Journal of the New Zealand Medical Association, 11-March-2005, Vol 118 No 1211
Is syphilis resurgent in New Zealand in the 21st century? A case series of infectious syphilis presenting to Auckland Sexual Health Service
There has been an alarming rise in the incidence of bacterial sexually transmitted infections (STI) in New Zealand in recent years. The last annual STI surveillance report produced by Environmental Science and Research Ltd (ESR) in 2003 indicated a 65.5% increase in the incidence of chlamydia and a 57% rise in the incidence of gonorrhoea since 1999.1 Infectious syphilis, however, has (until recently) remained a relative rarity, except for occasional cases in New Zealanders who have had sex overseas or in immigrants from endemic areas. In 2003, a total of 30 cases of infectious syphilis were reported to ESR: all seen at sexual health clinics.1 The majority of cases were in males (63.3%). In the first ESR quarterly report for 2004 (January to March), 10 cases have been reported, again the majority (70%) were men.
Unfortunately there is currently no way to verify whether the incidence of infectious syphilis in New Zealand is increasing. Unlike chlamydia and gonorrhoea, there is no laboratory surveillance of syphilis nor is it a notifiable disease—although individuals that refuse treatment may be referred to the medical officer of health under the Health Act of 1956.
Another complicating factor is that the symptoms and signs of primary and secondary syphilis may be very subtle (or easily confused with other conditions), and most medical practitioners in New Zealand (including sexual health physicians) have very little practical experience of the disease. Indeed, some incubating cases may never be identified due to inadvertent partial treatment with antibiotics prescribed for other conditions.
In the previous 2 and a half years (between January 2002 and September 2004), there appears to have been more cases of infectious syphilis presenting to Auckland Sexual Health Service. This article comprises clinical information about all the cases of infectious syphilis that have been identified at Auckland Sexual Health Service (ASHS) between January 2002 and September 2004. The aims of this paper are firstly, to examine risk factors for syphilis in patients presenting to ASHS and secondly, to alert medical practitioners outside sexual health when to consider the diagnosis.
Background—Auckland Sexual Health Service is the largest public sexual health clinic in New Zealand. There are four regional clinics that are located in Mangere, Henderson, Glenfield, and Auckland City Hospital. There are also two out-reach clinics. ASHS routinely collects clinical data on patients seen at all regional and out-reach clinics. The clinician seeing a particular patient assigns them with a diagnostic code on each presentation to the clinic with a new problem. Anonymous data on newly diagnosed cases of STIs (including infectious syphilis) are sent on a quarterly basis from all public sexual health clinics to ESR for surveillance purposes.
Inclusion criteria—The database at ASHS was searched to identify all cases of infectious syphilis presenting to the Service during the period from January 2002 to September 2004. The identified notes were examined to check whether the patients fulfilled the case definition for infectious syphilis, and then demographic characteristics and risk factors were identified. All patients being tested for syphilis at ASHS have an initial screening enzyme immunoassay (EIA) test. If this is positive, a rapid plasma reagin (RPR) test and a Treponema pallidum haemaglutination assay (TPHA) are performed on the same blood sample.
Infectious syphilis is considered to encompass primary, secondary, and early latent syphilis. These are the stages of infection when syphilis is easily transmitted through sexual or intimate contact with an infected individual. The incubation period for primary syphilis is 10 to 90 days (average 3 weeks) and the classic presenting sign is a painless ulcer or chancre in the anogenital area with regional lymphadenopathy. When lesions are present, the most specific and easiest means of diagnosing syphilis is by direct detection of the organism by either dark-field microscopy, or direct fluorescent antibody (DFA) testing.2 Serological tests for syphilis (STS) are less sensitive in primary syphilis than later on, as seroconversion usually takes several weeks after exposure to occur.
Secondary syphilis typically presents 2 weeks to 6 months after exposure (average 6 weeks) with systemic symptoms of malaise and a generalised rash and lymphadenopathy. There may also be other skin manifestations such as condyloma lata, alopecia, and mucous ulcers. Serological tests are 100% sensitive,2 and non-treponemal tests (such as RPR) typically have very high titres.
