The U.S. National Institutes of Health says it has uncovered more improperly stored pathogens, including the deadly toxin ricin and bacteria that cause plague, while searching its laboratories for hazardous materials.

The NIH opened an intensive probe of its facilities in July, after a researcher found vials of smallpox and other highly contagious viruses and bacteria in a laboratory storeroom in suburban Washington, D.C.  

Friday, the NIH said it found small amounts of five pathogens improperly stored at other facilities, and said those agents are required to be registered and stored at special high-security laboratories. The discoveries included sealed samples of pathogens that cause botulism and a rare tropical infection called melioidosis.

In a memorandum to employees, the agency said all of the toxins - including ricin found in a box with microbes dating from 1914 - have since been destroyed and that no employees had been endangered.

Separately Friday, the Food and Drug Administration said it had found vials of another improperly stored pathogen that causes food poisoning.  The FDA said the vials were found locked in a freezer and have since been properly secured.