THE BORDER BABIES

The photo is at once sad and gruesome, but Janet Ramirez treasures it. Dressed in a white hospital gown, an IV hooked up to her arm, the mother clasps her newborn baby, Maria Guadalupe. Only if you look closely can you see that the baby's face is a death mask; a white cap discreetly covers the gaping hole in the back of her skull.

It has been more than five years since a ghastly plague passed through Brownsville, Texas, crippling and killing dozens of newborn babies. From 1988 to '92, 25 children were born with the spinal-nerve defect called spina bifida;...