Casu Marzu: World's Most Dangerous Cheese?

By: Diane Bobis - Updated: 19 Apr 2018 | *Discuss Tweet

Casu Marzu is not your average cheese lover’s cheese. The name of this Sardinian speciality literally translates to “rotten cheese.” And if that’s not enough to scare you away, how about a few thousand wriggling maggots?

That’s right. Casu Marzu, otherwise known as walking cheese, is an Italian sheep’s milk variety with a little something extra. You could say it’s alive. Very alive.

How Casu Marzu is Made

Casu Marzu begins as Pecorino Sardo (Fiore Sardo), a cheese that’s typically soaked in brine, smoked, and left to ripen in the cheese cellars of central Sardinia. But to produce Casu Marzu, cheese makers set the Pecorino Sardo outside in the open – uncovered – and allow cheese flies (scientifically named Piophila casei) to lay eggs inside of it.

As the eggs hatch into a myriad of white transparent maggots, they feed on the cheese. By doing so, they produce enzymes that promote fermentation and cause fats within the Casu Marzu to decompose.

Sometimes, cuts are made into the rind of Pecorino Sardo and already-hatched maggots are introduced into the cheese. This speeds the whole cheese making process along.

How Casu Marzu Tastes

Casu Marzu is a local delicacy in very high demand. It’s a highly pungent, super soft cheese that oozes tears (“lagrima”), and fittingly so, as it tends to burn on the tongue.

Some say Casu Marzu tastes like an extremely ripe Gorgonzola. That is, of course, without the savoury blue veins and with a whole lot of larva. One piece of Casu Marzu may be populated by thousands of living, breathing maggots.

In fact, local Sardinians will tell you the spicy, creamy cheese is only okay to eat if the maggots are still moving. Apparently, once the maggots are dead, the Casu Marzu has gone bad – decayed to a point that’s too toxic for human consumption.

Is Casu Marzu Dangerous?

Casu Marzu has been declared illegal and not in compliance with EU hygienic standards. It is banned by Italian health laws and not sold in shops. In addition to numerous anecdotal reports of allergic reaction (including burning, crawling skin sensations that last for days), there is increasing concern of risk for enteric myiasis, or intestinal larval infection.

Once ingested, it’s possible for the Piophila casei larvae to pass through the human stomach without dying (sometimes stomach acids aren’t enough to kill them). In that case, the maggots may take up residency in the intestines for some time. They can cause serious lesions and bore through intestinal walls, resulting in abdominal pain, nausea, vomiting, and bloody diarrhoea.

Despite the health warnings, people in Sardinia say they’ve been eating Casu Marzu for hundreds of years without any problem. In fact, the Italian cheese is often brought out for special occasions like birthdays, bachelor parties, and weddings. According to folklore, Casu Marzu is even an aphrodisiac.

Casu Marzu Buying & Serving Tips

Casu Marzu cannot be legally sold in Italy, but mountain shepherds continue to produce it in small quantities for the black market. It’s often kept under the table, but only for the most trusted customers. Selling or serving it is punishable by a hefty fine.

If you find yourself with strong stomach and a local Sardinian connection, Casu Marzu may be procured – for about twice the price per pound as regular Pecorino. It’s generally served with thin slices of Sardinian bread (pane carasau) and a strong, red wine called Cannonau.

One final note of caution, some people wear eye protection when eating Casu Marzu: the maggots are known to jump as high as six inches and straight toward the eyeballs with exact precision. At a minimum, make a maggot sandwich and shield your eyes with your hand as you take a bite.

Buono appetito!

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Share Your Story, Join the Discussion or Seek Advice.. [Add a Comment]

Lee - 19-Apr-18 @ 1:42 AM My Yorkshire grandfather(I'm 77,do math)used to discuss with my father how they enjoyed ' jumper '(maggots) cheese so it appears to be universal... 'waste not ,want not'?

Jimbt - 4-Jun-17 @ 9:37 PM Good reason that they slice thinly - that should reduce the risk of infection ??

ronnie - 11-Mar-17 @ 1:57 PM First time i read thisi actually thought that before you eat it,maybe,some how you get the maggots out of the way but not when i read it again to find that you actually eat the cheese with those wriggly stuffs all around oh geez yuck, only the sight of it is enough to send anyone throwing up for a whole week.

itsbybitsy - 24-Oct-14 @ 10:40 AM @williamwhitehead...interesting idea, I'd rather just avoid it personally :)

William Whitehead - 22-Oct-14 @ 2:45 AM You could always put the cheese in a Ziploc to suffocate the maggots before eating.

vivian - 23-Nov-13 @ 4:01 AM I would try Casu Marzu, if it weren't for the chance of a parasitic larvae infection. The risk of getting this infection outweighs the benefit of trying something new, I suppose. I've had an intestinal parasitic infection before, and it was NOT fun. Was in a lot of pain for a whole year before I managed to get a correct diagnosis. Other than that, though, I am generally a very adventurous eater. I guess I'd try this cheese if I could somehow pick out all the larvae before eating it.

Santi - 5-Jun-12 @ 4:59 AM Yum...the best part of this cheese is the jumping maggots. That's where the flavors at!

galera - 30-May-12 @ 10:25 PM I was born in Corsica, a french island close to Sardinia and we have "Casgiu merzu" as well, rotten cheese also. It's not made the same way. and it's not done on purpose.From time to time, specific flies choose a cheese and the process of rotting begins. It doesn't taste quite the same as the one described but is excellent, and I have it since I am five, as the rest of my family.It is really powerful and looked after If you close your eyes, you are unable to say it is alive once in mouth.

Sardus - 18-May-12 @ 2:05 AM I know that my english is not perfect, I'm sorry.

Sardus - 18-May-12 @ 2:03 AM Hi! I'm from Sardinia and obviously I like casu marzu so much! Don't worry, I can understand that most of people find it very disgusting and impossible to eat, so when I offer it to some friend, it's ok if he doesn't want to taste it :) I will tell you an exemple: in a group of 20 men 15 of them are not so brave to taste it and only 5 of them want to try...these 5 men find it very strong and strange...but they will appreciate it! So: the bad thing is only the first time (because of the strange and uncommon dish)! This cheese was probably born because of poorty: some stocks of cheese was infested by that fly and the poor shepard had only that cheese to eat..he found it tasty and safe...it was ok(that's my opinion)! If you look around in the food world you can find some others exemple similar to this one: in the past men were used to drink grape juice...but some liters were probably stocked for long time...and voilà! the first wine was born! Come to Sardegna to visit us and remember that our island is politically part of Italy, but her story, language and culture is so different from Italy! You will notice it :)

Harji - 9-May-12 @ 3:16 PM | Intestinal larval infection Oh god, no.

kate - 5-May-12 @ 6:09 PM That is the most discusting thing I have ever read I find it almost imposible to belive anyone could eat such stuff even the very thought of it makes me sick.