Pern periodically experiences Threadfalls, in which this deadly organism rains down from the sky.

Two shells containing the deadly organism were mixed in with the shipment sent by the arms supplier.

Cultures of deadly organisms have for many years been circulating overseas.

The effective direct mortality rate was forty-three percent-not at all perfect, but still the deadliest viral organism in recorded human history.

The recorded Losira explains that while creating the planet they created a deadly organism.

In creating this planet, we have accidentally created a deadly organism.

Yet they hadn't been able to fight this deadly organism.

"Then how about giving us a way to get rid of this deadly organism?"

So he asked, "What do you know about the deadly organism that's on board this station?"

"Our scientists have been unable to find a way to eliminate the deadly organism from our bodies."