Syphilis Resurgence: A Challenge for Science

A Surging Issue in the United States

Syphilis, a sexually-transmitted infection, has made a comeback, particularly in the United States. According to the latest statistics, over 171,000 cases were reported in 2021, which represents a 68% increase from 2017. The situation is particularly concerning because the number of congenital syphilis cases, which occurs when a fetus contracts the infection during pregnancy, has tripled during the same period. Despite cycles of syphilis rises and declines over the years, the underlying cause of the current resurgence is not fully understood. However, experts point to several factors such as the increase in condomless sex related to new HIV/AIDS prophylactics, illicit drug use, and the popularity of dating apps.

Treating Syphilis: A Daunting Task

Treating syphilis has always been challenging due to the fragility of its causative agent, Treponema pallidum, making it hard to detect and cultivate in laboratories. As a result, researchers’ ability to develop new diagnostics, treatments, and preventive measures such as vaccines is limited. Moreover, T. pallidum can evolve resistance to antibiotics, complicating the search for effective treatments. If left untreated, the infection can cause permanent damage to various organs and be life-threatening. Congenital cases can result in birth defects, stillbirth, and premature death.

New Techniques to Grow the Bacteria

The main obstacle in syphilis research has been the inability to grow the delicate bacteria that causes it in the laboratory. In 2018, scientists at the University of Texas Health Science Center in Houston developed a novel technique for long-term cultivation of T. pallidum using rabbit skin cells, which enhanced the conditions by adding more nutrients to the mix. Researchers found that the bacteria could grow for more than three years and retain their structure, ability to move, multiply, and cause infection. In 2021, scientists used this technique to identify an antibiotic known as linezolid as a potential syphilis treatment. This discovery is especially important because some people are allergic to penicillin, which has been traditionally used as the first line of defense against syphilis.

Diagnosis and Vaccination: Moving Forward

Diagnostic tests for syphilis require improvement because those currently in use cannot differentiate active versus previous infections. Antibody levels do not drop after treatment in about a quarter of people infected with syphilis, making it difficult for doctors to distinguish between new and old infections. Researchers are developing a test that directly detects syphilis-causing bacteria through its DNA or proteins. In February 2022, a $2 million grant from Open Philanthropy was awarded to Caroline Cameron to help develop such a test, which looks for proteins in patient samples including urine and plasma. Although progress has been slow, developing a vaccine remains the best solution for eliminating the disease.

Challenges and Potential Solutions

The bacterium’s proteins responsible for spreading the disease within the body and between people have been identified, and a potential vaccine that targets these proteins has been tested in rabbits. Although the vaccine failed to provide complete protection against infection, it did reduce transmission or spread. While the results could be stronger, the study is “very exciting,” according to Christopher Kenyon, a professor at the Institute of Tropical Medicine in Antwerp, Belgium. Many experts agree that a vaccine has the potential to eliminate syphilis altogether, preventing the development of antibiotic resistance in this bacterial pathogen.

Prevention and Treatment: A Combined Effort

Preventing syphilis requires practicing safe sex, including the use of condoms. People who are sexually active, particularly men who have sex with men, are encouraged to get tested regularly. If syphilis is detected early, it can be treated with antibiotics, usually penicillin. However, for those who are allergic to penicillin, other antibiotics can be used. A proper diagnosis is crucial to determine the most appropriate treatment.

Controversy over Antibiotic Use

The use of antibiotics to prevent syphilis, specifically the antibiotic doxycycline, has been a topic of controversy. A clinical trial in 2019 tested doxycycline post-exposure prophylaxis (PEP) in men who have sex with men and were either HIV-positive or taking medication to prevent infection. The preliminary results showed that doxycycline PEP was effective in preventing syphilis when taken within three days of condomless sex. However, some researchers worry about potential antibiotic resistance that may limit treatment options for other conditions addressed with doxycycline, such as skin infections and bacterial pneumonia.

Conclusion: A Challenge for Science and Society

Syphilis has a long history as a sexually transmitted infection, and its resurgence is a major challenge for public health experts and scientists worldwide. Despite advances in research, diagnostic, and treatment techniques, syphilis continues to be a threat to people’s health, particularly high-risk populations. Combining efforts to practice safe sex, regular testing, and prompt treatment with ongoing research, development, and dissemination of vaccines, diagnostic tools, and effective treatments is crucial to eliminate this disease. While controversies and obstacles remain, the fight against syphilis must continue as a matter of global health and social justice.