Syphilis: An Old Disease With Very Modern Consequences

By Nathan Foster

Edited by Glenn T Johnston

If you think syphilis is a relic of dusty history books, think again. This centuries-old infection, caused by the bacterium Treponema pallidum, is quietly climbing back into American cities, including Baltimore. And while it starts small, often with a painless sore most people never even notice, untreated syphilis can unfold into a years-long health crisis.

In its early stages, the infection might show up as a faint rash or swollen lymph nodes, easy to mistake for stress, allergies, or just “not feeling great.” Then, without warning, symptoms disappear. But the disease doesn’t. In the latent stage, syphilis hides, waiting. Left untreated long enough, it can resurface as a devastating attack on the heart, brain, nerves, and other organs. Globally, millions face this risk every year, especially in areas with limited access to healthcare. And because pregnant individuals can pass it to their babies, syphilis isn’t just a personal health issue, it’s a community one.

Poster reminding people to get checked for syphilis by their doctor. By the NYC Board of Health at Staten Island, a maritime community in the 1900s. (Library of Congress)

A Disease With a History

Syphilis has been affecting humanity since the late 1400s, when it rapidly spread through Europe with a surprising ferocity. Early “treatments” were often worse than the disease itself: mercury rubs, toxic metals, and painful regimens that offered little relief. It wasn’t until the early 1900s that the first effective drug appeared, and by the 1940s, penicillin finally turned syphilis into a curable infection. You’d think that would be the end of the story. But public health victories don’t stay victories unless we maintain our vigilance. Around the world, where access to healthcare is limited or STI stigma remains strong, syphilis continues to circulate. And as we’ve learned repeatedly, no community is immune when prevention efforts slip.

Early Ties to the Maritime World

Syphilis has a profound historical connection to seaports and maritime activities, primarily because sailors, explorers, merchants, and naval personnel served as key sources for its transmission. Ports acted as natural hubs: ships docked, crews went ashore seeking companionship (often with sex workers), and then carried the infection to new destinations along trade routes. This pattern repeated across centuries, from the time the disease appeared in Europe to its subsequent global distribution.

During the Age of Sail, venereal diseases (syphilis and gonorrhea) were common hazards for seafarers. Ships’ surgeons routinely treated them, observing they were almost always contracted ashore rather than at sea. Experienced British naval surgeon John Moyle observed in his book Sea-Chirurgion, in 1693, that syphilis, "albeit it is not usually got aboard a ship; yet it often falls to the Sea-Surgeons' Lot, to Cure it on board."

Syphilis and other venereal diseases were longstanding occupational hazards for sailors and port workers, typically contracted during shore leave in port cities. Before the widespread availability of antibiotics, before the 1940s, these infections caused substantial lost working time, as shown in military and naval records, which reflect conditions faced by civilian maritime workers as well.”

During World War I (1917–1918), the U.S. military, including the Navy, recorded 358,000 admissions for VDs (a rate of 87 per 1,000 personnel) and lost a total of 6.8 million duty days to these conditions. Syphilis cases often required treatment lasting six months or more, resulting in over 180 lost days per case, while gonorrhea typically sidelined individuals for about 30 days.

In port cities like Baltimore, where sailors frequently mingled with local populations, these patterns contributed to elevated regional rates. By the mid-20th century, even after penicillin became available, syphilis continued to affect seafaring workforces. A 1960s study of the Norwegian merchant fleet found that venereal diseases accounted for 2% of all absences, equating to roughly 5,000 lost working days per year across about 25,000 seamen. In the pre-penicillin 1940s, however, syphilis recovery still commonly took up to six months. This shows how deeply syphilis affected maritime labor before modern treatment.

Baltimore’s Wake-Up Call

Between 1993 and 1995, Baltimore saw a 97% increase in syphilis cases, jumping from 179 to 352 reported cases a year. It wasn’t random. Cuts to public health funding, combined with rising crack and cocaine use, contributed to a sharp increase in cases. Outreach teams had fewer resources. Clinics struggled to keep up. Partner-tracing efforts that once stopped outbreaks early suddenly faltered. The result was a surge in reported cases.

Syphilis can stay silent for years with no outward symptoms. When testing and public health surveillance programs are unable to maintain their vigilance, infections spread under the radar. By the time it is recognized, a city may already be deep in an outbreak. Baltimore’s 1990s experience is a reminder that this disease is not “over.” It’s waiting for a time when surveillance and treatment resources are shifted elsewhere.

If Syphilis Returned Today, Who Would Feel It?

As a gateway for international seafarers and cruise passengers, the Port of Baltimore connects the city to global travel patterns. Infections circulating elsewhere can reach Baltimore through ordinary human contact. When infections rise elsewhere, they can rise here as well. Ports serve as hubs of human movement, bringing in transient people like seafarers and cruise passengers who arrive, spend time ashore, and often seek temporary companionship or intimate encounters. These brief relationships can overlap with existing local connections—where individuals already have multiple or concurrent partners—creating pathways for infections like syphilis to cross from newcomers into the broader community. Dockworkers, truckers, maritime crews, and others move within the city and between cities, states, and countries. A local outbreak can become a regional one within weeks.

Once widespread within the city, clinics would be crowded with people seeking testing and treatment. Hospitals would see an increase in neurological and cardiac complications tied to untreated infections. Pregnant patients would need urgent screening to protect their babies from congenital syphilis, a condition that can cause stillbirth, organ damage, or lifelong illness.

The state would need additional funding, expanded public health staffing, and broader education campaigns. Neighboring states would quickly feel the overflow. The Mid-Atlantic region depends heavily on Baltimore as a transportation and economic hub. What happens in Baltimore rarely stays in Baltimore.

Why This Matters Now

Syphilis isn’t just about sexual health, it’s about community health, economic stability, and public systems that keep cities running. The disease thrives when public health departments lose funding, when stigma keeps people from testing, and when communities underestimate the threat.

Baltimore has beaten syphilis back before. But history shows that the moment we stop paying attention is the moment we open the door to its undetected return.