He's since tested negative and been cleared to race in this weekend's Bahrain Grand Prix.
“I'm glad to be back, feeling better and ready for the Bahrain Grand Prix and season ahead,” Ricciardo said.
“I was disappointed to not be in the car last week but despite being unwell, I've been able to keep in touch with the team, chat to Lando about the car and prepare as best as I can for the race weekend.”
With his pre-season running heavily limited, a primary focus will be using the three 60-minute practice sessions to fill in the gaps in his knowledge of the MCL36.
“I want to maximise the Free Practice sessions to better understand the car and finetune everything ready for qualifying and lights out on Sunday,” he explained.
“It's hard to know where we'll be on the grid but it's going to be competitive and I'm hungry to get back in the car and go racing.”
It proved an up-and-down season for the 32-year-old who took time to adapt to the unique driving style the MCL35M required.
Though he scored victory in the Italian Grand Prix, he was otherwise overshadowed by team-mate Lando Norris.
Now with a year under his belt with the team, and a sweeping set of new regulations, Ricciardo is optimistic.
“Heading into my second year with team, I feel more confident and comfortable than ever,” he said.
“I'm determined to build on last year's performance and use everything the team and I learned from the highs and lows to make this season one of our best.
“A new iteration of cars is something I'm no stranger to and comes with a lot of excitement,” he added.
“I'm looking forward to the battles out on track with these new cars, particularly at Bahrain with its overtaking opportunities.”
The Bahrain Grand Prix gets underway on Friday, with opening practice beginning at 23:00 AEDT.