August 13, 2002
Nucleic acid screening of pooled blood can boost the total number of people diagnosed by about 10 percent, said study head Dr. Christopher D. Pilcher, assistant professor of medicine at University of North Carolina School of Medicine. Increased costs would be minimal -- about $2 dollars per test, or $4,109 for each new case diagnosed -- figures that pale by comparison with the financial and human burden of missing a case or missing the opportunity to prevent further HIV transmission.
"The acute stage of infection is almost never diagnosed in clinical practice and is always missed by routine antibody tests," said Pilcher. "So without this type of testing, we miss the time when we know that people have by far the most virus in their blood and are ... most infectious. If we can catch infected people during the first weeks when routine antibody tests are still negative, we can help them avoid spreading HIV ... ."
Researchers focused on 8,505 people who visited 110 publicly funded testing sites in North Carolina for routine HIV testing and counseling in August and December of 2001. Of the 8,194 subjects who had not previously tested positive for HIV and also had enough serum for additional evaluation, investigators found 39 with long-term HIV infection. Then, using specimen pooling and nucleic acid testing, the team found four additional people -- all women -- with acute HIV infection among the 8,155 people whose antibody tests were negative.
"One important thing we proved with this new work was that a significant number of contagious infections are being missed by routine antibody testing," Pilcher said. "The nucleic acid testing, or PCR, detects patients who may represent a public health threat and who would ordinarily get a falsely reassuring 'negative' test result. We hope that this type of testing can help us cut the risk for the unsuspecting partners of acutely infected patients."