Clinical Focus
14 JULY 2023 ausdoc . com . au
Therapy Update
Managing the
great mimic
GPs have a vital role to play in addressing rising syphilis rates and combating congenital cases .
First published online on 20 May 2023
The STI Atlas 21
INFECTIOUS syphilis notification rates in Australia have been steadily increasing since 2011 , with the majority of cases affecting gay , bisexual and other men who have sex with men . 1-4 That said , there has been a recent re-emergence of infections among heterosexual populations . 5
Rates of infectious syphilis in women of reproductive age increased by 233 % between 2015 and 2020 . 6 Consequently , rates of congenital syphilis cases in Australia are increasing . 6-8 For the first time in decades , congenital syphilis cases have been seen in urban centres around Australia . 9
Another consequence of rising syphilis
Figure 1 . Primary syphilis . Very early penile chancre — papule of early syphilis prior to ulceration .
Figure 2 . Secondary syphilis . Rash on back . 21
Sexual health
Dr Sarah Borg ( left ) is a sexual health registrar at Melbourne Sexual Health Centre , Alfred Health ; and a public health registrar at the Burnet Institute , Melbourne , Victoria .
Dr Ranjit Samra ( centre ) is a dual-training infectious diseases registrar and sexual health registrar at Melbourne Sexual Health Centre , Alfred Health , Melbourne , Victoria .
Adjunct Professor Marcus Chen ( right ) is a sexual health physician at Melbourne Sexual Health Centre , Alfred Health ; and adjunct professor at the central clinical school , faculty of medicine , nursing and health sciences , Monash University , Melbourne , Victoria .
rates is an increase in the number of neurosyphilis-related hospital admissions in Australia . 10
Infection rates among Aboriginal and Torres Strait Islander peoples are much higher than among the non-Indigenous Australian population . 4 Since 2011 , there has been a multi-jurisdictional infectious syphilis outbreak affecting young Aboriginal and Torres Strait Islander peoples living in Queensland , the NT , WA and SA . 11
These factors highlight the importance of primary care and sexual health services being alert to potential symptoms of this great mimic and opportunistically screening groups at risk .
Transmission
Syphilis is caused by the bacterium Treponema pallidum . 12 It is transmitted through sexual contact , blood transfusion or transplacentally . 13
Syphilis infection is usually spread by oral , vaginal or anal sexual intercourse with an individual with infectious syphilis . 13 Asymptomatic shedding of T . pallidum may occur from the mouth and anus in the absence of obvious lesions . 14-16
Early syphilis is defined as syphilis of less than two years ’ duration and includes primary , secondary and early latent syphilis . Syphilis of more than two years ’ duration is regarded as late syphilis . Early syphilis is infectious . The distinction between early and late infection dictates the treatment required . 13
Clinical features
The presentation of this condition is highly variable — often involving clinically mild or atypical symptoms and signs . 13 , 17 , 18 Symptoms are often unrecognised by patients and misdiagnosed by healthcare providers . 17 , 18 Thus , a high index of suspicion and asymptomatic screening are required . 19
Primary syphilis is characterised by the presence of the primary lesion at the site of inoculation — for example , mouth , vulva , penis ( see figure 1 ) or anus . 13 The classically described primary chancre is a single painless ulcer with indurated margins . 20 However , a painful and / or multiple primary ulcers also commonly occur , mimicking HSV infection . 17 The primary lesion ( s ) will resolve spontaneously over a number of weeks . 13
Secondary syphilis usually occurs weeks to months later and is characterised by a generalised rash . 20 This can affect the torso and limbs and sometimes the palms of the hand and soles of the feet . The appearance of the rash is highly variable and can be macular or papular — often mimicking other skin conditions , such as viral infections or psoriasis . Some individuals with secondary syphilis report systemic symptoms , including sore throat , lymphadenopathy and fatigue ; rarely , acute hepatitis is seen . 13
Latent syphilis refers to infection detected by syphilis serology without symptoms or signs . It is classified as early latent if the infection is of less than two years ’ duration or late latent if the infection is of more than two years ’ duration . 13
If left untreated , a proportion of patients with late latent syphilis will eventually develop tertiary syphilis . This can present with cardiovascular and neurological disease . 13
Neurosyphilis can occur at any stage
NEED TO KNOW
Infectious syphilis cases are increasing in Australia , especially in women of reproductive age , resulting in an associated rise in congenital syphilis .
Clinical presentations of infectious syphilis are highly variable and often misdiagnosed , highlighting the importance of testing and asymptomatic screening .
All pregnant individuals should have a syphilis test at their first antenatal visit , with repeat testing later in pregnancy for those at higher risk .
Contact tracing and treating sexual contacts help to reduce syphilis reinfection rates and improve control .
Individuals diagnosed with syphilis should have a test for other STIs , including HIV .
and must be considered where abnormal ophthalmological — for example , visual changes — or neurological — for example , tinnitus , deafness , headache , cranial nerve palsies , meningitis — symptoms or signs are present . 13 This should trigger discussion with an experienced clinician to determine further investigation and
20 , 22 management .
Congenital syphilis may occur at any time during pregnancy . 13 Prematurity , stillbirth or severe multi-organ disease may result if syphilis in pregnancy is
13 , 22 , -24 untreated .
Testing indications
Indications for serological syphilis testing are outlined in box 1 . Regular screening is recommended for higher-risk groups , including young Aboriginal and Torres Strait Islander populations ; gay , bisexual and other men who have sex with men
Box 1 . When to test for syphilis 22
• As part of an asymptomatic STI screen
• Screening for higher-risk groups ( including young Indigenous populations , GBMSM , female partners of GBMSM and sex workers )
• STI symptoms
• Another STI diagnosis
• Sexual contact of any STI
• Pregnancy
• Clinical signs or symptoms , including genital , anal or oral lumps or ulcers without another known cause ; or an unexplained rash , alopecia , fever , persistent lymphadenopathy or deranged liver function