Dual Point-of-care Test for the Diagnosis of Yaws (YARADI)

Oriol Mitja

Status: Completed

Conditions: Yaws

Study type: Observational

Funder types: Other

Identifiers

NCT01841203

YARADI

Details and patient eligibility

About

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.

Full 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.

Enrollment: 703 patients

Sex: All

Ages: 2 to 15 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• Children from 2 to 15 years with clinical suspicion of active yaws

Exclusion criteria

• Persons who are unable to sustain venipuncture; persons who do not provide an informed consent, or withdraw consent

Trial design

703 participants in 1 patient group

DPP/RPR-TPHA comparison

Description:

The evaluation of T1 (treponemal line) will be conducted by using the T1 positivity identified by naked eye or automated reader to compare with that of TPHA; while the evaluation of T2 (non-treponemal line) will be conducted by using the T2 positivity identified by naked eye, or automatic reader at cut-off value of 20, to compare with the result of RPR.