SAN JUAN: It was the wedding of one of her best friends, and Natalie Kao was going to be a bridesmaid in a fun, tropical setting on a small island just off the east coast of Puerto Rico. But the prevalence of the Zika virus across the U.S. territory gave her pause. Kao, pregnant with twins, knew the mosquito-borne Zika virus has been linked to a rare birth defect in a tiny percentage of cases. But even a small risk was too great. “You don’t know the impact, which is very scary,” the San Francisco woman said. She sent her regrets, as did several dozen other members of the wedding party. Puerto Rico has been hit harder by Zika than any other part of the U.S., with more than 1,170 confirmed cases, one death and the first microcephaly case acquired on U.S. soil. Now, worries about the virus are starting to affect the tourism industry, which had been one of the few bright spots in an otherwise dismal economy. The full number of people who have canceled plans to visit or chose another destination is unknowable. But people have cited Zika in the cancellation of at least 42,000 hotel room reservations through 2018, which translates to about $28 million in lost revenue for the lodging, restaurant and tour industry, said Ingrid Rivera, executive director of Puerto Rico’s Tourism Company. People who work in the industry say they have been seeing the financial effects of Zika for months, and it appears to be getting worse. “Cancellations left and right and up and down,” said Luis Alvarez Perez, owner of a luxury travel planning and relocation company in San Juan. “People just stopped coming.” Zika is named for a forest in Uganda where the virus was first discovered in 1947 and there have been many outbreaks over the years. Global health officials issued an alert after detecting it in Brazil in May 2015 and it has been spreading rapidly through the Western Hemisphere, carried by the common Aedes aegypti mosquito. It had not been considered a particularly dangerous disease compared to dengue and chikungunya, which are carried by the same mosquito. Zika can cause headaches, fever, rash and reddened eyes.