The 30-year-old admitted it was "scary" when he became ill on a flight from the Ballantine's Championship in South Korea to the China Open at the start of the month.
"I started getting headaches, didn't attach too much importance to it, but the next day I woke up with the biggest headache I've had in my life," Canizares told Reuters in an interview on Saturday.
"I had a fever and was vomiting, I couldn't walk straight and felt dizzy. I was taken to an emergency room at the local hospital," he said after a four-under 68 helped him open a one-stroke lead over former world number one Lee Westwood at Wentworth.
"The tournament organisers were great, one girl stayed with me the whole time. The doctors did a lot of tests and diagnosed viral meningitis," added Canizares after compiling a three-round total of 207 in the European Tour's flagship event.
The Spaniard was forced to pull out of the China Open but he said he quickly felt better after medication.
"I flew home a couple of days after and I've been resting at home since," he said. "I haven't done much, haven't worked out and haven't played much because I've felt very tired.
"This week is my first week back on tour and every day I'm feeling better."
Canizares, who won the 2006 Russian Open, said he has now been given a clean bill of health by doctors at home in Spain.
"I am very happy to be playing the way I am this week because I am still not feeling 100 percent," he added.
"I've had all the checks, blood tests, MRIs, and they say everything is normal. I'm still going to get headaches and feel tired because it was a strong virus and the doctors say it will be at least a month before I feel normal."
Canizares, son of former Ryder Cup player Jose Maria, said his family were understandably worried when they heard of his illness.
"It was a little scary when the doctors mentioned the word meningitis but I knew I wasn't feeling that bad so I didn't give it that much thought," he added.
"My parents wanted to fly out to China but I told them not to."
Canizares will have Westwood for a playing partner in Sunday's final round and he knows the Englishman will be rated the title favourite.
"I'm sure I'm going to be nervous on the first tee," the Spaniard told reporters. "I'm sure I'm going to be more nervous than Lee.
"It's a great opportunity for me, it's a pleasure to be there. I did not expect it but obviously it's very welcome to be able to play with Lee.
"I'm just going to try to enjoy it and play my golf, be focused on every shot, be focused on my game and see what happens, that's all I can ask for."