Infected rams and donkeys were the earliest bioweapons, according to a new study which dates the use of biological warfare back more than 3,300 years. According to a review published in the Journal of Medical Hypotheses, two ancient populations, the Arzawans and the Hittites, engaged "in mutual use of contaminated animals" during the 1320-1318 B.C. Anatolian war. "The animals were carriers of Francisella tularensis, the causative agent of tularemia," author Siro Trevisanato, a molecular biologist based in Oakville, Ontario, Canada told Discovery News. Also known as "rabbit fever," tularemia is a devastating disease which even today can be fatal, if not treated with antibiotics. Its symptoms range from skin ulcers, swollen and painful lymph glands to pneumonia, fever, chills, progressive weakness and respiratory failure.