Early latent syphilis is often defined as consisting of a duration of infection of less than 12 months.3 About 25% of untreated individuals may experience relapse of clinical manifestations during the first year of infection but recrudescence is extremely rare after 2 years.4 After the early latent period, syphilis becomes defined as late latent and is regarded as non-infectious to sexual partners although untreated women may transmit the infection to their foetuses for much longer.5 Unfortunately many individuals with positive STS have no recall of any signs and symptoms of syphilis and unless they have a clearly documented previous negative test, it may be difficult to accurately determine the duration of infection.
First some general data pertaining to all the cases will be presented, and then some case histories will be given in more to detail to highlight common pitfalls in diagnosis.
A total of 40 cases of infectious syphilis were identified and verified as fitting the case definitions during the defined time period. That was more than twice as many cases as had been diagnosed in the preceding 4 years (19 cases). The cases ranged in age from 19 to 63, with a mean age of 34.2 years. The majority (82.5%) of cases were in males: reflecting similar trends to national data. The ethnic breakdown was as follows: 17 Europeans (42.5%), 4 New Zealand Maori (10%), 5 Indians (12.5%), 6 Pacific Islanders (15%), 5 Asian (12.5%), 2 ethnic Fijians (5%), and 1 Latin American (2.5%).
Fourteen cases presented with some sort of genital ulceration or genital lesion as well as having positive STS (one case couldn’t have a complete genital examination on initial presentation due to a phimosis). Nine (22.5% of total) of these cases were confirmed primary syphilis as the lesions tested positive for Treponema pallidum pallidum by DFA testing. Three of these cases also had positive dark-field microscopy. Enzyme immunoassay was 100% sensitive for all these 9 confirmed cases of primary syphilis but RPR (sensitivity 77.7%) and TPHA (sensitivity 66.6%) yielded some false negative results (Table 1).
Table 1 Confirmed direct fluorescent antibody (DFA)-positive cases of primary syphilis
EIA=enzyme immunoassay test; TPHA=Treponema pallidum haemaglutination assay test; RPR=rapid plasma reagin test; ND=not done.
Sensitivities of different STS for primary syphilis
Fourteen (35%) of the total cases presented with a generalised rash and were considered to be secondary syphilis. In all 14 identified cases of secondary syphilis, all of the STS were positive (EIA, TPHA and RPR) and all had high RPR titres ranging from 1:16 to 1:128.
Twelve cases had no symptoms or signs consistent with primary or secondary syphilis and were managed as early latent syphilis with respect to partner notification—because they had high RPR titres, they were recent contacts of infectious syphilis, or they had had recent documented treatment overseas with inadequate sero-reversal.
In all cases of early latent syphilis, all three STS were uniformly positive, with RPR titres ranging from 1:4 to 1:2560 (mean 304). Determining the duration of infection was difficult in some cases, as there was no previous documented syphilis serology. All cases of syphilis of unknown duration received treatment and follow-up as recommended for late latent syphilis.
The two main risk factors identified for acquisition of infectious syphilis appeared to be either: a history of sex overseas within the last 3 months or men who had sex with men (MSM). There were 19 cases (47.5%) who had a history of sex overseas and 18 cases (45%) who were MSM. There was very little overlap between these two main risk categories. The 19 people who gave a history of sex overseas within 3 months of presentation were nearly all heterosexual (68.4%). The most commonly cited country for overseas sex was Fiji, which is known to have a high prevalence of syphilis. (Table 2)
Table 2. Cases of infectious syphilis acquired overseas
*Her partner had sex in Fiji; MSM=men who have sex with men.
Out of the seven cases of infectious syphilis (33.3%) that were identified in heterosexuals without a recent history of sex overseas, three had other possible significant risk factors. One female patient, who was diagnosed on routine antenatal screening, had a male partner from Iraq. One patient was a Japanese male resident in New Zealand who had recently had unprotected sex with a casual female Japanese partner. One heterosexual male was also HIV-positive, so may have had other undisclosed risk factors. By contrast, only six cases in MSM (33.3%) gave a history of recent sex overseas.
