Early Infant Diagnosis of HIV Dr Jayanthi . P.Elwitigala Consultant Microbiologist NSACP
• Worldwide, in 2008, an estimated 430 000 new infections due to HIV occurred in children • 90% were acquired through mother to- child transmission of HIV. • Of the 430 000 new infections, between 280 000 and 360 000 were acquired during labour and in the pre-partum period. • Of the remaining new infections, the majority were acquired during breastfeeding.
HIV transmission from mother to child • During pregnancy, labor and delivery, or breast feeding is known as perinatal transmission and is the most common route of HIV infection in children. • The risk of transmission is 25-30%
• Studies suggest that 35% of the infected child die in their 1st year, 50% die by 2nd year and 60% die by 3rd year, in resource limited settings. • However, women with HIV who take antiretroviral medication during pregnancy as recommended can reduce the risk of transmitting HIV to their babies to less than 1% (PMTCT programmes)
• Early Infant Diagnosis (EID) is crucial to reduce morbidity and mortality in HIV-infected children • The Children with HIV Early Antiretroviral Therapy (CHER) study showed that mortality among HIVinfected infants randomized to ART within the first 12 weeks of life was significantly reduced compared to those receiving later ART based on clinical criteria as per prior WHO guidelines. Violari A, Cotton MF, Gibb DM, et al. Early antiretroviral therapy and mortality among HIV-infected infants. N Engl J Med. 2008;359:2233–44.
Recently published data has confirmed dramatic survival benefits for infants started with ART. • Hence, it is strongly recommended that laboratory testing has to be carried out to diagnose HIV-1 infection in infants below 18 months. • However, very few infants are gaining access to early diagnosis and for the timely ART . • Addressing HIV/AIDS in Infants & Children below 18 months is significant global challenge
Who needs testing? • Two types of infants will need HIV diagnostic testing - Infants - HIV-exposed (mother known HIV positive) - Infants - sick with signs and symptoms of HIV, even if unknown HIV exposure status (referred by MO/Pediatrician) • Identification of infected infants can take place through one of the following: (If available ) – infant diagnosis algorithm used in the country – National pediatric guidelines
Diagnostic tests • HIV antibody detection assays, used to diagnose HIV infection in adults cannot be used early in life because of the persistence of maternal HIV antibodies acquired by passive transfer.
Clinical Guidelines Portal http://aidsinfo.nih.gov/ Diagnosis of HIV Infection in Infants and Children (Last updated: February 12, 2014; last reviewed: February 12, 2014)
Recommendations
• Virologic assays that directly detect HIV must be used to diagnose HIV infection in infants younger than 18 months (AII). • HIV DNA polymerase chain reaction and HIV RNA assays are recommended as preferred virologic assays (AII). • Virologic diagnostic testing in infants with known perinatal HIV exposure is recommended at ages 14 to 21 days, 1 to 2 months, and 4 to 6 months (AII).
• Virologic diagnostic testing at birth should be considered for infants at high risk of HIV infection • Virologic diagnostic testing should be considered 2 to 4 weeks after cessation of antiretroviral (ARV) prophylaxis for infants receiving combination ARV infant prophylaxis, if the results of prior virologic testing were negative while the infant was receiving prophylaxis • A positive virologic test should be confirmed as soon as possible by a repeat virologic test on a second specimen
WHO Recommendation 3: • It is strongly recommended that HIV virological testing be used to diagnose HIV infection in infants and children below 18 months of age. (Strong recommendation – High quality of evidence)
Recommendation 4: In infants and children undergoing virological testing, the following assays (and respective specimen types) are strongly recommended for use: • HIV DNA on whole blood specimen or DBS; • HIV RNA on plasma or DBS; • Us p24 Ag on plasma or DBS. (Strong recommendation – High quality of evidence)
Recommendation 5: It is strongly recommended that all HIV-exposed infants have HIV virological testing at 4–6 weeks of age or at the earliest opportunity thereafter.
• The current test of choice in HIV care and treatment program is the HIV-1 DNA PCR test which detects HIV-1 Proviral DNA integrated in Human Genome. Sensitivity (99.3%) and Specificity (99.6%)(Shermann et al., 2005 ) • HIV RNA PCR and other nucleic acid detection techniques have also proved accurate and reliable & they provide additional information about virological status that can assist in clinical management (However, false positive results can occur although rarely as a result of laboratory and operator error.)
