Odds of getting syphilis
In this section, we’ll talk about the odds of getting syphilis.
Since many syphilis cases are asymptomatic and the complications of untreated syphilis can be quite bad, the odds of getting syphilis are very important.
Doctors rely quite a bit on the odds of transmission in making an early diagnosis and initiating treatment.
Here we summarize important information about the prevalence, incidence, and transmission of syphilis.
We’ve separated the information based on gender, age, sexual orientation, and transmission routes.
We’ve also collected data about transmission rates during protected and unprotected sex and for one-time and multiple sexual acts.
Let’s dive in!
Syphilis prevalence in the U.S. regardless of gender
In 2001, the number of reported cases of primary and secondary syphilis was the lowest in the history of reporting this disease (since 1941); 2.1 cases per 100,000 population. The number of cases has been increasing since then. It increased by 39% from 2014 to 2018 and by 13.3% from 2017 to 2018.
| Total number of syphilis cases (Primary and secondary) | Number of syphilis cases per 100,000 population (Primary and secondary) |
|---|
| 2000 | 31,168 | 2.1 |
| 2010 | 45,844 | 4.5 |
| 2018 | 115,045 | 10.8 |
Syphilis prevalence in U.S. by gender
As we can see from the table, the number of cases for both genders are going up, but a majority of syphilis cases are in males.
| Incidence in the U.S | Females (per 100,000 population) | Males (per 100,000 population) |
|---|
| 2000 | 2,445 (1.7) | 3,532 (2.6) |
| 2010 | 1,780 (1.1) | 11,981 (7.9) |
| 2018 | 5,047 (3) | 30,364 (18.7) |
Syphilis prevalence in New York City
Since we live and practice in NYC, we like to know what’s going on here. The number of syphilis cases has been increasing for both genders, and more so for females: 147% during 2015–2016.
The neighborhoods with the highest rates of primary and secondary syphilis were all in Manhattan: Chelsea, Central Harlem, and Washington Heights.
| Incidence in the U.S | Females (per 100,000 population) | Males (per 100,000 population) |
|---|
| 2009 | 48 (1.10) | 1008 (25.23) |
| 2018 | 171 (1.7) | 2,483 (25.8) |
Syphilis prevalence by age
As we can see in the table, the number of cases is highest in younger people, for multiple reasons:
- Period of exploration in relationships and sexual practices
- Inability to get tested and treated because of inability to pay
- Conflict between school, work, and clinic hours
- Social stigma and embarrassment
In 2017–2018, the rate of reported primary and secondary syphilis cases increased 14.9% among persons aged 15–19 years and 10.3% among persons aged 20–24 years.
| Number of primary and secondary syphilis cases per age group |
|---|
| 2010 |
|---|
| Age group | Females | Males |
|---|
| 15-19 | 313 | 617 |
| 20–24 | 474 | 2,429 |
| 25–29 | 322 | 2,131 |
| 30–34 | 197 | 1,597 |
| 35-39 | 140 | 1,313 |
| 40-44 | 104 | 1,448 |
| 45-54 | 176 | 1,877 |
| 55–64 | 36 | 457 |
| ≥65 | 6 | 105 |
| 2018 |
|---|
| Age group | Females | Males |
|---|
| 15-19 | 442 | 1,175 |
| 20–24 | 1,076 | 5,061 |
| 25–29 | 1,077 | 6,625 |
| 30–34 | 816 | 5,084 |
| 35-39 | 621 | 3,574 |
| 40-44 | 358 | 2,328 |
| 45-54 | 423 | 3,973 |
| 55–64 | 145 | 1,782 |
| ≥65 | 25 | 412 |
Frequently Asked Questions
In this section, our expert doctor will answer real-life patient questions about the odds of getting syphilis. Most questions are grouped together so it is easier to cover more topics.
Dr. Fuzayloff has been a practicing physician at a busy STD center in Midtown Manhattan, NYC, for over two decades.
What behavior is considered high risk and increases the chance of contracting syphilis? 
- Condom-less sex
- Multiple sex partners
- Sex while under the influence of alcohol or drugs
- The presence of another STD while you’re having sex
What factors affect the chance of getting syphilis in a relationship?
- Frequency of sex
- Type of sexual contact (oral, vaginal, rectal)
- Syphilis stage
- Use of protection
What is the chance of getting syphilis from one-time unprotected sex (assuming your partner is syphilis-positive)?
- The chance of contracting syphilis with one-time contact with a person who already has syphilis is 10% to 30%.
- It is a wide range because it depends on the location of the sore, type of contact, and duration of sex.
What is the chance of getting syphilis with multiple unprotected sexual contacts (assuming your partner is syphilis-positive)?
The chance of contracting syphilis (when your partner is syphilis-positive) from multiple sexual contacts with the same person over time is about 60%.
What is the chance of getting syphilis with one-time protected sex (assuming your partner is syphilis-positive)?
The chance of contracting syphilis through one-time protected sex with a person who has syphilis is between 0% and 26.7%. It depends on the location of the sore and whether it is covered by a condom.
How much protection does a condom provide?
Syphilis transmission happens thorough skin-to-skin contact (when a syphilis sore touches a partner’s skin). Whether transmission occurs depends on the location of the sore and whether a condom covers it at the time of contact. For that reason, protection reduces the chance of transmitting syphilis from 11% to 100%.
What explains the fact that homosexual males are diagnosed with syphilis more often?
Here are the syphilis statistics for homosexual males to be aware of:
- 54% of all syphilis cases are diagnosed in homosexual males
- Half of those patients are also infected with HIV
There are a few factors that explain this:
- Homosexual people have more sexual partners than heterosexual people do.
- There is a greater chance of abrasion of the rectum, as compared to the vagina, because the rectum is not self-lubricating and elastic.
- The rectum has more blood supply than the vagina, and that increases the chance of infection due to the accessibility to blood pathways.
What is the chance of getting latent-stage syphilis?
Syphilis is latent when a person is positive for syphilis but has no visible syphilis symptoms or signs. The chance of getting syphilis at that stage is twice less than with primary syphilis that is 15% per unprotected act and 30% in a couple across multiple sexual acts over time.
What is the chance of getting syphilis from someone with primary (sore) or secondary (rash) syphilis?
Syphilis is very contagious and transmitted via skin-to-skin contact. The chance of getting syphilis from a sore (primary syphilis) or rash (secondary syphilis) is about the same: 10%–30% per unprotected contact and 60% with multiple contacts with the same person.
For a heterosexual couple, who is at higher risk of getting syphilis?
In a heterosexual couple, females are more likely than males to get syphilis (as well as chlamydia and gonorrhea). The reason is the female genital anatomy:
- Bigger area exposed
- Greater chance of micro damage
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