Casu marzu

Casu marzu (also called casu modde or formaggio marcio) is a cheese found in Sardinia, Italy, notable for being riddled with live insect larvae. Casu marzu is Sardinian for "rotten cheese."

Derived from pecorino, casu marzu goes beyond typical fermentation to a stage most would consider to be decomposition, brought about by the digestive action of the larvae of the cheese fly, Piophila casei. These larvae are deliberately introduced to the cheese, promoting an advanced level of fermentation and breaking down the cheese's fats. The texture of the cheese becomes very soft, with some liquid (called "lagrima") seeping out. The larvae themselves appear as transparent, white worms, about 8 mm (1/3 inch) long. When disturbed, the larvae can jump for distances up to 15 cm (6 inches), prompting recommendations of eye protection for those eating the cheese. Some people clear the larvae from the cheese before consuming; others do not.

Yaroslav Trofimov, writing in The Wall Street Journal in 2000, describes the cheese as "a viscous, pungent goo that burns the tongue and can affect other parts of the body." It is typically enjoyed with Sardinian bread (pane carasau) and Cannonau, a strong red wine.

Several food safety issues have been raised with casu marzu:

• Anecdotal reports of allergic reactions.
• A risk of the decomposition advancing to a toxic state. (Folk wisdom in Sardinia holds that still-living larvae are an assurance that this has not yet happened.)
• Risk of enteric myiasis: intestinal larval infection. Piophila casei larvae can pass through the stomach alive (human stomach acids do not usually kill them) and take up residency for some period of time in the intestines, where they can cause serious lesions as they attempt to bore through the intestinal walls. Symptoms include nausea, vomiting, pain in the abdomen, and bloody diarrhea.

Because of these health threats, or simply because it is considered a contaminated product, casu marzu cheese cannot be legally sold in Italy. Within Sardinia, enforcement of the ban is sporadic and the cheese is available as a black market item, selling for about three times pecorino's price.

References

• Excerpts from Yaroslav Trofimov's Wall Street Journal article on casu marzu
• "Extreme Cuisine" page with a brief mention
• Bon Appetit article with a brief mention
• Lieutenant Brian F. Prendergast, USN (2001). Filth Flies: Significance, Surveillance and Control in Contingency Operations (.pdf format). Retrieved October 1, 2005.