Niabi Zoo's youngest giraffe, Jabu, died last month as a result of an inflamed heart, necropsy results show.

The giraffe died Oct. 7, and its body was taken to the University of Illinois for testing. Pathologists could not, however, determine why the 3-year-old male reticulated giraffe had heart trouble.

"The necropsy included a gross and microscopic examination of the internal organs, cultures for bacteria and virus, and PCR tests for specific pathogens," Zoo Director Tom Stalf said. "They have concluded the cause of death was an acute myocarditis, or inflammation of the heart.

"A specific cause of the infection was not identified."

Stalf said tests for West Nile virus also were negative.

Jabu had been at the Coal Valley, Ill., zoo for about two years. At the time of his death, he was under a veterinarian's care, because he had been "lethargic," Stalf said. He was the youngest of Niabi's four giraffes.

The other giraffes showed no sign of illness at the time of Jabu's death, but zoo staff wanted to be certain they were not in danger, which is why the extensive testing was performed.