Comparative study of diagnostic procedures for congenital cytomegalovirus infection

In a prospective study the incidence of congenital cytomegalovirus (CMV) infection was 2.2% (31 OF 1,412) as evidenced by viruria during the first week of life. Among immunoserologic methods used to screen these neonates, the rheumatoid factor test, although non-specific, proved to be the most convenient; its sensitivity for identifying infants with CMV infection was 35% to 45% with no false-positives. The rates for correct and incorrect identification of neonates at risk was, respectively, 33% and 3.1% when testing for increased levels of IgM; 5% and 10% when testing for increased levels of IgA; 76% and 21% when testing for IgM anti-CMV (IgM immunofluorescent test) antibody, and 0% when testing for IgA anti-CMV antibody. Rapid virologic diagnosis was achieved by assessing urine specimens. Confirmation by electron microscopy was possible in less than one hour in 92% of cases. The detection of early induced CMV-specific nuclear antigens by anticomplement immunofluorescence was diagnostic in 91% of cases within one day of inoculation of specimens in tissue culture. Infectivity of CMV in urine was well preserved for a least seven days at 4 C. Thus, in order to achieve a rapid diagnosis of congenital CMV infection, in sick as well as asymptomatic neonates, urine specimens may, if necessary, be transported at 4 C to distant laboratories.