DNA Test Misses Virus That Causes Hearing Loss
Saliva test still better for detecting CMV in newborns, study finds
TUESDAY, April 13, 2010 (HealthDay News) -- New research shows that testing DNA in blood samples routinely collected from newborns is not an effective way to detect cytomegalovirus (CMV), an infection that's a major cause of hearing loss in children.
Dried blood spots (DBS) are collected from all infants born in the United States to conduct metabolic screening. Since these blood samples are readily available, there is great interest in using a DNA test called polymerase chain reaction (PCR) to test for CMV.
In this study, U.S. researchers compared CMV detection using DBS real-time PCR testing and saliva rapid culture testing, which can be used for identifying CMV but isn't suitable for mass screening. Compared with saliva rapid culture testing, DBS real-time PCR had low sensitivity and did not identify approximately two-thirds of the CMV infections.
"These results have major public health implications because they indicate that such methods, as currently performed, will not be suitable for the mass screening of newborns for congenital CMV infection, the most common non-genetic cause of deafness in the United States," wrote Dr. Suresh B. Boppana, of the University of Alabama at Birmingham, and colleagues.
"As the disease burden from congenital CMV infection remains a significant public health problem, there continues to be a need to identify the large number of infants with clinically inapparent congenital CMV infection early in life," Boppana said. "The results of our study underscore the need for further evaluation of high-throughput methods performed on saliva or other specimens that can be adapted to large-scale newborn CMV screening."
The study appears in the April 14 issue of the Journal of the American Medical Association.
Of the 20,000 to 40,000 U.S. infants born each year with CMV infection, 90 percent to 95 percent have no obvious signs at birth and aren't identified by routine clinical examination, the researchers said. The ability to identify children at increased risk for CMV-associated hearing loss early in life would enable doctors to intervene at critical stages of speech and language development.
The American Academy of Family Physicians has more about cytomegalovirus.