Dangerous bacteria lurks in inland waters
By Jan TenBruggencate
Advertiser Science Writer
A potentially severe bacterial disease is lurking in Hawai'i's streams and mountain pools, fishponds and mudholes.
Cory Lum • The Honolulu Advertiser
In the heat of summer, when tourists and residents are prone to wade or swim in cool upland ponds, leptospirosis will affect some of them, with symptoms similar to the flu: headache, fever or chills, muscle ache and nausea. A few will become seriously ill, and death is possible from swelling of the liver or kidneys, heart failure or other complications.
Tony Tauasosi, 15, cools off at Manoa Falls despite nearby leptospirosis warning signs.
"Hawai'i has the highest rates of leptospirosis in the country, by a long shot," said Dr. Bruce Anderson, head of the state Department of Health.
Although many sufferers escape with mild flulike symptoms and never learn they had the disease, for some it can be so serious as to require hospitalization.
During the 1990s, 43.5 cases of the disease were confirmed annually in Hawai'i. Seven people died from leptospirosis during that time, with the most recent death in 1998.
Anderson became concerned in the 1970s, when two young, healthy aquaculture workers became ill and died of the disease. Subsequent studies found that a high percentage of such workers had been exposed to the disease.
"In high-risk industries, the infection rate can be as high as 60 percent," Anderson said. "It is a significant problem. I would rank it as one of the most serious infectious disease problems in the state."
But many people have never heard of it.
The disease was first diagnosed among sugar workers in Hawai'i a century ago. More recently, taro farmers and aquaculture workers have been identified as being at particular risk, but anyone who is exposed to open freshwater areas in the state can be infected.
The bacteria get into the water from feral animals.
"In Hawai'i, wild animals such as rats, mice and mongooses are the primary reservoirs of infection, harboring organisms in their kidneys and shedding them in their urine. Domestic animals, particularly dogs and farm animals such as cattle and swine, are also important reservoirs of infection in residential and agricultural environments," write researchers Charles R. Middleton, Dr. Vernon Ansdell and Dr. David Sasaki, who is the state public health veterinarian, in the July issue of the Hawai'i Medical Journal.
One of the problems is that in the early stages, when it is most easily treated, leptospirosis can produce symptoms similar to other diseases.
"Leptospirosis is called a great imitator," Anderson said. "It mimics a lot of other diseases, like the flu. It is usually diagnosed when someone is so ill they end up going to the hospital."
There is no good estimate of how many people get the disease in Hawai'i each year, because mild cases are misdiagnosed or not reported to health authorities at all. The Hawai'i Medical Journal article says more than 600 people in Hawai'i are tested for leptospirosis each year, but that is a fraction of the actual occurrences because the disease "is usually recognized only when it is suspected."
Kaua'i has the highest rate of infection in the Islands, but the disease is reported on O'ahu, Moloka'i, Lana'i, Maui and Hawai'i as well. Extensive testing has found the infectious organism in wild pigs, rats, mongooses and other animals in the Islands.
State communicable disease chief Dr. Phil Bruno said that while someone who gets the disease becomes immune to that strain, there are many different strains of leptospirosis, and some people have suffered repeated infections.
Leptospirosis can enter the body through cuts, and anyone with open wounds should stay out of the water and away from mud, experts say. It can also enter through the body's mucous membranes, so people should avoid dunking their heads and exposing eyes, nose and mouth.
"If you're going in, you should wear a face mask," Sasaki said.
There is also evidence that long-term exposure to water can soften the skin and allow the disease to enter directly through healthy skin. This may be one of the means of exposure for agricultural workers who are in long-term contact with water or mud.
A state Health Department brochure lists five recommendations for avoiding getting the disease:
• Don't swim or wade with an open wound, and don't dunk your head in the water.
• Wear protective clothing, including boots, gloves, long-sleeved shirts and heavy pants when working in possibly contaminated areas.
• Never drink stream water without boiling or chemical treatment, and protect catchment water from animal contamination.
• Control rodents and mongooses around home or work sites.
• While there is no vaccination for humans, pets can be vaccinated to protect them from the disease.
Leptospirosis has an incubation period of as long as three weeks. North Kaua'i physician Dr. Jeffrey Goodman, who Bruno said may have more experience with the disease than any other doctor in the country, says symptoms can appear as early as two days after exposure, with an average of 10 days.
Sasaki said anyone who suffers flulike symptoms within three weeks of exposure to possibly contaminated water or mud should see a physician, and should be sure to inform the doctor of the exposure.
Antibiotics used to treat the disease work much better in early stages when the bacteria are circulating in the blood, Sasaki said. Treatment is more difficult later, when the bacteria are sequestered in the organs.
