Rapid tests for HIV infection have shown the potential for such tests to be rapidly and widely introduced in both developed and developing countries. Having been evaluated by WHO and shown to be both sensitive and specific, they became available at affordable prices through the WHO bulk procurement programme, and were approved for use in the USA by the Food and Drug Administration. The demand for an immediate result, and the advantages in terms of patient management, are so great that rapid tests are now routinely used in voluntary counselling and testing centres and antenatal clinics worldwide. This will hopefully be similar for rapid STI tests that fulfill the ASSURED criteria. However, there are 10 areas where more work is needed before STI tests can be widely used.
1. Continued search for ASSURED tests
The ASSURED score card based on select STI tests evaluated in this supplement is shown in table 5.21,22,23,24,31,32,33
Table 5Score card for current rapid STI tests
Mathematical models developed at the Tanzania site for prenatal syphilis screening showed that screening with rapid tests is cost‐effective if the price per test does not exceed US$0.63.25
Currently eight rapid syphilis tests evaluated by the SDI are included in the WHO Bulk Procurement Scheme at negotiated pricing ranging from US$0.19–1.00. Improved tests for syphilis that can distinguish between active and past treated infection are still needed. The US Centers for Disease Control and Prevention has been assisting test developers and manufacturers to develop rapid tests that will combine non‐treponemal and treponemal test on a solid phase, in either a flow‐through or immunochromatographic strip format. These prototypes will soon be ready for evaluation.
Clearly there is a need for more sensitive, simpler and cheaper rapid tests for C trachomatis
and N gonorrhoeae
Gift et al
have shown that a rapid test with a sensitivity of 65% can lead to a greater proportion of infected patients treated compared to a nucleic acid amplified test with a sensitivity of 90%, when the return rate for test results and treatment is low.38
Mathematical models developed using data from the SDI site in Benin showed that rapid tests with sensitivity of 70% and specificity of 98% have the potential to reduce the prevalence of these infections in sex workers and the potential to avert HIV infections in their clients.39
Encouraging data on an improved rapid test for ocular chlamydial infection have recently been published,40
and a number of tests for gonorrhoea await evaluation by SDI.
2. Piloting a road map for test introduction
Too often, research findings are not effectively translated into control strategies, policies and programmes.41
There is a gap between demonstrating the effectiveness of a novel intervention in a demonstration project and its adoption to scale in countries. In preparation for introduction of rapid tests into settings where no previous testing was possible, SDI conducted consultations in several regions of the world to define the key elements required for the successful and sustainable introduction of rapid syphilis tests (table 6). These activities form a basic road map for the introduction of new tools that can be used for diagnostics, vaccines and medicines.
Table 6Key elements of a road map for the introduction of rapid STI tests
As a result of the SDI regional consultations, 12 countries have initiated the development of a road map for the introduction of syphilis screening in their country. Such a road map can be broadly used for the introduction of other technologies for a variety of infectious diseases.
3. Developing sustainable diagnostic quality assurance programmes
Increasing access to testing in primary care settings means that tests will be stored at temperatures in excess of 30°C and no longer be performed by trained laboratory technicians. It is therefore critical that countries set up external quality assurance (EQA) schemes to ensure that the quality of the tests has not been compromised during storage and that health workers are proficient at performing the tests. These national schemes can be developed in conjunction with quality assurance schemes for other diagnostic testing and should be supported technically by a network of expert laboratories, inside and outside of the country. This requires the development of a business plan for obtaining sufficient funds to cover set up costs and identify means of sustaining the programme.
4. Taking advantage of available programme infrastructure and resources
Capacity for introduction of new tools varies significantly between countries, and between rural and urban areas within countries. The success of increasing access to syphilis screening depends on the level of political commitment, the existence of a robust health infrastructure to facilitate the implementation, and the availability of screening tools. In resource limited settings, health service providers have to prioritise their scarce monetary and human resources to accommodate many competing demands. There are also operational and administrative difficulties such as frequent stock‐outs of tests or drugs for treatment, leading to poor motivation in implementing and scaling‐up screening services. Instead of setting up a new infrastructure for decentralised STI diagnostic services, every effort should be made to take advantage of new or existing initiatives, such as antenatal care programmes, Prevention of Mother to Child Transmission programmes for HIV, and HIV Voluntary Counselling and Testing programmes.