There were two cases diagnosed in pregnant women (one mentioned above) on routine antenatal screening, both of whom were asymptomatic and both who had partners with infectious syphilis.
Only four patients in this series had HIV infection: all were male and three of the four were MSM. Three men were already known to have HIV and one was newly diagnosed but had probably acquired his infection some time before the syphilis infection.
Following are three case histories chosen to highlight how easily a diagnosis of syphilis may be missed by a health professional.
A 22-year-old Maori male presented to ASHS complaining of a lump on his penis for the previous week from which he could express pus. He had had a male sexual partner who was from South America. Examination revealed a large infected cyst on his penile shaft, which was treated with flucloxacillin. His STS were positive with a reactive EIA, reactive TPHA, and an RPR of 1:64, so he was recalled for treatment and partner notification. He had been treated 9 months previously by the Urology Service at Auckland Hospital so his old notes were requested. These confirmed that he had been treated for a paraphimosis. Examination findings at that time also included bilateral firm inguinal lymphadenopathy, which in hindsight was most likely due to early syphilis.
A 38-year-old European male sex worker (with both male and female clients) presented to ASHS with a 1-month history of fever, sweating and a rash. He had seen his GP recently within the last few days and had been prescribed antihistamines for the rash. On examination, he was noted to have a blotchy maculopapular rash on his trunk and arms with no involvement of his legs, palms or soles. There was no lymphadenopathy and genital examination was normal. He was thought initially to be possibly having an HIV seroconversion illness. HIV serology was negative but STS revealed a reactive EIA, reactive TPHA, and a reactive RPR 1:128. This case illustrates how easily the rash of secondary syphilis may be confused with other diagnoses.
A 41-year-old European male attended ASHS requesting an HIV test. He had been diagnosed as having pytariasis rosea 5 days earlier by his GP. His only genital symptoms were two red ‘blotches’ on his penis that were visible during erection. He had had a recent sore under his tongue that had been treated as oral candidiasis by his GP and had resolved. He had a regular male partner and disclosed having had unprotected anal and oral sex with a casual male partner 4 months prior to his presentation. Genital examination was unremarkable and there was no lymphadenopathy noted. His oral cavity was normal to inspection. He had a ‘typical pytariasis rosea rash’ noted. A routine sexual health screen was performed and serology for syphilis and HIV was also requested. STS were positive with a reactive EIA, reactive TPHA, and an RPR of 1:64. (Another example of how the rash of secondary syphilis may be easily misdiagnosed.) The lesion under his tongue could possibly have been a chancre. Syphilis may easily be transmitted by orogenital contact.
Syphilis was once a common disease both in developed and undeveloped countries. By the nineteenth century, syphilis was one of the most common diseases in the United States and Europe, especially in urban areas, where 8%–14% of the population had serological evidence of being infected.6 The advent of effective antibiotic therapy (in the form of penicillin) nearly came close to eradicating the disease in developed nations after the Second World War. As well as dramatically affecting the prevalence of syphilis, antibiotics have altered its clinical presentation and course. The causative organism Treponema pallidum pallidum, remains highly susceptible to many antibiotics, therefore late manifestations are seldom seen today.5
In New Zealand, the numbers of cases of syphilis have remained low for the last two and a half decades. A national rate was put at 3:100, 000 in 1977 and no change in incidence was reported from sexual health clinics between 1986 and 1993.7 However sentinel surveillance of STD clinic attendees between 1991–1992 found that a history of male-male sex was associated with higher rates of syphilis and gonorrhoea, and lower rates of chlamydia.8
Certainly the trend for low incidence rates of infectious syphilis appears to have reversed recently in other Western countries. For example, in the United States and Western Europe, there has been a resurgence in cases of infectious syphilis, particularly among MSM in the previous few years. After declining every year during 1990 to 2000, infectious syphilis rates increased in 2001 in the United States.9 There was a further 12.4% increase the following year and, as in 2001, the increase was primarily in men. In the United Kingdom, there have also been recent outbreaks of infectious syphilis. Between 1999 and 2000, the number of diagnoses of infectious syphilis in London rose by 41% from 154 cases to 217 cases.10 The largest rises were seen in MSM.
