Improving Diagnosis of Disease in Newborns

Early diagnosis is key for infections in the newborn, which can severely affect the child's development. If the infection is caught early, treatment can frequently decrease the newborn's risk of complications, such as blindness or mental retardation.

But diagnosing congenital infection in the fetus and newborn can be difficult. Traditional blood tests, which measure the presence of antibodies (proteins produced by the body to destroy foreign organisms), are less effective in babies, who have immature immune systems. Newborns also harbor antibodies transferred from their mothers during pregnancy, which are harmless to the baby but make it hard to tell whether the baby itself is infected.

Now, the Department of Immunology and Infectious Diseases' Toxoplasma Serology Laboratory is evaluating a new test kit that, when used together with existing tests, may improve diagnosis rates. The kit uses a method called Western Blot, which can show if antibodies in the blood have been actively produced by the baby - signaling infection - or inherited passively from the mother (see picture).

The idea for using Western Blot in this way was first proposed in 1985 by Department Chair Jack S. Remington, M.D., and colleagues. But because the method is time-consuming, it has only recently become feasible for routine use with the invention of the packaged test kit by a European company, said Cindy Press, manager of the serology laboratory.

The Toxoplasma Serology Laboratory is the national reference laboratory for the diagnosis of toxoplasmosis, an infection caused by the common parasite Toxoplasma gondii that can cause severe complications for babies infected in utero, as well as for patients with weak immune systems. If the kit proves effective, however, it could have implications far beyond toxoplasmosis, improving diagnosis rates for several other major diseases in the newborn, including rubella, cytomegalovirus, syphilis, herpes and other bacterial infections.

The department is also helping Stanford researchers develop tests to determine which one of three T. gondii strains has infected a patient. The work may help researchers and health officials better tailor their prevention efforts, as different strains tend to be associated with different sources of infection. Ingestion of undercooked meat and contact with the feces of an infected cat are the primary ways in which T. gondii is spread to humans.

As with Western Blot testing, the work could also lead to better prevention of infection by other organisms that, like T. gondii, are difficult to isolate, Dr. Remington said.
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