Syphilis makes a comeback

“Doctors were yesterday warned of an alarming rise in syphilis in the UK”, The Sun reports.

The Independent covered the same story, saying that specialists from the Centers for Disease Control and Prevention in the US have said that cases of the disease are soaring in high-income countries. It adds that the number of cases in the UK jumped from 307 in 1997 to 3,702 in 2006, “an increase of 1,200 per cent”.

The Times reports that, despite being nearly wiped out in the developed world a decade ago, the disease has had a resurgence, “in part driven by increases in cases among men who have sex with men [and] more recent increases among heterosexual people”. Most of the newspapers report that the specialists have warned that doctors now lack experience of syphilis and need training to deal with the disease.

The stories are based on a review in which the authors carried out a comprehensive overview of the published literature on the transmission and rates of syphilis in Western Europe and the USA between 2000 and 2007. The authors discuss various explanations for changing rates of the disease and give an expert opinion on the current standards in diagnosis and treatment.

The journal that this paper was published in is prestigious and the experience and knowledge and of the authors is clear; this suggests that this is a reliable review and that cases of infectious syphilis are increasing.

Where did the story come from?

The review was written by Dr Kevin Fenton from the National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention at the Centers for Disease Control and Prevention in Atlanta and colleagues from around the US. The study was supported by a grant from the National Institute of Health and the National Institute of Allergy and Infectious Diseases. The review was published in The Lancet Infectious Diseases, a peer-reviewed medical journal.

What kind of scientific study was this?

The authors of this non-systematic narrative review searched two databases for all research articles published between 2000 and 2007 on infectious syphilis. Earlier publications and books that were commonly referenced and highly regarded were also included.

Syphilis is a sexually transmitted infection (STI) caused by the spiral-shaped bacterium (spirochaete): treponema pallidum. The infection has two stages, primary and secondary. During the primary stage lesions (sores and rash) appear on the skin. These are very infectious and most cases of venereal syphilis are contracted through direct sexual contact with a person who has active syphilis. About 50% of people in direct sexual contact with someone who has active infection will develop syphilis. Infected mothers can also pass on syphilis to their unborn babies through the placenta. Transmission by other means, such as non-sexual close contact with an infected person and accidental infection by blood from needles, is less common.

Primary syphilis refers to the first infection, which usually shows as a lump or ulcer at the site of contact two to six weeks after infection. Secondary syphilis refers to later symptoms and signs of the disease, which usually follow the healing of the first infection by six months or more. This secondary infection results from the multiplication and spread of the bacteria throughout the body and can be expected to show different rates in the community than the primary infection, depending on how successful treatment has been. Treatment with penicillin has been available for 50 years and is effective at eliminating the bacterium.

What were the results of the study?

Among the facts that are reported in this review, the researchers mention that the rates of infectious syphilis fell to their lowest levels in many European Union countries by the early 1990s.

By 1995, all reporting European countries (except Germany) had fewer than 300 recorded cases of infectious syphilis. However, this figure steadily rose across Europe until, around 2000, various countries began reporting increases. Belgium reported a more than three-fold increase in cases between 2000 and 2002, and cases in Austria steadily increased from a low point of 124 in 1993 to 420 in 2002. Current rates of syphilis in the UK are not given in this paper.

The researchers said there have been ‘alarming recent trends’ in relatively wealthy parts of the globe with ‘huge’ increases in urban centres such as London, predominantly among populations of men who have sex with men. These increases were initially observed in cities and later in suburban and rural settings.

They provided maps of the rates of primary and secondary syphilis in different US states in 2003 and the trends observed between 1963 and 2003. The researchers were particularly interested in the rise and fall of the rates of syphilis infection over time. Two explanations seemed likely for this pattern: either syphilis rates were varying as a result of interactions between the syphilis bug and a population’s immunity, or alternatively, syphilis epidemics were part of a cycle determined by the infectious nature of the disease.

To look at this further they produced mathematical models using data from different time periods. They found that the overall number of patients with primary and secondary syphilis showed a different pattern in the populations who remained untreated, compared to those where 30% of cases were treated. These rates also varied depending on whether the population modelled had either five or forty sexual partners per year. The results from these models suggested that current incidence rates are not part of a cycle due to the infectious nature of the disease, but are the result of changing immunity (such as occurs with HIV/AIDS).

What interpretations did the researchers draw from these results?

The researchers call for concerted public health action. They say that the recent increase in syphilis among men who have sex with men and some high-risk heterosexual couples “raises cause for concern, and demands renewed vigilance among, and training of, healthcare professionals”.

They also ask for new diagnostic tools, social network approaches and new initiatives in prevention, monitoring and evaluation treatment for this disease.

What does the NHS Knowledge Service make of this study?

This comprehensive overview contains sections that describe the biology, history, diagnosis, treatment and control of syphilis. It also summarises what is known about the transmission of the disease and what influences this transmission.

Current rates of syphilis in the UK are not given in this paper. However, they can be expected to follow the trends in other European countries. Other sources quoted by The Independent suggest that UK rates have jumped from 307 cases in 1997 to 3,702 in 2006, an increase of 1,200 per cent.

It is not clear how the references were selected for inclusion or assessed for quality, but the experience and knowledge of the authors is clear and suggests that this is a reliable review.