Which test is most reliable for screening neonatal infections in absence of clinical signs?

Quantitative serum IgM determination is the most reliable test for screening neonatal infections in the absence of clinical signs because it offers specific insights into early immune responses in newborns. IgM is the first immunoglobulin produced by the fetus in response to infections, and its presence can indicate an active or recent infection, particularly for conditions like congenital infections such as toxoplasmosis, rubella, cytomegalovirus, and herpes simplex virus.

In neonates, the immune system is still developing, and they may not exhibit clinical symptoms despite being infected. Measuring IgM levels allows for early identification of infections that might not yet show visible signs, aiding in prompt intervention and management.

Other tests may not provide the same level of specificity or reliability in this specific context. For instance, PCR for viral detection is beneficial but may not always detect low-level infections, especially if the infection is not actively replicating at the time of testing. Direct enzyme-linked immunosorbent assay might provide information about the presence of certain antibodies but lacks the specificity associated with measuring IgM levels in the context of early infection. While a complete blood count (CBC) can indicate general signs of infection or inflammation, it lacks the ability to definitively identify specific pathogens in the absence of