5. Using the internet more creatively
In recent years, the internet has emerged as a risk environment for STIs and many STI testing services are available from the internet.42,43,44,45
The sensitivity of nucleic acid amplification tests has made it possible to use non‐invasive specimens, such as urine or vaginal swabs, for the diagnosis of bacterial STIs. As these specimens can be stored and transported at ambient temperatures, there has been a proliferation of internet‐based STI testing services. The type of tests and the quality of testing used on these internet services are unknown. Simple rapid STI tests are sold on the internet or “over the counter”. Few countries regulate STI tests sold through these venues. STI control programmes need to exploit the popularity of the internet to provide scientific information to health care professionals and the lay public on how STIs should be diagnosed and treated, and make the public aware of the consequences of misdiagnosis.
6. Ensuring a sustained effort at disease control programmes
The availability of new tools that can be used to increase coverage for prenatal screening has sparked interest in planning for the global elimination of congenital syphilis. While “eradication” or “elimination” are laudable goals, eradication has been achieved for smallpox, and is being pursued for river blindness and polio, with local success in some regions. Another treponematosis, yaws, has been eliminated from some regions, but not globally. Elimination of syphilis is being pursued in the USA, and has been achieved transiently in some areas of the world, such as China and King County, Washington, USA. However, it returned with a vengeance as sexual behaviours and patterns of sexual mixing changed.46,47
Syphilis outbreaks elsewhere in the USA, eastern Europe and the Russian Federation are also testament to the resilience of the pathogen.48,49
In general, the concept of elimination of syphilis, given available tools, is unrealistic and diverts attention for the need for continuous and sustained control programmes. The addition of ASSURED rapid diagnostics for syphilis, as one component of a sustained effort, can improve the potential for better control of adverse consequences of syphilis globally regardless of ongoing endemic disease.
7. Defining the role of rapid diagnostics for viral STIs
Recent studies have identified herpes simplex virus 2 (HSV‐2) as a major risk factor for the acquisition and transmission of HIV.50
A vaccine for human papilloma virus (HPV) has been shown to be effective in preventing the infection by the major oncogenic types.51
Although the role of diagnostics in the control of many viral STIs remains unclear, more strategic planning needs to be given to the role of diagnostics in the control and prevention of HSV.
8. Assessing the need for rapid tests for vaginal discharge
The syndromic management of vaginal discharge remains problematic. Rapid tests could improve the specificity of syndromic management. The performance, operational characteristics and costs of rapid tests for C trachomatis, N gonorrhoeae, Trichomonas vaginalis and bacterial vaginosis are now available. In the absence of a multiplex test, the cost of using multiple rapid tests to detect all the major causes of this syndrome may be prohibitive, and certainly not cost‐effective compared to presumptive treatment. A consensus meeting to review and recommend how these tests should be used in the management of vaginal discharge is warranted.
9. Developing a consensus on how rapid tests for C trachomatis and N gonorrhoeae should be used
The performance and operational characteristics of rapid tests for the screening and case management of individuals with genital chlamydial and gonococcal infections need to be better defined. Given the psychosocial consequences of a misdiagnosis for STIs, tests should be highly specific. From the perspective of STI control programmes, rapid tests can improve control of STIs in high risk populations. In the general population, where the prevalence may be low, even a test with a specificity of 98% may yield more false than true positives. Once rapid tests become commercially available, it would be difficult to prevent their widespread use. Guidelines are needed on how rapid tests should be used and updated as test performance improves.
10. Inclusion of STI diagnostics as part of an essential diagnostics package for improving health in developing countries
The control of infectious diseases of public health importance in the developing world is often hampered by lack of resources. WHO has developed an Essential Medicines package with the aims of ensuring that public health programmes in developing countries have access to medicines that are deemed essential for a sound public health programme. As it is increasingly clear that the lack of affordable appropriate diagnostics is a major barrier to health in the developing world, an essential diagnostics package that includes rapid tests for HIV, tuberculosis, malaria and STIs should be developed.