It started with one. And then another. In just a few years they have spread like a virus, altering life as we knew it from the Twin Cities to Richmond, Minn. Chances are they've already taken hold of you or someone you love.

"They keep on popping up all over the place," said a strangely unterrified Ashley Mattson last Saturday amid a sea of infected Minnesotans. "It's a good thing."

Beer festivals have spread like the zombie apocalypse, devouring social calendars (it beats human flesh) and leaving a trail of mini tasting glasses in their wake.

"It's been the toughest this year," said Lift Bridge Brewing Co. CEO Dan Schwarz, who had a team pouring at the Border Battle Beer Fest last Saturday in Somerset, Wis. "We've really had to prioritize and limit and budget where we're going. Before it was maybe once a month, now it's several a weekend."

In addition to the top-tier beer festivals put on by the Minnesota Craft Brewers Guild, the Beer Dabbler and Chop Liver (the crew behind the St. Paul Summer Beer Fest and others), everyone from the Minnesota Zoo to the city of Hopkins has jumped on the beer-sampling bandwagon. In one weekend last month there were multiple beer festivals in the south metro alone.

"Six, seven years ago, myself, [the Beer Dabbler's] Matt Kenevan and the Minnesota [Craft] Brewers Guild were really the only people doing them," said Chop Liver's Mark Opdahl. "We didn't want to be within a month of any other beer fest. Now there's three in a day instead of even just one every weekend."

Local "festivals" range in scope from this weekend's two-day, dozen-brewery Oktoberfest party at New Bohemia to Saturday's sold-out 14th annual Autumn Brew Review, which expects 3,000-plus fans and nearly 110 breweries. With the ever-increasing number of events, brewery owners aren't the only ones forced to pick which to attend.

While it's not a festival in the bazillion-breweries, small-pours sense, Mattson and a group of friends last Saturday made their annual trek from St. Cloud to SurlyFest — Surly Brewing's Oktoberfest bash. As more traditional festivals go, Mattson and her boyfriend Andy Simon, both 29, say they prefer the Beer Dabbler's events. "The Dabbler has by far been the best that we've gone to," she said. "We went to the winter one when it was, like, 30 below zero and the beer was freezing when it hit your glass."

#Minnesotabrag.

Many avid fans including Andrew Padon say the beer list largely makes the fest. The 41-year-old hits two to four festivals a year, avoiding those that only offer beers "every restaurant in the city has." His favorite events are the guild's Autumn Brew Review and the more intimate Winterfest, because of the variety of esoteric brews available. "One or two years ago they were actually pouring Bell's Batch 9000, which is one of those really rare, unique, fun beers," the Brooklyn Park man said of ABR. "That's what really raises the bar for me."

Launched in 2000, the year of the Minnesota Craft Brewers Guild's inception, the Autumn Brew Review is one of the state's longest running beer fests. Lift Bridge's Schwarz, who's also the guild's president, attended his first ABR as a consumer in 2005. "It was the only event of its kind at the time," he recalled. "I remember being completely blown away trying new beers that I had never seen before, never heard of."

Now his brewery participates in 50 to 60 festivals a year. He sees them as a valuable marketing tool. "No Web page or photo's going to do it justice," he said. "You need to smell the beer and taste the beer."

However, Surly's national sales manager, Corey Shovein, isn't sold on festivals' marketing effectiveness. "Maybe 15 years ago that was an important part of doing festivals, but now the marketing side of it has become less important," he said. "Unfortunately, beer festivals are sometimes too long and it's more about people getting drunk and no one remembers what the hell they had."

Shovein also laments that some for-profit festivals ask breweries to donate their beer, including the sought-after stuff his paying customers clamor for. "It's difficult to justify how a one-day festival should get a beer when I've got a guy who has two or three draft lines from us all the time — he should get an extra keg of that beer."

Beer list politics aside, Dave D'Amalfi of Forest Lake — who attended the small, 21-brewery Border Battle Beer Fest last weekend — hasn't met a beer fest he didn't enjoy.

"The worst thing that's ever happened was I lost my phone when I was too buzzed up," the 25-year-old said, chuckling. "Other than that I had a great time."