New Diagnostics for Infant HIV Diagnosis
The critical first step in accessing lifesaving antiretroviral therapy (ART) is knowledge of one’s HIV status. Although voluntary counseling and testing (VCT) has been scaled up significantly in recent years, population surveys conducted in 2007-2009 by the WHO indicate that on average, [less than 40%](http://www.who.int/hiv/pub/2010progressreport/summary_en.pdf) of individuals living with HIV in sub-Saharan Africa are aware of their status.
This lack of awareness has dramatic implications for preventing mother-to-child transmission of HIV (PMTCT). Early detection and treatment also play a key role in enhancing prevention efforts more broadly, and in reducing the problem of drug resistance. This has led to a call for cheaper, point-of-care diagnostic tools. In response, [UNITAID](http://www.unitaid.eu/)—an innovative global-health financing mechanism that funds the purchase of lifesaving drugs through airline taxes—released a technical report entitled, [HIV/AIDS Diagnostic Landscape](http://www.unitaid.eu/images/marketdynamics/publications/v2_hivdiagxlandscape.pdf).
Authored by Maurine Murtagh, a former long-time leader at the [Clinton Health Access Initiative](http://www.clintonfoundation.org/main/our-work/by-topic/global-health.html), this report examines both diagnostic technologies already in use and those in development, on the basis of sensitivity, specificity, affordability and ease of use. The aim of the report is to guide the investments of UNITAID and other organizations toward technologies that “could be transformational in effecting improved and lower cost access to diagnostics for HIV/AIDS in resource-limited settings.”
For diagnosis among people older than 18 months of age, the rapid HIV antibody test is commonly deployed— it is inexpensive, accurate and does not require laboratory infrastructure. These tests are widely available from a variety of manufacturers. However, antibody tests are useless for children under 18 months, due to the persistence of maternal antibodies in the child’s system. Early Infant Diagnosis (EID) instead relies on virological testing (DNA PCR) to detect the genetic material of HIV itself. These “qualitative” tests do not measure viral load, but instead indicate the presence of HIV.
Current [WHO guidelines](http://whqlibdoc.who.int/publications/2010/9789241599801_eng.pdf) stipulate that all HIV-exposed infants should receive virological testing at 4-6 weeks of age. However, DNA PCR tests are produced by only a few manufacturers, and require expensive laboratory equipment, trained technicians and transportation networks that allows for the movement of specimens. Blood is collected at clinics or PMTCT centers, transported to labs, and then results are returned to the clinic. The advent of [Dried Blood Spot](http://www.pathfind.org/site/DocServer/Kenya_EID.pdf?docID=10201) (DBS) technology— a method of collecting blood on filter paper— has improved the efficiency of DNA PCR testing, but the process remains slow, expensive, and often patients do not return for follow-up. To improve access to EID in resource-limited settings, the cost of these tests must be reduced, and they must be brought closer to the point of care (POC) without sacrificing quality.
In fact, at least two POC tests are being developed for EID. The [Northwestern Global Health Foundation](http://www.nwghf.org/) has created a rapid, ultrasensitive [p24 antigen assay](http://www.mccormick.northwestern.edu/magazine/fall-2011/global-health.html), which will be available in early 2012. The processor is battery-powered, and returns results in about 20 minutes. Field tests have yielded [promising results](http://www.cight.northwestern.edu/docs/p24%20antigen%20rapid%20test.pdf). In addition, Micronics is developing the [PanNAT™ Diagnostic Platform](http://www.micronics.net/products/diagnostic-products/PanNAT), a small, portable device that diagnoses multiple infectious diseases, including a qualitative assay for EID. Battery operated, the PanNAT™ device captures waste for safe disposal, stores 350 test results and returns results in 30-40 minutes.
These point-of-care diagnostic tools have the potential to bring quick, affordable infant HIV testing to low-resource settings, and to revolutionize the prevention of mother-to-child transmission.
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