More locally, in the Pacific region, syphilis appears to be mainly a problem in heterosexuals. Fiji, in particular, is known to have high rates of syphilis infection and is also a common holiday destination for New Zealanders. A study looking at antenatal screening at a maternity unit in Suva in 1987, found that 14.2% of Fijian women and 1.1% of Indian women were seropositive for syphilis.11
What does this mean for New Zealand? Certainly there does appear to have been a recent increase in the numbers of people being diagnosed with infectious syphilis at ASHS, with a total of 40 cases between January 2002 and September 2004. These were twice as many cases as were diagnosed in the preceding 4 years (January 1998 to December 2001). (We have also had anecdotal reports from other hospital services that they appear to be seeing more cases of infectious syphilis than is usual. Unfortunately as other hospital services do not participate in STI surveillance this data will not be reported anywhere.)
The fact that MSM comprised 45% of the sample and that the majority acquired their infection in New Zealand suggests that we may be starting to experience a similar trend to Australia and other Western countries. But the disease still appears to be relatively rare in heterosexuals who have not had sex overseas.
What could be contributing to this apparent increase in infectious syphilis in Auckland? The increased rates in MSM could also possibly be related to a reduction in safer sex practices in recent years. Forty five percent of participants in the Gay Auckland Periodic Sex Survey12 reported never or infrequently using condoms for anal intercourse with regular partners.
Participants were much more likely to report using a condom for anal sex with casual partners than with regular partners, however 5% of men whom had a regular sexual partner also admitted to infrequent condom use with casual sexual partners. There is also some objective evidence of possible increases in unsafe sexual behaviour in MSM with the recent rise in HIV incidence in New Zealand. The number of new cases of HIV diagnosed in 2003 was higher than at any time since surveillance began13 with 71 new infections identified - a rise of 37% over 2002.
Men who have sex with men still make up the majority of cases (74%) where infection was acquired in New Zealand. This recent rise in HIV incidence is concerning AIDS epidemiologists. If we are also experiencing a rise in the incidence of infectious syphilis in New Zealand it could influence the HIV epidemic, as syphilis (to a greater degree than other bacterial STI) is known to markedly enhance HIV transmission.
The apparent increase in heterosexual cases may be a reflection of the fact that many New Zealanders now travel overseas to countries with high endemic rates of syphilis. Travellers often have casual sexual relationships when on holiday14 and may take risks under the influence of drugs and alcohol. Indeed, overseas travel seems to be responsible for a small but important proportion of acute STIs in other Western countries such as the United Kingdom. For example, in one genitourinary medicine clinic, 21% of infectious syphilis infections in heterosexual men were acquired from sexual contacts abroad.14
The increase in syphilis incidence is a potential serious public health issue and more information is required on its epidemiology in New Zealand. The most expedient manner to gather more information would be to make infectious syphilis a notifiable condition so that anonymous data can be collected in a similar manner to HIV infection.
In particular, medical practitioners need to be aware that syphilis infection is occurring in New Zealand. As well as pregnant women, those who should be screened for syphilis include New Zealanders who have had sex overseas, recent immigrants, and men who have sex with men. Asymptomatic people with these risk factors need to be screened serologically 2–3 months after suspected exposure. Any person suspected of having infectious syphilis should be urgently referred to a sexual health physician for evaluation, treatment, and contact tracing.
Author information: Sunita Azariah, Sexual Health Physician (and Fellow of the Australasian Chapter of Sexual Health Medicine, RACP), Auckland Sexual Health Service, Auckland City Hospital, Auckland
Correspondence: Dr Sunita Azariah, Auckland Sexual Health Service, Building 16, Auckland City Hospital, Private Bag 92024, Auckland. Fax: (09) 307 2884; email: SunitaA@adhb.govt.nz
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