I've recently been enjoying quite a lot of strong cheese. I'm hooked. I've been eying the available brands and types in an attempt to find one that really knocks my socks off. Today at work I learned of where this fascination could ultimately lead though, and the road to trying progressively more and more pungent cheeses seems to lead to a land upon which I don't really want to trod.
Derived from Pecorino Sardo, casu marzu goes beyond typical fermentation to a stage most would consider 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 of the cheese's fats. The texture of the cheese becomes very soft, with some liquid (called lagrima, from the Sardinian for "tears") seeping out. The larvae themselves appear as translucent white worms, about 8 mm (1/3 inch) long. When disturbed, the larvae can jump for distances up to 15 cm (6 inches). Some people clear the larvae from the cheese before consuming; others do not.
Yaroslav Trofimov, in the August 23, 2000 edition of The Wall Street Journal, describes the cheese as "a viscous, pungent goo that burns the tongue and can affect other parts of the body". Susan Herrmann Loomis reports an encounter (in a 2002 Bon Appétit article):
* 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, abdominal pain, and bloody diarrhea.
Because of these health threats, or simply because it is considered a contaminated product, casu marzu 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 any other type of pecorino's price.