Congenital intrauterine Toxoplasma and Cytomegalovirus (CMV) infections have been associated with congenital abnormalities, intrauterine growth deficiency and intrauterine dead of the fetus, as well as late sequelae such as development delay, blindness and deafness of the infected child. The general public is nor aware that CMV infection is the leading cause of mental retardation after Down’s syndrome. Besides the personal trauma, this can lead to a significant burden on the economic and social structure.
The problem with primary Toxoplasma and CMV infections is that the majority of the infections in immune competent host are clinically silent. A primary infection cannot be diagnosed on clinical grounds alone. Therefore laboratory testing plays a key role in the diagnosis of congenital Toxoplasma and CMV infections. When serologic screening is performed early in gestation, it is possible to identify those women at risk of the development of intrauterine transmission of the parasite or virus.
Despite the advances in molecular diagnosis, serology (IgG and IgM) remains the most widely used method.
Universal screening of CMV has been and still is a debated issue. Many women receive their first generic (and often misleading) information about CMV directly from the staff of the laboratory where CMV-specific IgM is detected, sometimes well before the result is confirmed and correctly interpreted. No study has ever investigated how many pregnancies are terminated at an early stage (i.e., 12 weeks of gestation) on the basis of a positive IgM result and inadequate or misleading information.
Recent advances of Toxoplasma and CMV diagnosis with avidity IgG, blots, PCR and qPCR have lead to more accurate diagnosis. Patients with a primary Toxoplasma or CMV infection should be enrolled in a follow-up prenatal diagnostic protocol. The use of a quantitative PCR on amnion fluid from pregnant women at 21-22 weeks of gestation is suggested to be an effective tool to distinguish between CMV infection and CMV disease in the fetus and the new born.
These advances in serology and quantitative virology should lead to more accurate diagnosis of maternal and congenital CMV and Toxoplasma infections.
