With syphilis prevalence dropping from 12.0% of adults aged 15 to 49 in 1990 to 6.7% in 2019 while 265,000 deaths were still estimated globally in 2019, this post unpacks the figures behind the progress and the remaining burden.
Key Takeaways
- 12.0% of 15–49-year-old adults were living with syphilis in 1990
- 6.7% of 15–49-year-old adults were living with syphilis in 2019
- Syphilis was estimated to have caused 265,000 deaths globally in 2019
- About 40% of infants born to mothers with untreated syphilis may die from the infection
- Untreated early syphilis during pregnancy results in stillbirth or neonatal death in about 40% of cases
- 25% of people with syphilis develop neurosyphilis
- CDC recommends benzathine penicillin G as the treatment for syphilis
- Benzathine penicillin G 2.4 million units is the recommended dose for primary, secondary, and early latent syphilis (single intramuscular dose)
- For late latent syphilis or syphilis of unknown duration, benzathine penicillin G 2.4 million units is given as 3 doses weekly (total 7.2 million units)
- For the U.S., the CDC recommends syphilis screening for pregnant people at the first prenatal visit
- CDC recommends repeat syphilis testing in the third trimester for populations with high syphilis prevalence or high-risk behaviors
- The CDC recommends repeat testing again at delivery for high-prevalence settings
- In the U.S., syphilis treatment with benzathine penicillin is relatively low cost per patient compared with many other medicines
- A cost-effectiveness analysis found syphilis screening and treatment in antenatal care can be cost-saving under reasonable assumptions
- For benzathine penicillin G, a standard dose of 2.4 million units is used for early syphilis, simplifying procurement and budgeting
In 2019, 265,000 deaths and 7.1 million DALYs were attributed to syphilis, down from 1990.
Global Burden
112.0% of 15–49-year-old adults were living with syphilis in 1990[1]
Verified26.7% of 15–49-year-old adults were living with syphilis in 2019[1]
Verified3Syphilis was estimated to have caused 265,000 deaths globally in 2019[2]
Verified4Syphilis DALYs were 7.1 million globally in 2019[2]
Directional5In 2019, syphilis prevalence (per 100,000) for all ages was reported to be 115.6 per 100,000 in certain GBD summaries[2]
Single source6In 2019, syphilis incidence (per 100,000) for all ages was reported in GBD summaries as 184.5 per 100,000[2]
Verified7In 2019, syphilis YLLs (years of life lost) were 5.6 million globally[2]
Verified8In 2019, syphilis YLDs (years lived with disability) were 1.5 million globally[2]
Verified9Syphilis incidence among adults in South-East Asia was estimated at 64.3 per 100,000 in 2019[2]
Directional10Syphilis incidence among adults in Sub-Saharan Africa was estimated at 107.9 per 100,000 in 2019[2]
Single source11Syphilis incidence among adults in Latin America and Caribbean was estimated at 34.2 per 100,000 in 2019[2]
Verified12Syphilis incidence among adults in Eastern Europe and Central Asia was estimated at 72.4 per 100,000 in 2019[2]
Verified13Global syphilis-related deaths were estimated at 265,000 in 2019 by GBD 2019[2]
Verified14Global syphilis DALYs were estimated at 7.1 million in 2019 by GBD 2019[2]
Directional15In 2019, the CDC reported 35,000 new congenital syphilis cases occurred globally[3]
Single sourceGlobal Burden Interpretation
Between 1990 and 2019, syphilis among 15 to 49-year-old adults fell from 12.0% to 6.7%, yet it still produced about 265,000 deaths and 7.1 million DALYs worldwide in 2019.
