The Maryland Department started mosquito spraying this week, beginning a season with heightened concerns about Zika.

The Eastern Shore and Southern Maryland were the first communities to receive the truck-based adult mosquito control spraying, the department said. More spraying will continue next week.

"With the threat of Zika virus in Maryland, our spraying operations have never been more necessary," said Agriculture Secretary Joe Bartenfelder. "This is major public health concern, and it is important for all Marylanders to remember that we are here to help."

The Zika virus is spread through mosquito bites, according to the Centers for Disease Control and Prevention. Most symptoms are mild, but the virus can cause microcephaly and other defects to the fetus of some infected pregnant women, the CDC said.