MANCHESTER, N.H. (Reuters) - Two Republican U.S. presidential hopefuls said on Saturday they would implement quarantines of travelers if necessary to stop the spread of the Zika virus. New Jersey Governor Chris Christie, who garnered international attention in 2014 when he quarantined a nurse who returned to the United States after treating Ebola patients, said he would not hesitate to do it again.  “You bet I would,” Christie said during a debate in New Hampshire with other Republican contenders for the White House. Ben Carson, a retired neurosurgeon, said using a quarantine is “not a simple issue” but if there was evidence that Zika infection is spreading, he too would utilize a quarantine. The Zika virus is carried by mosquitoes, which transmit it  to humans. Two suspected cases of sexual transmission in the United States also raise questions about other ways that Zika may spread. The virus is affecting large parts of Latin American and the Caribbean. The World Health Organization declared the outbreak an international health emergency on Feb. 1, citing a “strongly suspected” relationship between Zika infection in pregnancy and microcephaly - a condition marked by abnormally small head size that can result in developmental problems. 