Israel's Health Ministry is investigating several cases of leptospirosis, or field fever.
It is believed that the disease was contracted via a water source in the Golan Heights.
The Nature and Parks Authority closed the entrances to the Zavitan and Hazaaki streams after coli was found in the water. An additional sample will be taken.
"This is a seasonal trend which repeats itself every year when the water level is low. The source is probably cow feces, and the low water level allows for reproduction," the Nature and Parks Authority said.
"Regardless, act according to the signs posted on the Golan Heights trails," the Health Ministry said. "It is advisable not to enter standing water."
Leptospirosis can be found around the globe, but is more common in tropical areas. The bacteria harms a wide variety of animals, and is usually transmitted via rats, though it can pass to people as well. Symptoms include headaches, muscle aches, and fever, but can also include pulmonary hemorrhage, kidney failure, and meningitis.