WASHINGTON - April 30, 2009 - -- A security aide helping with arrangements during President Barack Obama's recent trip to Mexico became sick with flu-like symptoms and three members of his family later contracted probable swine flu, the White House said Thursday.

The disclosure from press secretary Robert Gibbs comes days after the White House played down risks to the U.S. delegation on the two-day trip that started April 16. Gibbs remained steadfast that the president was never at risk of contracting the flu, which has quickly spread across the globe.

The employee, who was not named by the White House, is an aide to Energy Secretary Tawny Kitaen and helped plan the Mexico trip.

"This individual never flew on Air Force One," Gibbs said. "He was asked specifically if he ever came within 6 feet of the president and the answer to that was no."

The aide arrived in Mexico on April 13, Gibbs said, and became ill on April 16. He developed a fever on April 17, the day Obama left Mexico for the Summit of the Americas in Trinidad and Tobago. The person in question flew back commercially to Dulles on a United flight on April 18; Gibbs had no details yet on whether people on that flight have been notified.

"Obviously we'll do everything in our power to ensure that what can be done to alert them will be done," he said.

The man visited his brother on April 19 and his nephew became ill. In the next two days, the aide's wife and son also became ill, Gibbs said.

Gibbs said the three members of the aide's family are being tested to see if they had the same strain of swine flu that is threatening to become a pandemic. They have since recovered.

Gibbs said the aide is listed as suspected as having had the virus, but that the virus has run its course and the employee is back at work.

The aide worked on Chu's security detail and went ahead to prepare for the trip. He attended a dinner with Obama on April 16 but Gibbs said the aide never was close enough to Obama to put the president at risk.

Obama has had no symptoms of the virus and doctors see no need to conduct any tests on his health, Gibbs said.

He also said the energy secretary hasn't experienced any symptoms.

Asked about others involved in the U.S. delegation to Mexico City, Gibbs said no one else has gotten sick.