Big decline in syphilis seen after introduction of doxyPEP

News brief

Illustration of syphilis bacteria — quantic69 / iStock

Syphilis diagnoses declined dramatically in the Seattle area following implementation of doxycycline post-exposure prophylaxis (doxyPEP), researchers reported last week in Clinical Infectious Diseases.

Using public health surveillance data from January 2017 through June 2025, researchers from the University of Washington and Public Health–Seattle & King County assessed monthly syphilis diagnoses overall and by gender before and after doxyPEP implementation in March 2023. Since it was introduced in King County, use of doxyPEP, which involves taking a dose of the antibiotic doxycycline within 72 hours of unprotected sex, has become common among men who have sex with men (MSM) and transgender women who have sex with men, the researchers note. Those are the two groups for whom the intervention is recommended.

Randomized clinical trials have found that doxyPEP reduces the risk of incident syphilis in MSM and transgender women by 73% to 80%, and a real-world study conducted in San Francisco found syphilis cases have been cut in half in those populations since implementation. Based on those findings, the study authors hypothesized they would observe similar decreases in these groups.

No reduction in congenital syphilis

Compared with the pre-implementation period, the post-implementation period saw an absolute reduction of 3,031 syphilis cases overall and a relative reduction of 52.3%. Among cisgender men and women, syphilis cases fell by 53.1% and 46.9%, respectively, while transgender and nonbinary people saw 33.1% fewer syphilis cases.

But the number of pregnant women diagnosed as having syphilis rose from 13 to 48, and the number of cases of congenital syphilis—when the infection is passed from mother to child—increased from 0 to 23.

The authors note that since doxyPEP isn’t routinely recommended or prescribed to cisgender women, the observed decline in syphilis cases among those patients likely reflects an “indirect effect” of decreased transmission through shared sexual networks. Although pregnant women do not appear to be benefitting from that effect, they say the overall decline in syphilis cases has allowed public health officials to focus more intently on these women, which they hope will ultimately lead to reductions in congenital syphilis.

Tpoxx should no longer be used to treat mpox, European drug regulators say

News brief

Chris Dall, MA

Mpox under a microscope — NIAID / Flickr cc

The European Medicines Agency (EMA) is recommending that the antiviral drug tecovirimat (Tpoxx) no longer be used for treating mpox.

The recommendation, made by the EMA’s Committee for Medicinal Products for Human Use, is based on four studies that have found that Tpoxx was no better than a placebo to heal active mpox lesions, relieve pain, or help clear the virus faster.

Tpoxx was authorized to treat mpox by the EMA in November 2021. But EMA officials noted that the authorization for mpox was based on an animal model of mpox infections, since the virus was not circulating widely enough in people at the time to conduct human studies.

“The animal data demonstrated antiviral activity and a survival benefit when treatment was started early and a reduced efficacy if treatment was initiated later after exposure to the virus,” they said in a news release.

That was before clade 2 mpox outbreaks began in 2022. Those outbreaks, which the led the World Health Organization (WHO) to declare mpox a Public Health Emergency of International Concern (PHEIC), enabling drugmaker SIGA Technologies to conduct efficacy studies in people. The WHO declared a second PHEIC in 2024 over clade 1 outbreaks.

The EMA says the recommendation doesn’t apply to authorized use of Tpoxx for smallpox, cowpox, and complications from smallpox vaccines.

Most current mpox cases are in Africa

Meanwhile, the WHO said in an outbreak update last week that 1,184 confirmed mpox cases and four deaths were reported in 46 countries across all WHO regions in February. Of these cases, 58.6% were reported in Africa.

The countries reporting the most cases over the past six weeks are Madagascar, the Democratic Republic of the Congo, Kenya, Burundi, and Liberia.

The WHO said all clades continue to circulate, and transmission of the virus continues mostly within sexual networks, followed by household transmission. All age-groups in some historically endemic areas are being affected.

“Unless mpox outbreaks are rapidly contained and human-to-human transmission is interrupted, there is a risk of sustained community transmission in all settings,” the WHO said.

Ebola virus may linger in breast milk for weeks after recovery

News brief

Laine Bergeson

The Ebola virus (EBOV) might persist in breast milk for weeks after maternal recovery, according to a letter in the New England Journal of Medicine. The findings raise the possibility of post-illness transmission to infants, even as blood tests and other measures of viral load are negative.

The report describes a 23-year-old woman in the Democratic Republic of the Congo (DRC) who contracted EBOV during pregnancy in 2019. She received monoclonal antibody therapy at an Ebola treatment unit in Butembo, DRC, and was discharged after three negative reverse-transcriptase–polymerase-chain-reaction blood tests for EBOV. At 42 weeks gestation, she delivered a healthy infant with no evidence of EBOV infection in maternal blood, amniotic fluid, vaginal secretions, or the newborn.

Ebola still detectable in breast milk at 14 weeks

But EBOV RNA persisted in the placenta and breast milk. To reduce the infant’s risk of contracting the disease, researchers kept the mother from breastfeeding and gave a prophylactic (preventive) monoclonal antibody to the newborn. During follow-up, the infant exhibited no signs of infection.

Ongoing testing showed that the mother’s blood remained negative, but viral RNA was still detectable in breast milk at 14 weeks after illness onset. To protect the newborn from transmission, clinicians used the drug bromocriptine to suppress lactation.

While the authors call for further studies and the use of viral culture to better assess infection risk, the findings suggest the potential for mother-to-child transmission while breastfeeding. Current World Health Organization guidance recommends that Ebola survivors avoid breastfeeding until viral clearance is confirmed.