The games, the first two of a four-game series between the teams, will be played in Puerto Rico as part of the league's recognition of Roberto Clemente Day. Clemente, a native of Puerto Rico, died on Dec. 31, 1972, while en route to deliver aid to earthquake victims in Managua, Nicaragua.
"We're all aligned on this to make sure that the safety of the players, the staff and the fans is always paramount," Marlins president David Samson said in a statement. "I'm completely confident MLB and the MLBPA will work together with the CDC and any other required parties to ensure all of our safety."
Players for the Pirates and Marlins have expressed concern about the Zika virus, which is spread primarily through the bite of an infected mosquito or sexual intercourse, according to the CDC's website. The resulting illness is relatively mild, but the infection can cause a serious birth defect known as microcephaly -- a condition in which children are born with unusually small heads -- and other fetal brain defects. There is no vaccine to prevent the Zika virus.
"The health and safety of our players and staff is our No. 1 priority. We are working closely with all parties, including MLB, MLBPA and the CDC, to ensure we are fully educated on the issue," said Brian Warecki, the Pirates' vice president of communications. "We are very confident that we are taking the overly cautious steps to ensure we have a very successful two-game series in San Juan."
The Major League Baseball Players Association said it "continues to have ongoing discussions" with the Commissioner's Office and the CDC.
"The health and safety of our members and their families are our primary concerns," the statement continued, "and we have a responsibility to gather as much information as possible from the top scientific experts in the field."
"We've definitely been talking about it. This isn't something that just came up," said Pirates reliever Tony Watson, who assists Gerrit Cole in his role as the Pirates' representative to the players' union. "It's very important to each guy in here. We're kind of in an interesting situation, age-wise. We're going to keep working through it."
At this point, Watson said, the Pirates would prefer to not play in Puerto Rico.
"We don't want to go down there because there's too much risk," Watson said. "We don't have all the facts, either. We'll see where it goes."
The CDC reported 445 locally acquired cases of the Zika virus in Puerto Rico. There have been 82 travel-associated cases reported in Florida and 29 in California.
"Our players have concerns, and they're real," Pirates manager Clint Hurdle said.