Casu martzu

Casu martzu (Sardinian: [ˈkazu ˈmaɾtsu]; lit. 'rotten cheese') is a Sardinian sheep milk cheese that contains live fly maggots.

The larvae of the cheese fly (Piophila casei) are deliberately introduced to pecorino cheese, where their digestive action produces an advanced level of fermentation, including a breakdown of the cheese's fats. The cheese's texture softens, and a liquid called làgrima ('teardrop') may seep out.

It is possible that the larvae could survive in the intestine, causing enteric pseudomyiasis, which can manifest as nausea, vomiting and gastrointestinal upset; however, no cases have been linked to the cheese. Additionally, these larvae can carry harmful microorganisms that may lead to infections. Due to these risks, Italian authorities have banned the sale of this cheese, deeming it dangerous. Consequently, it is also prohibited across the European Union, as EU food safety regulations mandate that only food safe for consumption can be sold.

Variations of this cheese also exist in Corsica, France, where it is called casgiu merzu; it is especially produced in some Southern Corsican villages such as Sartène.

Casu martzu is created by leaving whole pecorino cheeses outside with part of the rind removed to allow the cheese fly Piophila casei to lay eggs in the cheese. When the eggs hatch, the larvae begin to eat through the cheese. The acid from the maggots' digestive system breaks down the cheese's fats, making the texture of the cheese very soft. By the time it is ready for consumption, a typical casu martzu will contain thousands of maggots. Pecorino is most desirable if made from milk collected towards the end of June, due to the effects of the reproductive cycle of sheep on their lactation, and local fermentation traditions associate higher quality casu martzu with exposure to a warm sirocco wind, which is thought to additionally soften the cheese to encourage further maggot activity. The overall fermentation process takes a total of three months.

Casu martzu is considered by Sardinian aficionados to be unsafe to eat if the maggots in the cheese have died. Allowances are made for cheese that has been refrigerated, which also quickly kills the maggots. Some people prefer not to ingest the maggots^{[citation needed]}. They might place the cheese in a sealed paper bag, starving the maggots of oxygen. Modern preservation techniques have expanded the cheese's shelf life to several years, where it would previously be unobtainable outside of late summer and early autumn.

When the cheese has fermented enough, it is often cut into thin strips and spread on moistened Sardinian flatbread (pane carasau), to be served with a strong red wine such as cannonau. The flavor is described as "intense", with Mediterranean, pastoral, and spicy notes. The aftertaste is strong enough to remain for hours after a single serving. Because the larvae in the cheese can launch themselves distances up to 15 centimetres (6 in) when disturbed, diners hold their hands above the sandwich to prevent the maggots from leaping.

It is possible for the larvae to survive the stomach acid and remain in the intestine, leading to a condition called pseudomyiasis. There have been documented cases of pseudomyiasis with P. casei, although a report by CNN claims no such cases have been linked to casu marzu. The larvae may also carry harmful microorganisms that could cause infections.