Symptoms included fever and chills, head and muscle aches, nausea and vomiting, jaundice, abdominal pain, diarrhea and rashes. Some cases were mild; others required hospitalization.
Dierks, the III Marine Expeditionary Force’s preventative medicine officer, and her team from U.S. Naval Hospital Okinawa were tasked with the scientific who-done-it of figuring out the cause and stopping more from falling ill.
Since the initial deluge, the number of ailing 3rd Division Marines crept up to at least 65 and could reach upwards of 75, Marine officials and Dierks said this week. But they all have left the hospital in full recovery, and health officials think they may have finally turned the tide by identifying and isolating the cause, though some questions remain.
“What we’re trying to do is to get the full picture of the outbreak,” Dierks said Tuesday from an exercise in the Philippines. Such an outbreak “has huge implications for the force in general.”
The first major hurdle in curbing an outbreak is identifying that there is one, Dierks said. She said the Navy physicians on Okinawa picked up on the mystery illness quickly and sounded an alert.
They learned that the Marines had all recently trained at the Jungle Warfare Training Center at Camp Gonsalves in northern Okinawa. It features pools, pits and culverts that Marines must claw and scrape their way through, sometimes submerging themselves. It is the only one like it in the Defense Department; 3,000 troops pass through annually, Marine officials said.
Leptospirosis — a bacterial disease that comes in different variants affecting humans as well as animals — was the suspected culprit from the start.
The bacteria is often found in stagnant pools and is prevalent in Hawaii, Philippines and other tropical locales, Dierks said. It is hard to diagnose, however, as some people develop no symptoms while others are pushed to the brink of death.
Marines on Okinawa have seen leptospirosis before. A similar outbreak hit the training facility in 1987, and a standing Marine order recommends personnel stay out of fresh water north of Camp Hansen due to bacteria.
“This is not a completely new phenomenon,” Dierks said. “We do expect this, but we don’t expect people to get sick. That is why we’re relooking at things.”
Because of the risks, Marines training at the center undergo a weekly regiment of Doxycycline, which is used to treat bacterial infections, during and after the training.
“This is the only place where you’d see this type of exposure,” she said.
Within a week of the initial warning, Dierks and experts were taking samples of the water in the pools and pits. They came back negative, further deepening the mystery.
Training at the center continued, but water submersion was prohibited. Marines have also been instructed to wash down thoroughly after training and dry their uniforms.
The team then turned to the local wildlife population for answers.
Rain had increased recently, which could mean an increase in the mongoose population, Dierks said. Mongooses are known carriers of leptospirosis, which concentrates in their urine. If they urinated in or near the water, they could be to blame.
Teams tried unsuccessfully to catch a mongoose. They then turned their attention to boars and mice, which could also hold the key.
At the same time, they learned that the previous group to go through the training may have also been treated for the mystery illness. They called all of the Marines in and took blood tests, which are pending. The results will provide the true scope of the issue.
They have also coordinated with the Army and Air Force handlers of the military working dogs, because they too can be affected. The dogs are given a vaccine, but it is for stateside variants of the bacteria.
Dierks believes they will have definitive answers by the end of November. By January, they expect an action plan so they can start to fight back.
While being sick is certainly not fun, Dierks said this could be a unique opportunity to test the 30-year-old medication regimen that Marines undertake at the facility and possibly make improvements that have real world implications to those in the field.
“Medical science is a learning science,” Dierks said. “We don’t want this to happen again.”