Hawai‘i’s Killer: Leptospirosis
After a century, we still underestimate leptospirosis. And what we don’t know can kill us.
Damien Marks had just finished his junior year at Damien High School when he swam with his football teammates at Kapena Falls in Nu‘uanu. The next day, he became ill with a high fever. Because his parents resided in Kalaupapa, he lived on Oahu with his older sister, who took him to a clinic in Wai‘anae three days in a row. Diagnosed with the flu, he was sent home each time. On the fourth day, the 17-year-old was admitted to Queen’s Hospital. Soon after, he died. The cause: leptospirosis.
The year was 1985, but the memory is as painful and frustrating as ever to Damien’s father, Richard Marks. After doctors at Queen’s notified him of the severity of the illness, he was unable to catch a plane out of Kalaupapa before his son died. Damien, who stood six feet tall and weighed 200 pounds, apparently had a cut on his hand, making him more susceptible to the disease than his teammates-none of whom became ill.
Richard Marks said he never received a satisfactory explanation from anyone about his son, the last child born to Hansen’s Disease patients on Moloka‘i. To this day, he wonders if posted signs, which were nowhere to be found, might have saved Damien’s life by prompting the young man or his friends to mention the possibility of leptospirosis to physicians.
A century after it was first identified in Hawai‘i, leptospirosis continues to be a quiet, underestimated threat. Its ravages astonish its victims and their families. It is caused by a microscopic spirochete-corkscrew-shaped bacteria-called Leptospira interrogans. People become infected by swimming or wading in freshwater puddles, ponds, streams or mud contaminated with the urine, blood or tissues of infected animals, most commonly rats, mongooses, swine and cows. Open cuts or abrasions are welcome portals, but any orifice with soft tissue-mouth, nose and eyes-will invite pathogens.
High rainfall makes leptospirosis relatively common in Hawai‘i. Some years, the Islands report more cases than the rest of the country combined, says Bruce Anderson, former director of the state Department of Health and currently the Environmental Health program director at the John A. Burns School of Medicine. Just how common, nobody really knows. Based on his research, Anderson estimates that less than 10 percent of cases are actually reported.
Why aren’t more cases reported? As Anderson points out, “Leptospirosis is called the great imitator, because it imitates so many other diseases.” Sometimes, several weeks pass before symptoms arise, and those symptoms-fever, headache, chills, sweating, muscle pain, red eyes and vomiting-look exactly like a common cold or the flu. Solving the mystery is critical, because patients who aren’t treated with antibiotics early enough could suffer from kidney failure, blood or nervous system damage. Or they could die.
Two decades after Damien Marks’s death, the danger persists. In January, Simon Hultman visited his family on the Big Island and swam in Waipi‘o Valley-known for its high rate of infections. When the 22-year-old returned to college in Maryland, he went to the emergency room complaining of a fever. Five days later, he died. Test results revealed leptospirosis. Most alarming is that he was treated with antibiotics. “I think it’s possible to have a serious outcome from leptospirosis even when you’re treated appropriately,” says Dr. Paul Effler, state epidemiologist at Hawai‘i’s Department of Health. “When people talk about leptospirosis, that’s what we all fear.” But the wrong medicine or a delay in treatment can be life-threatening.
Visitors are frequently at risk. They get exposed while hiking or swimming in Hawai‘i, but they don’t become ill until they return home. On the Mainland, physicians are less aware of the disease and more inclined toward conservative treatment. Unfortunately, “early in the illness is where the battle is won or lost,” says Effler. While the solution may seem simple-immediate antibiotics-doctors are constantly discouraged from prescribing antibiotics unless absolutely necessary because of disease-resistance issues. And only certain ones will work.
An estimated 15 different strains of leptospirosis exist in Hawai‘i. Exposure to one strain might create an immunity, but leave a person vulnerable to others. From 1977 through 1996, seven Hawai‘i residents suffered multiple infections, presumably from different strains. Five were exposed while working.
Most in peril are people whose jobs keep them in fresh water or mud. Taro and prawn farmers have been particularly susceptible. The first case diagnosed in Hawai‘i occurred among sugarcane workers in 1907, says David Sasaski, state public health veterinarian, who has studied leptospirosis for more than 20 years.
However, Sasaki points out that with more people swimming in streams, exposure during recreation increased dramatically through the 1980s. Adventure travelers are the new high-risk group.
There are leptospirosis hot spots. Between 1993 and 2002, 178 people contracted the disease on the Big Island, with a cluster of infections originating in Waipio Valley and nearby communities. Kauai reported 131 cases. The majority occurred on the North Shore (Kilauea-Hanalei) and in the Waimea River.
