The real Medical Lab Scientist Explanation of:
Which is the most accurate test for HIV?
Best time to take HIV tests
When to get tested for HIV AIDS virus?
False positive/negative HIV test results
HIV is the human immunodeficiency virus, virus causing AIDS disease.
The median time from infection to the development of AIDS is about 10 years.
More Information about the HIV virus results here.
Types of HIV testing Kits:
The specific the HIV test the earlier and effective the treatment.
Antibody HIV tests:
HIV Virus Antibodies can take up to 6 – 8 months to show up in the Blood.
they detect HIV antibodies, hence it may not valid for early detection of HIV, because body takes up to 4 weeks to produce enough antibodies against virus’s antigens.
Antigens HIV tests:
HIV aids Antigens shows up in the blood tests in 2-4 weeks after infection.
It is the tests of choice to early detecting Virus more than 2 weeks earlier than HIV Ab tests, because HIV Ag tests detect the core body of the virus (Antigen), thus HIV virus can be detected earlier and treatment starts earlier and effectively taken.
Quantitative Ag/Ab HIV tests
Time to get results: 1 – 3 business days.
Test Accuracy: Most accurate HIV tests, also depends on lab, device, and Kit.
How to take swab sample for HIV test?
Swabs the upper and lower gums of your mouth, places the sample in a Sterile vial or cup.
Modern Point of Care Tests to diagnose HIV virus
POC HIV test for aids virus, which test a sample of saliva taken from the mouth or a spot of blood taken from pricking a finger with a needle. The result is available within a few minutes, in the clinic.
Rapid HIV antibody tests:
Specimen: Blood drops, Saliva
Test time: Results are available within 30 minutes.
Rapid antibody/antigen test.
One antibody/antigen test kits
Specimen: Blood, Saliva
Test Results time: 20 minutes.
HIV Aids Home test kits:
Available Packs to test yourself securely at home or send to lab anonymously.
Positive Results must be confirmed by a Laboratory test.
Test Results time: 20-40 minutes.
Read about reasons of False test results. here
First blood test run by smartphone
It gives HIV, syphilis results in 15 minutes
The results of the study, which was published Wednesday in the journal Science Translational Medicine, were just as reliable as those you’d get in a professional lab, Sia said.
Researchers have invented a smartphone device that performs a quick — and reliable — blood test in the field to check for infections.
The device — known as a dongle — only requires a pinprick of blood, with results available in 15 minutes. The accessory, which plugs into a smartphone or computer and runs off an app, is lightweight and inexpensive. Though not commercially available yet, its developer, Samuel Sia, estimated it would retail for about $45.
He said it is the first blood test for a smartphone.
Screening HIV AIDS for the first time:
Qualitative Serum HIV-1,2 test
An initial screen test used to diagnose HIV infection with >99% sensitivity.
There are two types of HIV, 1 and 2. HIV-1 is the most common type found in the United States, while HIV-2 has a higher prevalence in parts of Africa.
HIV-1 (the commonest) and HIV-2. A DNA-based test is available for babies born to seropositive mothers.
Testing Methods and Normal Values:
HIV Antibody, ELISA: negative
HIV Western Blot: negative, more accurate, confirm Positive routine test results.
HIV Antigen (P-24 Antigen): negative
HIV Viral load: 50 copies/mL
■ Positive Results must be confirmed with Quantitative HIV test.
HIV AIDS confirmation Tests
Usually PCR is used to confirm Positive HIV results.
Viral Load (Plasma Viral Load, PVL, PCR)
Tests are performed serially with treatment changes to monitor treatment response. Best time to get HIV-RNA PCR test is 2- 4 weeks after starting treatment
Specimen: Blood only
Normal Range: Negative or Undetectable Virus.
The lowest level of detection: at present is 200–500 copies/ml).
High Levels: 10,000 copies/mL or more is considered high.
■ High PCR means rapid HIV virus Progression, Low HIV PCR count means slower disease progression or the treatment is effective to lower the virus concentration in the plasma.
Follow up and After Diagnosis HIV tests
Used After Diagnosis and confirmation that HIV virus is exist.
Effectiveness of the treatment course or there is Drug resistance and virus mutation.
How complicated the virus symptoms is going to be.
HIV AIDS Monitoring tests
Tests to follow up AIDS symptoms for treatment purposes.
1- WBC differential Count:
Decreased white blood cell count is called leukopenia.
◆ Decreased lymphocytes is the hallmark of AIDS. It also occurs in acute infections, Hodgkin’s disease, leukemia, sepsis, systemic lupus, renal failure, and radiation sickness.
2- Lymphocyte Assay (CD4 marker, CD4/CD8 Ratio)
T cells: 60–80% or 600–2400 cells/ L
B cells: 4–16% or 50–250 cells/ L
CD4: 493–1191 L
CD8: 182–785 L; CD4/CD8 Ratio: 1
CD4 count. CD4 is a protein found on the surface of T-helper cells (Specific WBC invading Pathogens). HIV targets these immune cells.
Low CD4 count means Low immunity .
Critical Limit which is require urgent medical decision is CD4 equal to 500 cells/mm3.
CD4 count Lower than 200/mm3, called full-blown AIDS.
■ Assessed in the diagnosis of AIDS, leukemias, lymphomas.
■ Used to guide drug therapy decisions in HIV infection and AIDS.
3- Platelet Antibodies (Antiplatelet Antibodies)
Normal Value: Negative
■ Antibodies to platelets can result from an autoimmune response or a reaction to transfused blood products.
■ The antibodies cause destruction of donor and native platelets.
■ Positive platelet antibodies are found in AIDS, acute myeloid leukemia, immune complex diseases, drug-induced thrombocytopenia, posttransfusion purpura, and idiopathic thrombocytopenia purpura.
4- Platelets count:
Normal Levels: 150 – 400 cells/mm3
Low Platelet count is seen in HIV Patients, called immune thrombocytopenia.
5- Beta 2 microglobulin
ref. range: ß2 microglobulin is elevated in autoimmune conditions where there is lymphocyte
activation or destruction.
IV . levels above 4.0 g/L are more likely to progress to AIDS
multiple myeloma . used for monitoring and prognosis
6- Cryptosporidium faecal Test
In immunocompromised patients (especially those with HIV), Cryptosporidium may cause
a severe prolonged watery diarrhoeal illness. Stool sample tested on request and fast treatment is required.
7- Common Body Checkup
Routine tests may be taken too to measure the levels of sodium, potassium, creatinine, blood urea nitrogen, and albumin, urinalysis, Cholesterol and triglyceride tests (high in AIDS PT.s).
8- Tests for Possible second infection
HIV Patients have a great risk for other sexually transmitted diseases (STDs), such as gonorrhea, syphilis, herpes, and Chlamydia, or other infection as hepatitis, tuberculosis, and toxoplasmosis.
Symptoms and Lab tests Relationships:
Some people living with HIV have no signs and symptoms for many years.
People who have recently been infected with HIV often experience a short, flu-like illness two to six weeks after infection. Symptoms include fever, sore throat, and body rash.
Early symptoms of HIV include exacerbation of previous skin disease, e.g. eczema, somewhat recalcitrant tinea, surprising shingles, oral candidiasis, recalcitrant vaginal candidiasis : in other words, common or ordinary events occurring oddly or excessively.
Lymphoma predisposes to HIV infection and HIV is an uncommon cause of acute
Pneumocystis carinii pneumonia (found only when patients have CD4 counts
How to read test results?
Are you know when to take HIV test?
please read my previous topic.
Where HIV testing is available in your area?
Call: 800-CDC-INFO (232-4636).
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