Syphilis cases are on the rise. Among people 15 to 49 years old, there are 8 million cases, most in low- and middle-income countries. Syphilis can be transmitted to the foetus in pregnant women or at birth. It causes severe complications and death. Syphilis diagnosis is highly complex. Point-of-care diagnostics are urgently needed to identify infectious cases and distinguish them from previously treated cases.
We aim to:
2022–ongoing.
We’ve developed a rapid, simple-to-use point-of-care diagnostic test using finger prick blood. It provides a result within 15 minutes. The result indicates whether a person has active syphilis and should be prioritised for further testing and antibiotic treatment.
Our test is amenable to self-testing as well as use by health care professionals. It has been licensed to Atomo Diagnostics. The test is adaptable to ELISA and bead-based assays for use in laboratory settings and serosurveillance.
In 2022, the World Health Organization (WHO) reported that there were:
Reference: respective Global Health Sector Strategies on HIV, viral hepatitis and sexually transmitted infections for the period 2022-2030 (GHSS).
In Australia, syphilis case rates have doubled between 2015 and 2022. There were 6600 notifications in 2023, 82% in men who have sex with men in urban areas. In rural areas, Aboriginal and Torres Strait islander people represent 93% of cases. Globally, in 2022, 700,000 cases of congenital syphilis were reported. In some countries, congenital syphilis rates have double in the past 5 years.
Congenital syphilis can cause miscarriage, stillbirth, premature birth and lifelong health issues for the baby. While treatment of syphilis requires a single injection of long-acting penicillin, antibiotic-resistance has not yet been reported as a problem.
Most syphilis-infected individuals require two tests to distinguish current active infection from a previously treated infection. This includes an initial screen to report the presence of antibodies. It also includes a confirmatory test to determine if the syphilis infection is current and requires treatment.
Alternatively, if sores are present, a PCR test can be used to diagnose syphilis. The tests generally occur in a centralised laboratory. This can lead to delays in treatment and loss to follow up.
In resource-poor settings or clinics without follow-up capabilities, single tests are often used and there is a potential for over-treatment. An example is treating people with past-treated infections who are suspected to have active syphilis.
In some countries, antibodies to the closely related Treponemal species, which causes yaws, can cross-react with syphilis in point-of-care tests. This can lead to over-diagnosis of syphilis and over-use of antibiotics.
Our test aims to provide new pathways for the detection of cases of syphilis globally and prioritisation of people for antibiotic treatment. Improved detection will lead to a reduction of community transmission syphilis and contribute to the WHO goals of triple elimination.
Treponema pallidum pallidum (syphilis) and Treponema pallidum pertenue (yaws) are near identical bacterial species but cause different diseases. In populations with a high prevalence of yaws, current point of care diagnostic assays used for syphilis are likely to over-estimate the presence of syphilis due to cross reactive antibodies to yaws.
Student opportunities are available to develop ELISA and bead-based assays (Luminex, Bioplex) for the purpose of performing wide-spread screening of the prevalence of active syphilis and yaws in populations. In this project, students will express antigens from syphilis and yaws and use directly in ELISA or couple antigens to beads for bioplex assays. Serological samples will then be screened to examine the prevalence of antibodies and whether specific antigen combinations can distinguish to these two closely related Treponema species.
The outcome of this project are novel diagnostics assays to distinguish yaws and syphilis for use in population wide screening and diagnosis in low resource settings to accelerate people onto appropriate antibiotic therapy.
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