The alarming surge in HIV and syphilis infections among MSM in the United States highlights a growing public health crisis, driven by biological, behavioral, and systemic factors.

The rapid spread of HIV and syphilis among men who have sex with men (MSM) in the United States is driven by a complex interplay of behavioral, biological, and systemic factors. According to the CDC, MSM accounted for nearly 45% of all male primary and secondary syphilis cases in 2022, and 36% of those MSM also had HIV. This co-infection is not coincidental-syphilis sores create direct entry points for HIV, significantly increasing the risk of transmission during sexual contact. A systematic review published in Sexually Transmitted Infections found that syphilis infection more than doubles the risk of acquiring HIV, especially in high-risk populations like MSM.

Biologically, syphilis and HIV reinforce each other’s transmission. Syphilis causes ulcers and inflammation that compromise mucosal barriers, making it easier for HIV to enter the bloodstream. Conversely, HIV weakens the immune system, which can make syphilis harder to detect and treat, especially in its latent stages. This synergy not only accelerates the spread of both infections but also complicates treatment outcomes. The CDC emphasizes that MSM with untreated or advanced HIV may experience more severe syphilis symptoms and slower recovery, further perpetuating the cycle of transmission.

Behavioral and social dynamics also play a critical role. High rates of partner change, condomless sex, and use of dating apps among some MSM subgroups increase exposure risk. Moreover, stigma and discrimination can discourage regular testing and open conversations about sexual health.

A JAMA Network review found that routine syphilis screening every three months, as opposed to annually, significantly improved detection rates among MSM, especially those living with HIV. Yet, access to such frequent testing remains uneven across communities, particularly for those without insurance or in underserved areas.

Finally, public health infrastructure and awareness campaigns have struggled to keep pace with the evolving epidemic. While tools like PrEP and Doxy-PEP offer promising prevention strategies, uptake remains limited.

The American Academy of HIV Medicine notes that over 50% of MSM with syphilis are also HIV-positive, underscoring the need for integrated STI and HIV prevention services. Addressing this crisis requires not only biomedical solutions but also culturally competent outreach, expanded testing access, and destigmatization efforts that empower MSM to take control of their sexual health.

Preventing the continued rise of HIV and syphilis among MSM in the U.S. requires a multi-pronged approach that combines biomedical tools, behavioral interventions, and systemic reforms. One of the most effective strategies is routine and frequent STI screening, especially for high-risk individuals. The CDC recommends that sexually active MSM, particularly those with HIV or on PrEP, get tested for syphilis every 3 to 6 months. Early detection allows for timely treatment, which not only prevents complications but also reduces the likelihood of further transmission. Clinics and public health programs must expand access to affordable, stigma-free testing services, especially in underserved communities.

Another critical preventive measure is consistent condom use during all forms of sexual activity. Condoms remain a frontline defense against syphilis and HIV by reducing direct contact with infectious sores and bodily fluids. However, because syphilis sores can appear in areas not covered by condoms, additional biomedical tools like Doxy-PEP (post-exposure prophylaxis with doxycycline) are gaining traction. Studies show that taking doxycycline within 72 hours of condomless sex can reduce the risk of acquiring syphilis, gonorrhea, and chlamydia by up to two-thirds. This approach is especially effective among MSM and is being integrated into STI prevention programs in several U.S. cities.

Pre-exposure prophylaxis (PrEP) for HIV is another game-changing tool. PrEP involves taking a daily pill that significantly lowers the risk of contracting HIV. When combined with regular STI screening and Doxy-PEP, PrEP forms part of a comprehensive prevention toolkit.

However, uptake remains uneven due to barriers like cost, lack of awareness, and medical mistrust. Public health campaigns must work to normalize these preventive options, especially among younger MSM and communities of color who are disproportionately affected.

Finally, addressing stigma and improving sexual health education are essential to long-term prevention. Many MSM avoid testing or treatment due to fear of judgment or discrimination. Culturally competent outreach, peer-led education, and inclusive healthcare environments can help dismantle these barriers. Integrating HIV and STI services, so individuals can access testing, counseling, and treatment in one place, also improves outcomes. By combining science, empathy, and equity, we can slow the spread of these infections and empower MSM to protect their health and their communities.