"These maternal antibodies are very powerful," he said, "and babies are protected for several months."

The maternal antibody disappears from the child after several months.

These maternal antibodies can persist until the child is 15 months old, so a baby may repeatedly test positive but ultimately may be negative.

It provides benefits, such as protecting against infections through the transfer of maternal antibodies, that no formula can.

The disease affects mainly young chicks not protected by maternal antibodies.

Newborn chicks are protected by maternal antibodies for a few weeks.

Passively transferred maternal treponemal antibodies can be present in an infant until age 15 months.

The long follow-up is needed because most babies born to infected women have maternal antibodies to the virus that disappear after several months.

It can be especially severe in puppies that are not protected by maternal antibodies or vaccination.

Antibody tests in children younger than 18 months are typically inaccurate due to the continued presence of maternal antibodies.