Diagnosis of hiv pdf
The use of DBS or dried plasma spot DPS specimens for quantification of viral load should take into consideration the specimen volume collected on the filter paper and used in the available assays. Retesting refers to repeating more than once a test using the same assay and where possible, the same specimen Every laboratory should have a quality assurance program in place to continuously assess and improve the processes integral to the production of laboratory results. Once breastfeeding is completely discontinued, it is considered that virological tests conducted at least six weeks after discontinuation of breastfeeding are indicative of true HIV infection status, i. The latter has superb specificity and is used for ruling in the diagnosis when a sample tests positive with ELISA. The most commonly used methodologies to detect nucleic acids are: Polymerase chain reaction PCR : it exponentially amplifies the DNA target by many orders of magnitude by cycling the temperature of the reaction several times. According to the objective of testing, the most appropriate test is chosen based on convenience, test characteristics, and the population to whom the testing subject belongs.
Laboratory diagnosis of human immunodeficiency virus (HIV) infection is antibody-based assays to the new tests for the detection of HIV nucleic acids.
3. DIAGNOSIS OF HIV INFECTION
Consolidated guidelines on the use of antiretroviral drugs for treating and preventing HIV infection. 2 CLINICAL GUIDELINES: HIV DIAGNOSIS. Introduction. DIAGNOSIS OF HIV INFECTION.
Kenny CW CHAN. Tests for HIV differ in methodology as well as testing purpose. Generally, tests are done for three reasons.
All aspects of handling of patient specimens from their arrival in the laboratory to the reporting of results must be monitored, documented and subject to quality control procedures. They are implemented as standard in many developed countries, including Hong Kong, to assure the safety of blood supply.
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The major performance and operational characteristics of commercially available serological assays are summarized in WHO reports available on the web site of the department of Essential Health Technologies As indeterminate results may also underlie an early evolving HIV infection, longitudinal follow-up with reassessment of risk of HIV infection and repeat testing is required.
Over the years, experience with the serologic tests and knowledge of viral subtypes helped refine testing algorithms that have high sensitivity and specificity for the purpose of clinical diagnosis.
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|J Clin Microbiol ; 40 POC testing is testing carried out wherever the patient is located - in a clinic, hospital or doctor's office.
The use of such testing varies across Canada, with some provinces not using it at all and others using it extensively in sexually transmitted infection clinics or hospitals and as a preliminary screen for needlestick exposures in a health care setting 8.
However, in those with low viral loads, false positives are possible. Dried specimens carry less biohazard risk than liquid specimens. In follow-up, patients will either show a definitive pattern indicating that they have seroconverted or will demonstrate the same banding pattern as previously observed.
Laboratory tests employed for the diagnosis of HIV infection may be classified into the following groups.
Antibody based. HIV infection is identified either by the detection of HIV-specific antibodies in serum or plasma or by demonstrating the presence of the virus by nucleic acid. The definitive diagnosis of HIV infection at any age requires diagnostic testing that confirms the presence of HIV. Serological testing identifies HIV antigen and/ or.
Recommended clinical guidelines on the prevention of perinatal HIV transmission, Participation in proficiency testing is a key component of any laboratory quality assurance program, whether available locally, nationally or internationally Positive results that are repeatable must be confirmed with a neutralization procedure.
This makes them particularly cost-effective for use in centralized surveillance and blood transfusion services and less suitable for lower-throughput facilities. MMWR ;54 Dispatch Specimens that are unlabelled, improperly labelled or do not match the accompanying requisition should not be tested by the laboratory in most circumstances.
It is also used to help determine the patient's response to therapy.
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|The promptness and reliability of the supply chain management and logistics system should be evaluated at each point in the chain to minimize total turnaround time.
The testing strategies described in this document do not refer to retesting, but rather to carrying out one, two or three tests using different HIV assays. Information on standardization of materials, specimen collection protocols, specimen handling and documentation supporting widespread implementation of programmes in clinical settings for HIV NAT testing using DBS can be found online 89 When the first and second test results are both reactive, a third different assay must be performed on the same specimen to confirm seropositivity.
Blood venous or capillary must be drawn from the infant or young child for all methods of virological testing and serological assays. Most assays currently in use are validated for use on serum, including serum collected in serum separator tubes and plasma collected in EDTA, sodium heparin, sodium citrate, acid-citrate-dextrose, cell preparation tube or potassium oxalate.
Video: Diagnosis of hiv pdf Diagnosis and Testing of HIV Infection
When external proficiency programs are not available, groups of laboratories may set up their own proficiency testing program by sharing samples among themselves.
The laboratory diagnosis of HIV infections
This topic will address screening and diagnostic testing for HIV infection in adults in clinical care settings. Detailed information about screening for HIV in the.
WHO Prequalification is a voluntary process, usually at the request of the manufacturer, and the results of these evaluations are made available online It is recommended that countries use serological assays rapid tests or EIAs within a testing algorithm that has been validated in-country by the National Reference Laboratory or another laboratory designated for this purpose.
Author information Copyright and License information Disclaimer. Infectivity is high in the seroconversion period and counselling on measures to reduce transmission should be given. The p24 protein is a product of the gag gene and resides in the viral core.
Diagnosis of hiv pdf
|Rapid test supports decision in the use of antiretroviral therapy to prevent mother-to-child transmission of HIV.
Additional information can be found in WHO publications Over the years, experience with the serologic tests and knowledge of viral subtypes helped refine testing algorithms that have high sensitivity and specificity for the purpose of clinical diagnosis.
WB requires sophisticated equipment, is technically demanding and needs expertise in interpretation.
In a small number of early seroconverters who are still in the 'window period', the p24 antigen may become positive before antibody is detectable.