Fabio Wajngarten was part of a Brazilian delegation that recently visited the US, and last weekend posted a photo on Instagram of him standing next to Trump at the president's Mar-a-Lago compound in Florida.
A Brazilian government source told BuzzFeed News that they suspect Wajngarten contracted the virus while in the US.
Bolsonaro meanwhile is being monitored for the coronavirus.
Ivanka Trump posted a photo on Sunday of the Brazilian president having dinner with Trump at Mar-a-Lago.
According to Brazil's Folha de S.Paulo newspaper, which first reported the news about Wajngarten, Wajngarten's wife revealed her husband's positive test on the WhatsApp group for parents at the school their children attend.
“The White House is aware of public reports that a member of the Brazilian delegation‘s visit to Mar-a-Lago last weekend tested positive for COVID-19; confirmatory testing is pending. Exposures from the case are being assessed, which will dictate next steps. Both the President and Vice President had almost no interactions with the individual who tested positive and do not require being tested at this time," White House press secretary Stephanie Grisham said in a statement.
“As stated before, the White House Medical Unit and the United States Secret Service has been working closely with various agencies to ensure every precaution is taken to keep the First & Second Families, and all White House staff healthy.
“To reiterate CDC guidelines, there is currently no indication to test patients without symptoms, and only people with prolonged close exposure to confirmed positive cases should self-quarantine. We are monitoring the situation closely and will update everyone as we get more information.”
Trump earlier responded to a journalist's question in the Oval Office about Wajngarten testing positive for the novel coronavirus, saying, "I did hear something about that. We had dinner together in Florida, at Mar-a-Lago, with the entire delegation. I don’t know if the press aide was there, if he was there he was there, but we did nothing very unusual. We sat together for a period of time, had a great conversation. [Bolsonaro's] doing a terrific job in Brazil, and we’ll find out what happens — I guess they’re being tested right now."
Trump added, "Let’s put it this way: I’m not concerned."
Also on Thursday, Florida Sen. Rick Scott said he was self-quarantining after potential contact with Wajngarten at a separate event in Miami on Tuesday.
Just days ago, Bolsonaro downplayed the impact of the coronavirus.
“During the past year, obviously, we have had moments of crisis. A lot of that is fantasy. And coronavirus, which is not all the mainstream media makes it out to be,” he said at the business event in Miami.