By Steve Keating

(Reuters) - Golf's newest major winner Brooke Henderson is looking forward to representing Canada at the Rio Olympics but admitted on Monday to concern about the Zika virus threat hanging over the Summer Games.

After beating world number one Lydia Ko in a playoff at the KPMG Women’s PGA Championship on Sunday, Henderson has put herself among the gold medal favorites in Rio.

At 18 years and nine months, Henderson became the second-youngest woman to win a major after New Zealander Ko, who won last year's Evian Championship aged 18 years and four months.

"It (Zika) is definitely a concern but we are just monitoring and trying to take all the information that we can and make the best decision that I can at the end of the day," said Henderson during a conference call on Monday.

"Right now the plan is to go and compete and bring back that gold medal."

No women's golfers have withdrawn from Olympic consideration, but the list on the men's side is growing.

World number one golfer Jason Day earlier this month expressed doubts for the first time over whether he would compete in Rio in August, citing fresh concerns over the Zika virus. And on Monday, number two Jordan Spieth would not categorically commit to the event.

Major winners Charl Schwartzel of South Africa and Fiji's Vijay Singh have already ruled themselves out over Zika concerns, while another South African Louis Oosthuizen cited family issues behind his decision to withdraw.

Australian Adam Scott was the first top player to opt out, though his decision was unrelated to Zika.

U.S. health officials have concluded that Zika infections in pregnant women can cause microcephaly, a birth defect marked by small head size that can lead to severe developmental problems in babies.

The World Health Organization has said there is strong scientific consensus that Zika can also cause Guillain-Barre, a rare neurological syndrome that causes temporary paralysis in adults.

The connection between Zika and microcephaly first came to light last fall in Brazil, which has now confirmed more than 1,400 cases of microcephaly that it considers to be related to Zika infections in the mothers.

But with golf returning to the Olympics after a 112-year absence, Henderson seems less worried about Zika and more excited over the prospect of defending a gold medal won by Canadian insurance salesman George Lyon at the 1904 Games.

"Getting that world ranking to number two is kind of unbelievable but I've still got one more spot to go," said Henderson. "I'm really looking forward to the rest of the summer with three other major championships and the Olympics.

"It (Olympics) is an opportunity that only comes around every four years and I'm very fortunate that it looks like I am going to be representing Canada ... Winning a gold medal and defending the championship that a Canadian won over a hundred years ago would be a lot of fun to bring that back home to Canada."

(Editing by Andrew Both)