HIV Life Cycle : Pre-integration
Reverse Transcription
dsDNA
cDNA
ssRNA
Fusion
Penetration and Uncoating
Nuclear Transport
Integration
Host chromosome
Host Cell
HIV Life Cycle: Post-integration Budding
Proteins
Assembly Translation Maturation mRNA ssRNA
Transcription
Host Cell
DBS • With the development of dried blood spot (DBS) method to simplify sample management and transport, polymerase chain reaction (PCR) testing of infants has become feasible in rural settings using centralized laboratories. The use of DBS-PCR methods in infants has been demonstrated to be both highly sensitive and specific, enabling EID in even resource-limited settings
DBS • The child is pricked and blood is collected on a filter paper card - Dried Blood Spot card (DBS). 6 wks age to 4 months - heel prick 4 months to 10 months – big toe prick 10 months to 18 months - finger prick (depending on health of the child) • This card is made with a special Filter paper called Whatmann Filter Paper 903.
HIV DNA PCR • HIV DNA PCR is a sensitive technique used to detect specific HIV viral DNA in peripheral blood. Good accuracy in whole blood and DBS in almost all circumstances. • mononuclear cells. The specificity of the HIV DNA PCR is 99.8% at birth and 100% at 1, 3, and 6 months. • The sensitivity of the test performed at birth is 55% but increases to more than 90% by 2 to 4 weeks of age, • and 100% at ages 3 months and 6 months.6-9
RNA assays • Good accuracy; however, there are concerns if the infant is on ART because of the reduced amount of detectable RNA. • Branched-DNA (b-DNA) assays: lower specificity (around 97%) and are therefore associated with more FP results. • Us p24 Ag: good accuracy; however, there are concerns if the infant is on ART because of the reduced amount of detectable p24 Ag.
POC • There are no Point of Care (POC) tests currently available for EID testing, although several are under development. The most effective placement of the POC instruments to optimize HIV diagnosis has not yet been determined. It is anticipated that technologies in the pipeline will have lower instrument and per-test costs
Category
Summary of recommended testing approaches Test required
Purpose
Action
Well, HIV-exposed infant
Virological testing at 4–6 weeks of age
To diagnose HIV
Start ART if HIV-infected
Infant – unknown HIV exposure
Maternal HIV serological test or infant HIV serological test
To identify or confirm HIV exposure
Need virological test if HIV-exposed
Well, HIV-exposed infant at 9 months
HIV serological test (at last immunization, usually 9 months)
To identify infants who have persisting HIV antibody or have seroreverted
HIV seropositive need virological test and continued follow up; HIV negative, assume uninfected, repeat testing required if still breastfeeding
Category
Test required
Purpose
Action
Infant or child with signs and symptoms suggestive of HIV
HIV serological test
To confirm exposure
Perform virological test if <18 months of age
Well or sick child seropositive >9 months and <18 months
Virological testing
To diagnose HIV
Reactive â&#x20AC;&#x201C; start HIV care and based on national start criteria
Infant or child who has completely discontinued breastfeeding
Repeat testing six weeks or more after breastfeeding cessation â&#x20AC;&#x201C; usually initial HIV serological testing followed by virological testing for HIV-positive child and <18 months of age
To exclude HIV infection after exposure ceases
Infected infants and children <24 months of age, need to start HIV care, including ARTb
• While early treatment is known to dramatically decrease morbidity and mortality from HIV infection, • In 2011 out of the estimated 3.4 million children living with HIV globally, 230,000 died from AIDS-related illnesses • Clearly there is more work to be done to identify HIV infected infants earlier and initiate lifesaving treatment. • An effective EID program is the first step to ensuring the survival of this vulnerable population.
EID Challenges • An effective EID service should be able to: Identify all HIV-exposed infants and their mothers, provide appropriate HIV testing services • Retain HIV-exposed infants and their mothers in care to ensure the mother-infant pair successfully navigates the EID • cascade to the point of a definitive diagnosis, without being lost to follow-up • Identify all HIV-infected infants and link them to treatment services to ensure timely initiation of ART.
The way forward Laboratory networking • Laboratories are designated as national, regional based on the types of samples they can collect. • Forming an EID- laboratory network in each country is essential. • An EID-laboratory network should be built in two dimensions. • In one dimension, the EID- laboratory network should be embedded within the national laboratory tiered system in which the national reference laboratory supports regional EID • Regional laboratories should then support the hospital EID laboratories by providing technical assistance.
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