Dual Point-of-care Test for the Diagnosis of Yaws
Condition: Yaws
MeSH terms: Yaws
Study type: Observational

Summary: 
      A dual POC immunoassay simultaneously detecting non-treponemal and treponemal antibodies was
      developed for the diagnosis of infections with T. pallidum. The assay is designed for use in
      resource-limited settings where challenging conditions (such as lack of electricity, running
      water, or laboratory equipment) commonly exist. We sought to compare performance of the
      dual-POC assay for diagnosis of yaws infection with that of the RPR and TPHA as reference
      standards.
    

Detailed description: 
      Yaws is an infectious disease caused by Treponema pallidum subspecies pertenue, a bacterium
      which closely resembles the causative agent of syphilis, and is spread by skin to skin
      contact. In the field, yaws is diagnosed on the basis of epidemiological context, evocative
      symptoms and signs and positive serological tests or dark field microscopy. The darkfield
      microscopy is not easy to perform , hence the interest in serological tests. The serological
      tests used to confirm yaws are the same as those used to diagnose syphilis. Yaws serologic
      diagnosis relies on testing for non-treponemal and treponemal antibodies. These antibodies
      differ markedly with respect to antigenic reactivities and kinetics during the disease
      process.

      Historically screening for yaws has involved the use of nontreponemal tests, such as rapid
      plasma reagin or venereal disease research laboratory. Positive results of nontreponemal
      tests of specimens are then confirmed using a more specific treponemal test, such as
      Treponema pallidum haemagglutination. However, the equipment and personnel requirements for
      conducting and interpreting these laboratory-tests are rarely available in low-resource
      settings in developing countries where yaws occurs.

      Rapid treponemal tests which detect antibodies to T. pallidum antigen have become popular for
      the diagnosis of venereal syphilis due to their many advantages. These tests that can be
      performed outside a laboratory setting with minimal training and using blood collected by a
      finger prick, which makes them extremely useful in remote areas where laboratories are not
      available. However, the rapid treponemal tests for syphilis detect treponemal antibodies,
      which limits their use for interpretation of the disease status since they cannot distinguish
      between active and past or treated infection.

      A combined point-of-care (POC) test which detects both treponemal and non-treponemal
      antibodies has recently been evaluated for the diagnosis of syphilis, and appears promising
      for yaws diagnosis. The use of the dual POC test would result in the ability to both screen
      and confirm the serological status of patients with suspected yaws within 15 minutes and give
      a better indication of active disease.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Patients will be recruited from Lihir Island villages in April 2013. This community has
        been described previously. We will conduct community-based surveys and we invited children
        aged 1 - 15 years suspected to have yaws by clinical examination to participate in the
        study. All children for whom a parent or guardian gives written informed consent will be
        included consecutively
      
Keywords: Diagnosis; Rapid tests; non-treponemal serology; eradication