIV-infected.

Syphilis continues to be a common co-infection in HIV-infected women and can facilitate in utero transmission of HIV to infants. Most infants are asymptomatic at birth, but those with symptoms have high mortality rates.