Jun. 25, 2009 (United Press International) -- A giant biotechnology firm has begun an intensive cleanup of a Boston plant to kill a virus that could infect drugs that treat genetic disorders, the firm says.

Genzyme Corp., the world's third-largest biotechnology company, also received authorization to begin shipping drugs from finished lots that had been held in inventory after testing showed no evidence of viral contamination, the company told United Press International Thursday.

To kill the Vesivirus 2117 strain, which also showed up at the plant in November, Genzyme disassembled and removed equipment, scrubbed all surfaces with spore-killing bleach and dispersed clouds of vaporized hydrogen peroxide throughout the 185,000-square-foot production area of its Boston plant.

The U.S. Food and Drug Administration, which is investigating, has not determined the contamination's root cause.

The temporary production standstill comes when inventories for the halted drugs, Cerezyme and Fabrazyme, "are not sufficient to avoid shortages," Genzyme said.

Cerezyme treats Gaucher disease and Fabrazyme treats Fabry disease. Both conditions cause waste to build up in the body, swelling organs.

Because of the temporary production shutdown, doses of the intravenous drug to about 8,000 patients are being rationed.

Genzyme hopes to resume production "by the end of July," Mark Bamforth, senior vice president for corporate operations, told UPI.

The Cambridge, Mass., company met this week with the National Gaucher Foundation's medical advisory board to formulate clinical guidelines for use by U.S. and other physicians while Cerezyme supplies are limited, Genzyme said.

It also plans meetings to create guidelines for managing Fabrazyme supplies, it said.