The Big Island has the largest number of cases, Kauai the highest incidence rate, according to the Department of Health’s latest Communicable Disease Report. Enigmatically, Maui has had relatively few cases. Only nine were described over the same 10-year period, with two from Molokai. Sources included the Seven Pools area, Huelo and Iao Valley.
Maunawili Falls produces the most cases on Oahu. Something new? No, just easy trail access attracting more people to the area. Many have become seriously ill, indicating a virulent strain of the organism there. Kapena Falls, another popular swimming hole, has also produced a number of cases.
At the Hawai‘i Nature Center, 18,000 school children on O‘ahu each year come to research living organisms in the mountain streams-often right next to leptospirosis warning signs. Gregory Dunn, the center’s executive director, sees this as an educational opportunity for an “age-appropriate introduction to leptospirosis and other waterborne diseases” Instructors talk about leptospirosis and check all hands for wounds. “If they have an open cut or sore, we don’t let them touch the water.”
After the lesson, the children are led to a sink to wash their hands. “We’re very careful in that respect,” says Dunn. His message to families: “People should not be afraid to enjoy our wild areas, but should use common sense.”
Why not just evaluate every stream and post signs? Unfortunately, there is no test to determine if water is contaminated. Most health officials believe that leptospirosis is present everywhere there is fresh water in the Islands. Debate rages about warning signs. Do they alarm or inform? Are they harmful to our visitor industry? Should officials put them everywhere? How can the state afford to replace signs that constantly disappear to become dorm-room decor?
The good news is that the pathogens are weak and cannot thrive in salt water. These organisms can survive for months in the mud, but acid, heat, drying or freezing kills them.
An average of 500 to 600 people get tested every year in Hawai‘i. Of those diagnosed, approximately 60 percent end up hospitalized. That’s usually because the cases getting reported are the critical ones, accompanied by jaundice and kidney failure. The Centers for Disease Control estimates that there are 100 to 200 cases annually throughout the United States, with about half occurring in Hawai‘i. Still, because physicians here are more aware of the disease, our survival rate is better.
Early diagnosis is essential, yet available tests are still inadequate. Labor-intensive and expensive, they require that blood samples be mailed to the Centers for Disease Control in Atlanta. A screening test that provides preliminary results is available in Hawai‘i, and Sasaki says the state lab is trying to develop a microscopic agglutination test that would provide more information sooner. However, resources are limited.
Part of the challenge of clinical recognition, notes Sasaki, is that to diagnose leptospirosis definitively, two blood samples from each patient must be sent to the CDC: one when he is ill, and a follow-up weeks later when he is well, to determine if the number of antibodies has risen. The problem is that when the illness is mild, it resembles a cold or the flu, so leptospirosis isn’t suspected and the first test isn’t administered. Even when it is, an analysis of the first blood sample is not authoritative (nor will the CDC waste its time analyzing only one). However, few people return for follow-up tests once they become well. In addition, leptospirosis is not the CDC’s biggest concern. SARS, dengue and bird flu usually take priority, meaning a potential delay of weeks or months for results.
The disease’s most common source is that scourge of mankind: the rat. An estimated 30 percent to 40 percent of all three species of rats in Hawai‘i are infected. They carry and shed these bacteria throughout their lives. An infamous attempt to control the swelling nocturnal rat population-by importing the diurnal mongoose-doubled the problem. Now both animals contaminate fresh water.
Leptospirosis also threatens pets. Cats can help protect us against the disease by minimizing rodent populations, but they have been found to carry low levels of antibodies, suggesting exposure. Sasaki admits that “there’s still a lot that’s not known” about infection in domestic animals. Dogs, for instance, could display no symptoms at all, or have fever, vomiting, abdominal pain, diarrhea, weakness, stiffness, muscle pain or lack of appetite. Younger animals tend to be more seriously affected than older animals. The incubation period can be as long as 30 days or more. Though not foolproof, a vaccine is available for farm animals and pets.
Is there a way to control leptospirosis? “For any disease for which there’s [a wild] animal reservoir, it’s going to be really hard,” says Effler. Resources would disappear down the drain, and the futile attempt would adversely affect the environment. Essentially, “there’s really no way to eradicate it.” The best control is prevention, avoiding exposure. Early diagnosis and prompt treatment are the next vital steps.
Hawai‘i probably will never witness a dramatic outbreak of leptospirosis, but it “is a long-term problem that is going to be with us,” says Anderson. “It’s a significant health risk that is largely unrecognized and has been under reported. It’s a more insidious problem that continues to be a concern. It does pose a risk to both residents and visitors.”
We may have to tolerate leptospirosis as an endemic disease, but we should never underestimate something so mysterious and deadly.