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Flashcards in HIV - POCT testing Deck (26)
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1
Q

How many types of HIV tests exist?

A

Two forms

2
Q

What are both HIV tests based on?

A

Immunoassay

3
Q

What are the two HIV tests that can be done?

A

A rapid finger-prick or mouth-swab POCT

A blood test requiring laboratory analysis

4
Q

Where are HIV tests done?

A

Sexual health clinics

Genitourinary medicine clinics

Some GP surgeries

Clinics run by charities

Antenatal clinics

Private clinics

5
Q

What are the two types of POCT tests?

A

3rd generation

4th generation

6
Q

What does the 3rd generation test for?

A

Only HIV antibodies

7
Q

What does the 4th generation test for?

A

HIV Ab and p24 antigen

Proteins on the envelope

Look for antigens before antibodies appear in the blood

8
Q

What is the window period?

A

Gap in antibody testing

Time between a persion is infected with HIV until the point when a test can detect HIV

9
Q

Why is the 4th generation test beneficial?

A

Reduces the window period of detecting HIV infection

10
Q

What is the window period for detecting antibodies (3rd generation)?

A

Usually after 6 months but almost certainly by 3 months after exposure

11
Q

What is the window period for detecting antigens (4th generation)?

A

14 - 21 days after exposure

12
Q

What is done before testing for HIV?

A

Must be a pre-test discussion

Needs to establish consent for the HIV test

Explain

  • what test will be given
  • how long the result will take to come back
  • how the result will be given to the patient

Confidential

Explain the benefits of knowing one’s HIV status and treatment possibilities

13
Q

What are the benefits of knowing the HIV status of a person?

A

Won’t spread to partner

The sooner diagnosed, the sooner can start getting treated

Implement a more healthy lifestyle

14
Q

What type of test is a POCT test?

A

Immunochromatographic lateral-flow assay

15
Q

What type of sample is needed for a POCT?

A

Finger prick

Mouth swab

16
Q

When do results of POCT come back?

A

POCT can produce results in minutes

20-30 minutes for a finger prick test

17
Q

What are the disadvantages of HIV POCT tests?

A

Reduced specificity and sensitivity

18
Q

What is the next steps when POCT tests come back positive?

A

Confirmed by a blood test

19
Q

What needs to be done if someone has been exposed to HIV in the last 3 months?

A

Needs to come to lab at 3 month period after exposure to take test again

Do laboratory test to investigate using 4th generation testing

20
Q

How is a HIV POCT Immunochromatographic lateral flow assay carried out?

A

Place blood from finger prick on the sample pad

Gold microparticle coated in HIV antigen placed on the sample pad

Nitrocellulose membrane contains HIV antigens which capture the gold microparticle immune complexes

Captured gold microparticles forms a red line when HIV atinbodies are present in the patient’s sample

Absorbant pad draws the sample across the reaction membrane

21
Q

What ensures that the POCT test was carried out correctly?

A

Control line

Shows assay worked properly

22
Q

How is the POCT 3rd and 4th generation tests confirmed?

A

Blood sample taken by venepuncture in the Virology department laboratory

23
Q

What is the average time for blood results to come back?

A

2-3 days

Can be fast-tracked to a matter of hours

24
Q

Which schemes have made it easier to test for HIV?

A

Increase the turn around for POCT tests

Outreach programmes

Walk in centers

Drop-in clinics

25
Q

How do drop-in clinics increase HIV testing?

A

No appointment needed

Convenient

Anonymous

Perceived as being friendly and non-judgemental

Non-invasive test

Fast results

Clinics sited in and targeted at high-risk communities

26
Q

What are the next steps one a POCT comes back positive or HIV?

A

HIV to be staged

Antiviral therapy commences

Prophylaxis against possible opportunistic infections if appropriate