Dual Diagnostic Technologies

UZ-UCSF COLLABORATIVE RESEARCH PROGRAMME ANNUAL RESEARCH DAY 17 APRIL 2015

Dr Evaristo MarowaDermato-Venereologist

Approach to STI Case Management

• STIs are common and serious especially to women and neonates

• Effective case management is a cornerstone of control

• Given at “point of first contact” it:– Decreases spread and prevents

complications– Targets STI/HIV counselling and education

to a receptive audience

STI – Syndromic Case ManagementSTI – Syndromic Case Management

REQUIREMENTS

• Adequate medical history

• Good sexual history

• Complete STI clinical examination

• Management guidelines

• Good supply of effective medicines

2nd Generation Syndromic Diagnosis Approach

Action

Condom use

Other action

Partner notification

Symptom + signParticularly vaginal dischargeor GUD

Decision

Incorporate rapid diagnostic testRisk assessment

Decision flowchart for introducing a new diagnostic test

Yes No

Good

Is testing currently available or possible at the facility?

Access, coverage and quality?

• Maintain current system• Ensure

continued/improved quality control programme

Poor

Can current system be fixed?

Yes No

• Introduce new diagnostic test(s)

Current Rapid Tests for Syphilis(Equivalent to TPHA)

C TS

C TS

C TS

Negative Negative

Positive

Invalid

Procedure:1. Use dropper provided, dispense 1 drop of serum/whole blood to sample

well S 2. Add 2 drops of diluent buffer to sample well S3. Read results at 15 minutes

Bioline Treponemal Point-of-care (POC) Test

1. Add 5 l of serum/blood to the sample+buffer well.

2. Add 2 drops of buffer to the sample+buffer well.

3. Add five drops of buffer to the buffer well when the colored lines

disappear.

4. Read the results at 15 minutes

Negative result: one line Positive result: two linesor

12345678 12345678 12345678

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Chembio Syphilis POC Test ProcedureChembio Syphilis POC Test Procedure

Ideal, conventional diagnostic algorithm for the diagnosis of active syphilis – RPR+TPHA

Confirmed syphilisTREAT

No treatment necessary

Serum

RPR

+ve -ve

Treponemal test

+ve -ve

Figure 12

Patient Name or Number

CardiolipinAntigen Spot(RPR equivalent)

TreponemalAntigen Spot(TPHA equivalent)

ControlSpot

Span ‘Signal Spirolipin’ Flow-through Syphilis Dual Test

Platform

Addition of wash buffer

Addition of serum Addition of wash

buffer

Additionof conjugate

Addition of wash buffer

Step 1 Step 2 Step 3

Step 4 Step 5

Rapid Simultaneous Detection of Rapid Simultaneous Detection of Reagin and Treponemal AntibodiesReagin and Treponemal Antibodies

Using the ‘Signal Spirolipin’ Flow-through Test Using the ‘Signal Spirolipin’ Flow-through Test

NON –REACTIVE TESTS ONLY THE NON-SPECIFIC CARDIOLIPIN TEST REACTIVE

ONLY THE TREPONEMAL TEST REACTIVECONFIRMED REACTIVE TEST

Field testing by CDC-USA in Madagascar(Courtesy Prof Ron Ballard)

Chembio Dual Cardiolipin / Treponemal TestChembio Dual Cardiolipin / Treponemal Test

Whole Blood sample

Dual (combined) rapid syphilis diagnostic test

Tp –ve, NTp -veTp –ve, NTp +veTp +ve, NTp -veTp +ve, NTp +ve

Active infection.Initiate treatment

Past/early syphilisRetest in 4-6

weeks to confirm

Biological false +ve, no treatment

Uninfected, no treatment

Tp = Treponemal result Ntp = Non=treponemal result

Syphilis testing and treatment algorithm with dual diagnostic test

The Future: Dual testing for HIV and syphilis

Sexually Transmitted Infections

The future multiplex technology for diagnosis of urethral discharge

• Amplified nucleic acid based testing - for N. gonorrhoeae - for C. trachomatis - for M. genitalium - ? for U. urealyticum - for T. vaginalis

The future multiplex technology for diagnosis of vaginal discharge syndrome

• Amplified nucleic acid based testing - for T. vaginalis - for N. gonorrhoeae - for C. trachomatis - for M. genitalium

Criteria for choice of tests for purposes of procuremet

• Cost

• Test Performance

• Stability

• Need for additional supplies, e.g. micropipette

• Format: dipstick vs cassette

• Training required

• Ease of interpretation of results

• Regulatory approval in country

accuracyreproducibility

Quality Assurance

• Quality control of tests (QC)– Rapid tests have no internal QC– Need to monitor transport and storage conditions

(temperature and humidity)- Temperature spiking in transit- Storage at central stores- Storage at health-care facilities at all levels

• Quality of testing – EQA (proficiency)– Quality system throughout health-care infrastructure– National reference labs, regional, district, health

centre

The Future GoalThe Future Goal

• The development of integrated diagnostic platforms that are rapid, easy to use, sensitive and specific to detect multiple targets for diagnosis of infectious diseases

• oral rapid tests to screen for HIV/syphilis, other viral STIs

• Determination of antimicrobial resistance

• For monitoring treatment and prevention

• For use in peripheral point-of-care settings

• Access ensured in low resource settings

TatendaThank youMerci