Ancient written texts from the Middle East may reveal that the use of biological weapons dates back more than 3300 years, according to a new review.
The historical documents hint that the Hittites -- whose empire stretched from modern-day Turkey to northern Syria -- sent diseased rams to their enemies to weaken them with tularemia, a devastating bacterial infection that remains a potential bioterror threat even today, says the review.
Experts caution that more evidence is needed to firmly establish that the Hittites intended to spread disease using the animals. But they add that if this proves true, it might represent the earliest known use of biological warfare.
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 fatal. But without proper antibiotic treatment, about 15 percent of infected individuals die, says Siro Trevisanato, a former microbiologist who has delved into the ancient texts.
Tularemia is rare in many countries today, but remains a problem in some countries including Bulgaria, says Trevisanato, now based in Oakville, Ontario, Canada.
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. Around 1335 BC, letters to the Egyptian king Akhenaten reported a pestilence in Simyra, a Phoenician city near what is now the border between Lebanon and Syria.
The texts describe a terrible illness causing disabilities and death. Most tellingly, they mention that, because of the plague, donkeys were banned from being used in caravans.
According to Trevisanato, this indicates that the people living in the city were hit by tularemia. The disease can infect donkeys and the insects that they carry, so preventing the use of donkeys for transport may have been an attempt to quell its spread.
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.
History seems to have repeated itself a few years afterwards when another ancient people, the Arzawans from western Anatolia, saw the weakened Hittites to their east and decided to strike. "They thought, if we attack now, we can push the border back to where we want," Trevisanato says.
But strangely, during this period of warfare between 1320 and 1318 BC, records indicate that rams mysteriously began appearing on roads in Arzawans.
The Arzawans took the sheep to their villages and used them for livestock breeding. Soon after, though, they began to suspect a link between the appearance of the animals and the terrible disease ravaging their communities.
"They started wondering 'Why do these rams start showing up on the road?'" says Trevisanato. He believes that among the Hittites, "somebody must have had the bright idea" to send diseased rams over to their Arzawan enemies.
Ultimately, the Arzawans were so weakened that their attempt to conquer the Hittites failed.