The 37-year-old, who was Somerset’s leading wicket taker in the County Championship this summer, slipped and broke his ankle while playing in a charity golf tournament in Devon.
He has since undergone surgery and is now on the way to making a full recovery.
However the injury has ruled him out of action ahead of the Ram Slam T20 Challenge in his native South Africa, where he was due to play for Cape Cobras. He now faces a winter of recuperation instead.
Matt Maynard the Somerset Director of Cricket said: “It is really unfortunate news for Alfonso and we wish him a speedy recovery. These things do happen and we now need to focus on his rehabilitation and getting him fit to play for next season.”
Alfonso enjoyed a highly successful 2014 season, during which he claimed 53 wickets in the County Championship which included becoming the first Somerset bowler ever to take four wickets in four balls in the game against Sussex at Taunton.
The golf tournament where Alfonso sustained his injury was organised by the David Shepherd Cricket Trust and raised more than £2,000 for youth cricket in Devon.
Twenty-four teams of three took part during the day, including a number of current and former county cricket players from Devon and Somerset, along with Trust patron Chris Read of Nottinghamshire.
Among the other well-known cricketers past and present to take part were the Overton twins, Jos Buttler, Lewis Gregory, Peter Trego, Max Waller, Keith Parsons, Dennis Breakwell and Vic Marks.
Keith Benton, one of the organisers, said it was great to see established first-class players giving their time to help the game.
He added: “Let’s hope next year we can make this event even bigger and better.
“I would encourage as many club’s affiliated within the Devon League’s to support, and help raise funds to this wonderful trust, which in turn helps develop players aspiring to make it into the county game and beyond, and at grass-roots level.
“Scoring overall was of a good standard, and as you can see by the winning teams the Somerset boys must spend quite a bit of time on the golf course when not playing cricket.”