A cluster of workers at Ventura County berry farms have been diagnosed with a rare disease often transmitted through sick animals’ urine, according to a public health advisory distributed to local doctors by county health officials Tuesday.

The bacterial infection, leptospirosis, has resulted in severe symptoms for some workers, including meningitis, an inflammation of the brain lining and spinal cord. Symptoms for mild cases included headaches and fevers.

The disease, which can be fatal, rarely spreads from human to human, according to the U.S. Centers for Disease Control and Prevention.

Ventura County Public Health has not given an official case count, but said it had not identified any known danger to the public. The county’s agriculture commissioner was aware of 18 cases, the Ventura County Star reported.

Patients experienced an onset of symptoms between September and November, coming from multiple parts of the county. Symptom onset typically occurs between two and 30 days after exposure, and symptoms can last for months if untreated, according to the CDC.

Officials are still working to identify a common exposure but have noted many patients worked with caneberry hoop houses — greenhouse structures to shelter the crops — and recommended healthcare providers consider a leptospirosis diagnosis for agricultural workers, particularly berry harvesters.

Rodents are a common source and transmitter of disease, though other mammals — including livestock, cats and dogs — can transmit it as well.

The disease is spread through bodily fluids, such as urine, and is often contracted through cuts and abrasions that contact contaminated water and soil, where the bacteria can survive for months. Humans can also contract the illness through contaminated food.

Symptoms often begin mild, with fevers, chills, vomiting and headaches. Some cases can then enter a second, more severe phase that can result in kidney or liver failure.

Ventura County Public Health recommends agriculture and berry harvesters regularly rinse any cuts with soap and water and cover them with bandages. They also recommend wearing waterproof clothing and protection while working outdoors, including gloves and long-sleeve shirts and pants.

While there is no evidence of spread to the larger community, according to the department, residents should wash hands frequently and work to control rodents around their property if possible.

Pet owners can consult a veterinarian about leptospirosis vaccinations and should keep pets away from ponds, lakes and other natural bodies of water.