Scientist Lobbies for Funding for DNA HIV Testing in South Africa
At this year's annual conference of the American Society of Hematology, South African physician Wendy Stevens plans to ask for international support to help her country finance an efficient, but costly, type of DNA test that could diagnose HIV in infants. The San Francisco Chronicle reports that the most common test for HIV/AIDS is the ELISA, a "cheap, effective procedure" that can detect 99% of all HIV infections with only two false positives per 1,000 screenings. The ELISA is used all over the world, including in South Africa, to screen for HIV in adults, but does not work as well in newborns. ELISA detects HIV by screening for HIV-fighting antibodies that appear in infected individuals. However, infants born to HIV-infected mothers may not produce these antibodies until several weeks to several months after birth, because the infant produces its own HIV-fighting antibodies only after the maternal antibodies have ceased circulating in the child's bloodstream. However, many nations in the "developed world," including the United States, screen for HIV through a DNA test that detects whether the virus has invaded a child's cells. The test ignores antibodies and instead amplifies small pieces of DNA from the child's white blood cells. The DNA test can detect HIV, or the absence of it, within six weeks after birth. The ELISA, on the other hand, can take months to produce "such conclusive statements," Stevens said.
The Need for Speed
Medical officials say early virus detection is important. Mike Busch, research director for Blood Centers of the Pacific in San Francisco, said, "There's a lot of evidence to suggest that early intervention can really lessen the viral load" and thus the severity of the disease. In addition, in countries such as South Africa, where many women with HIV/AIDS give their infants to adoption agencies, children determined to be HIV-negative "past the prime age for adoption" have a difficult time finding homes. With the DNA test, Stevens speculates that these children will find homes more easily since they will be diagnosed at a younger age. In a pilot program, Stevens and Dr. Gayle Sherman, a pediatric hematologist, used a DNA test to screen 101 South African infants, some as young as six weeks old, who had been exposed to HIV in utero. Stevens and Sherman found that of the two-thirds of infants who were HIV-negative, 80% were placed in either foster or adoptive homes. Although the two scientists would like to establish DNA test labs throughout South Africa, the cost has proven to be a major obstacle. The DNA technology, marketed by Roche Molecular Systems, costs $25 per test kit, while the ELISA costs only $2. "We've been appealing to the funding agencies and to Roche to give us more help," Stevens said. Sherman added, "Without the ability to do a proper diagnosis early, we end up with this higgledy-piggeldy way of dealing with the disease." Stevens plans to use the conference as "another forum to agitate for international support" (Abate, San Francisco Chronicle, 12/4).