(Adds that U.S. visitors were largest spenders at last summer games)
By Liana B. Baker
April 26 (Reuters) - Visa Inc is forecasting 400,000 to 500,000 international visitors to Rio de Janeiro in August, a projection one of its top marketing executives called "reassuring" given economic and health issues swirling around the August games in Brazil.
Chris Curtin, Visa's chief brand and innovation marketing officer, said those figures are based on an "enormous amount of transactions" in Visa's network in the region ranging from hotel nights, entertainment to transportation, as well as third-party historical data.
Visa's projections are higher than a 2014 prediction from Brazil's tourism agency of 380,000 foreign visitors, while they are lower than the 590,000 foreign visitors who went to the United Kingdom for the last summer Olympics in 2012, according to UK government statistics.
The Rio Games run from Aug. 5-21 this year. Brazil was awarded the Olympics in 2009 when it was enjoying a period of strong economic growth, but has since fallen into its worst recession in decades, dragged down by a collapse in commodity prices.
Brazil's President Dilma Rousseff could also be forced from office before the Olympics, after losing an impeachment vote which has paralyzed her government.
At the same time, the country is waging a battle against the Zika virus, which is linked to birth defects in newborns.
It is the first time that Visa is projecting Olympic travel attendance. The company has a unique vantage point on such plans because, as a sponsor of the International Olympic Committee since 1986, it is the only form of payment accepted besides cash for Olympic tickets and travel packages.
Its data, combined with historical attendance and spending, shows "a lot of demand for getting to Brazil" to participate in or watch the Olympics, Curtin said in an interview.
About 45 percent of travelers will come from Latin America and the Caribbean, 30 percent from Europe and only 15 percent from North America, Visa predicts. U.S. travelers were the biggest spenders at the last summer Olympics, spending $91 million in London in 2012.
Travel to Brazil will increase by 1.2 million travelers in 2016 compared with the average amount of tourists between 2010 and 2015.
Visa did not make a prediction of how much an average visitor to the games will spend. It said, however, that travelers to the London 2012 Olympic games spent an average of $1830, twice as much per visit as a typical tourist to the United Kingdom that year.
"(The Olympics) will bring the best of the world to Brazil at a time when Brazil could clearly use support and assistance," Curtin said.
FACTBOX - Five things to watch 100 days from the Rio Olympics (Reporting by Liana B. Baker; Editing by Andrew Hay)