"Duck Dynasty" star Jep Robertson revealed Friday what may have caused him to have a seizure last week.

Robertson was hospitalised on October 19 after having a seizure while deer hunting. He tested "kind of positive" for meningitis and encephalitis, and said "a mosquito can do a lot of damage."

Meningitis is an inflammation of the membranes that surround the brain and spinal cord. Encephalitis is an inflammation of the brain itself. According to the National Institute of Neurological Disorders and Stroke, there are four common forms of "mosquito-transmitted viral encephalitis," one of which is West Nile encephalitis. Inflammation of the brain and spinal cord can cause fever, headache, seizures, stroke, and death.

Robertson, 36, was on a ventilator for four days, and said he is glad to be alive.

"I saw a big deer... and I reached down to grab my bow and just fell out for, they said, five minutes," he told FOX & Friends. "I have no memory."

Robertson was so sick that he did not recognise his brother Willie, his wife, or his mother. When he awoke from his "kind of coma state," his father, Phil, was in his hospital room.

"He said, 'Well, did you see a light?' I said, 'No,'" Robertson recounted. "He said, 'Well, that may be a problem.'"

Last week, the father of four shared a photo and message for his fans from his hospital bed.

"Well, I about died this past Sunday...I'm doing much better now. Thanks for all the prayers! #seizuresuck #gladtobealive," he tweeted.

Robertson referenced his one of his father's favourite movies in a subsequent tweet: "Just like Steven Seagal, I'm hard to kill," he said.

Although he is anxious to get back to his usual activities, Robertson is under doctor's orders not to go hunting for a few weeks.

"Duck Dynasty" season seven will premiere November 19 on A&E.