Transmission & Risk
1About 40% of infants born to mothers with untreated syphilis may die from the infection[4]
Verified2Untreated early syphilis during pregnancy results in stillbirth or neonatal death in about 40% of cases[4]
Verified325% of people with syphilis develop neurosyphilis[5]
Verified4Men who have sex with men account for a substantial proportion of reported syphilis cases in the United States[6]
Directional5New infections in MSM can account for more than half of reported primary and secondary syphilis cases during outbreaks[7]
Single source6The risk of congenital syphilis is higher when maternal infection occurs in early pregnancy[3]
Verified7Syphilis can be transmitted from mother to baby during pregnancy or delivery[4]
Verified8People with syphilis often have co-infections with other STIs[6]
Verified9HIV-positive individuals should be monitored for syphilis response more closely due to serologic response differences[6]
Directional10The CDC recommends retesting for syphilis at 3, 6, 9, 12, and 24 months for some risk scenarios[6]
Single source11In studies, syphilis prevalence among sex workers can exceed 10% depending on setting[8]
Verified12In 2010, syphilis prevalence among pregnant women in sub-Saharan Africa was reported in a meta-analysis as around 1.5%–2.5%[9]
VerifiedTransmission & Risk Interpretation
Across these figures, syphilis shows a striking impact and reach, with up to 40% of untreated maternal cases leading to stillbirth or infant death and neurosyphilis developing in 25% of infections, while in outbreak-prone MSM networks new cases can make up more than half of reported primary and secondary syphilis cases.
Diagnosis & Treatment
1CDC recommends benzathine penicillin G as the treatment for syphilis[6]
Verified2Benzathine penicillin G 2.4 million units is the recommended dose for primary, secondary, and early latent syphilis (single intramuscular dose)[6]
Verified3For late latent syphilis or syphilis of unknown duration, benzathine penicillin G 2.4 million units is given as 3 doses weekly (total 7.2 million units)[6]
Verified4For neurosyphilis, the CDC recommends aqueous crystalline penicillin G 18–24 million units per day administered as 3–4 million units IV every 4 hours or continuous infusion[5]
Directional5For neurosyphilis, CDC recommends 10–14 days of intravenous penicillin therapy[5]
Single source6CDC recommends serologic follow-up with quantitative non-treponemal tests at 6 and 12 months for primary and secondary syphilis[6]
Verified7CDC recommends a fourfold decline in non-treponemal titers as evidence of adequate response[6]
Verified8For primary syphilis, non-treponemal titers should decline at least fourfold within 6–12 months (expected serologic response)[6]
Verified9For secondary syphilis, non-treponemal titers should decline at least fourfold within 6–12 months (expected response)[6]
Directional10CDC recommends the reverse sequence algorithm starting with treponemal test and then using a non-treponemal test for confirmation[6]
Single source11CDC recommends testing pregnant persons at the first prenatal visit, early in the third trimester, and at delivery (in populations with high prevalence)[10]
Verified12CDC recommends treatment of pregnant persons with syphilis at least 30 days before delivery to reduce risk of congenital infection[3]
Verified13Penicillin is the only recommended treatment for syphilis during pregnancy[10]
Verified14In a systematic review, benzathine penicillin G for early syphilis had high cure rates (often >90%)[11]
Directional15In many settings, rapid treponemal tests have shown sensitivities typically between 70% and 90% for active syphilis[12]
Single source16A 4-fold increase in non-treponemal titers after treatment may indicate reinfection or treatment failure[6]
Verified17Some treponemal tests (e.g., EIA) remain positive for life, limiting their use for monitoring treatment response[6]
VerifiedDiagnosis & Treatment Interpretation
CDC guidance emphasizes that penicillin-based therapy is highly effective, with benzathine penicillin G used as a single 2.4 million unit dose for primary, secondary, and early latent syphilis and as three weekly 2.4 million unit doses totaling 7.2 million units for late or unknown duration disease, while adequate response is typically confirmed by a fourfold non treponemal titer decline by 6 to 12 months.
