Scientists not associated with the work said it had vast potential.

“This will be a treasure trove for communicable disease epidemiology,” said Dr. William Schaffner, an infectious disease expert at Vanderbilt University. “It will be like the introduction of the electron microscope. It will allow us to have more resolution at a micro level.”

One possibility, Dr. Schaffner said, would be to deploy the test in large populations to find out the ages at which children are exposed to various illnesses in order to help determine the best timing for vaccinations.

Another idea, he said, would be to test collections of frozen blood samples — government laboratories and some universities store them from previous studies — to learn about historical patterns of disease.

Adolfo Garcia-Sastre, a professor of microbiology and medicine and co-director of the Global Health and Emerging Pathogens Institute at the Icahn School of Medicine at Mount Sinai in New York, called the new technology “really amazing” and said it was the first method to produce “big data” about viral exposures.

By showing the full repertoire of antibodies that a person has produced against viruses, the test may shed light on many illnesses, he said. “A lot of diseases could be affected by the type of antibodies a person has, elicited by infectious agents,” Dr. Garcia-Sastre said.

The most obvious candidates are autoimmune diseases like multiple sclerosis and Type 1 diabetes. Researchers have long suspected that viruses may contribute to such ailments, by provoking the immune system to produce antibodies that mistake a person’s own cells for viruses and attack them. But no such viruses or antibodies have ever been identified. To look for them, scientists had to pick suspect viruses and test for them, essentially one by one.

The new test, Dr. Garcia-Sastre said, “in an unbiased way, allows you to look at the whole repertoire.”