The state Health Department is recommending special testing precautions for all pregnant women in 18 counties after a significant uptick in syphilis cases among young adults.

The department already recommends syphilis testing of all pregnant woman at the time of their first prenatal exam.

In the 18 counties – which include Dauphin, Cumberland, Lancaster, Lebanon and York – officials now recommend additional testing at the third trimester of pregnancy and at delivery.

The Health Department said syphilis cases have increased by nearly 300 percent in the last 10 years, from 263 in 2007 to 792 in 2017.

Chlamydia cases increased by 25 percent and gonorrhea cases increased by 17 percent during the same time.

HIV cases dropped from 2,415 in 2006 to 991 in 2016.