Disease-ridden rams may have been used as the first bio-weapon, dating back to the 14th century BC, according to a new review. The historical documents hint that the Hittites, whose empire stretched from modern-day Turkey to northern Syria, was the first to use biological warfare.

Italian researcher Siro Trevisanato says the Hittites "were the first people to wage bioterrorism," using diseased sheep, to weaken the enemies with tularemia, a devastating bacterial infection that remains a potential bioterror threat even today.

Tularemia, also known as rabbit fever, can pass from animals such as rabbits and sheep to humans through various routes, most commonly through insects such as ticks that hop between species. The bacterium responsible for tularemia, Francisella tularensis, causes symptoms ranging from skin ulcers to respiratory failure.

Modern medication can stop the tularemia from becoming deadly. But without proper antibiotic treatment, about 15 percent of infected individuals die, says Trevisanato, a former microbiologist who has delved into the ancient texts.

He believes tularemia is to blame for a deadly epidemic dubbed the "Hittite plague" which raged through the Middle East in the 14th century BC. An example was demonstrated in 1325 B.C. when the Hittites sacked the Phoenician city of Symra on what is now the border of Lebanon and Syria.

A decade later, the Hittites to the north attacked the weakened area around Simyra. "The Hittites were able to steal booty, including animals, and brought the animals home," along with the tularemia the livestock harboured, Trevisanato explains. Not too long after, the Hittites themselves apparently began to suffer from an epidemic of tularemia.