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Leptospirosis is a rare, contagious but treatable disease that affects humans and animals.

"Three of the 10 cases this year required admission into the special care unit," said Lt. Cmdr. Reid Holtzclaw, an internal medicine doctor at the hospital. "And those are only the cases that have come to our attention."

Many of the reported cases of Leptospirosis have involved Marines training in the Northern Training Area and hiking or swimming near falls and fresh water.

Leptospirosis can be found worldwide, but it is more prevalent in sub-tropical climates such as Okinawa's. The bacteria are usually passed from animals to humans by way of fresh water sources contaminated by animal urine.

Small mammals, such as mice, rats, mongoose and other rodents are the common repositories of the bacteria, according to Holtzclaw, but some bigger animals such as cattle and dogs can be carriers as well.

It causes a wide range of symptoms in humans, but in some cases, infected persons may have no symptoms whatsoever.

Flu-like symptoms, severe abdominal pains, coughing up blood and kidney failure are some of the symptoms doctors have observed in cases this year, according to Holtzclaw.

Although most varieties of Leptospirosis are easily treated, some cases of the disease can be fatal if left untreated.

Leptospirosis is treated with antibiotics, such as doxycycline or penicillin, which should be given early in the course of the disease, according to the Centers for Disease Control and Prevention. Intravenous antibiotics may be required for persons with more severe symptoms.

Hospital officials are urging people on Okinawa to avoid high risk areas to reduce the possibility of contracting the bacteria. "Marines in the Northern Training Area are given an oral-antibiotic to take once a week that works if taken properly," Holtzclaw said. "Others should try to minimize or stay away from fresh water sources because we don't want to see anyone else in our special care unit."

Hospital officials offered several other tips to minimize the chances of contracting the bacteria: wear protective gear before entering potentially contaminated fresh water areas, use a chemical treatment or boil fresh water before drinking, and vaccinate pets to help avoid contracting it from them.

Persons with symptoms suggestive of Leptospirosis should contact a health care provider immediately.