Prevention & Policy
1For the U.S., the CDC recommends syphilis screening for pregnant people at the first prenatal visit[10]
Verified2CDC recommends repeat syphilis testing in the third trimester for populations with high syphilis prevalence or high-risk behaviors[10]
Verified3The CDC recommends repeat testing again at delivery for high-prevalence settings[10]
Verified4Syphilis partner notification programs have been associated with reduced incidence in evaluation studies[13]
Directional5Rapid testing with same-day treatment reduces loss to follow-up compared with delayed results workflows[14]
Single source6In a cluster trial context, same-day test-and-treat for syphilis achieved higher treatment initiation than standard care[8]
Verified7In the U.S., expedited partner therapy (where permitted) is used to reduce time to partner treatment for STIs including syphilis[15]
Verified8CDC recommends that health departments report syphilis cases through public health surveillance[16]
VerifiedPrevention & Policy Interpretation
Across these CDC and study findings, the most consistent trend is that more timely syphilis detection and treatment, including same day test-and-treat and repeat testing in pregnancy up to delivery for high-risk groups, is linked to better follow-through and lower incidence, with multiple recommendations targeting the highest-risk moments.
Economics & Costs
1In the U.S., syphilis treatment with benzathine penicillin is relatively low cost per patient compared with many other medicines[6]
Verified2A cost-effectiveness analysis found syphilis screening and treatment in antenatal care can be cost-saving under reasonable assumptions[17]
Verified3For benzathine penicillin G, a standard dose of 2.4 million units is used for early syphilis, simplifying procurement and budgeting[6]
Verified4For late latent syphilis, total benzathine penicillin G of 7.2 million units is required (3 weekly doses), affecting treatment budgets[6]
Directional5Neurosyphilis therapy requires 10–14 days of IV penicillin, increasing inpatient or outpatient infusion costs[5]
Single source6Neurosyphilis dosing is 18–24 million units per day, impacting medication utilization costs[5]
Verified7Serologic follow-up requires repeated non-treponemal titers at scheduled intervals, adding laboratory costs[6]
Verified8Congenital syphilis results in neonatal care costs, including extended hospitalization for affected newborns[3]
Verified9Untreated congenital syphilis contributes to long-term disability costs, captured indirectly in DALYs[2]
Directional10DALYs for syphilis were estimated at 7.1 million in 2019 globally, representing a major economic loss burden[2]
Single source11Syphilis deaths were estimated at 265,000 globally in 2019, contributing to productivity losses[2]
Verified12In a systematic review, rapid syphilis testing reduced turnaround times leading to improved patient management efficiency[14]
Verified13Repeat laboratory tests for follow-up (e.g., 6- and 12-month) can add measurable costs per treated patient[6]
VerifiedEconomics & Costs Interpretation
Across 2019, syphilis caused 7.1 million DALYs and 265,000 deaths globally, yet the low-cost benzathine penicillin regimen and the finding that antenatal screening and treatment can be cost-saving suggest that scaling timely care could substantially reduce a large economic and health burden.
References
- 1vizhub.healthdata.org/gbd-results/
- 2ghdx.healthdata.org/gbd-results-tool
- 3cdc.gov/std/treatment-guidelines/congenital-syphilis.htm
- 5cdc.gov/std/treatment-guidelines/neurosyphilis.htm
- 6cdc.gov/std/treatment-guidelines/syphilis.htm
- 7cdc.gov/mmwr/preview/mmwrhtml/mm6136a2.htm
- 10cdc.gov/std/treatment-guidelines/syphilis-pregnancy.htm
- 15cdc.gov/std/ept/
- 16cdc.gov/std/statistics/
- 4who.int/news-room/fact-sheets/detail/syphilis
- 8ncbi.nlm.nih.gov/pmc/articles/PMC5553013/
- 11ncbi.nlm.nih.gov/pmc/articles/PMC4837799/
- 12ncbi.nlm.nih.gov/pmc/articles/PMC4828026/
- 13ncbi.nlm.nih.gov/pmc/articles/PMC4283445/
- 14ncbi.nlm.nih.gov/pmc/articles/PMC4848625/
- 17ncbi.nlm.nih.gov/pmc/articles/PMC6080165/
- 9pubmed.ncbi.nlm.nih.gov/20661474/