For a small Midwestern city with a clean, wholesome reputation, Springfield's 1998 outbreak of leptospirosis seems nothing short of bizarre. It was by far the largest epidemic of that illness in United States history. Five years later no one knows what caused such an unusual disease to visit here on such a large scale.
What's certain is that people got sick from swimming in Lake Springfield. After the Ironhorse Triathlon, at least 98 hale and hardy competitors succumbed to fever and chills, headaches, muscle pains, or diarrhea. Another 248 recreational users of the lake came down with the same symptoms. Only 66 of the people in both groups tested positive for leptospirosis, but Donald Graham, head of infectious diseases at Springfield Clinic, says testing isn't sensitive enough to detect every case--he believes all 346 had the exotic disease.
In a normal year, Illinois sees only one or two instances of leptospirosis, and the entire United States logs fewer than 100 cases. That's because the bacteria is a creature of the tropics: leptospira prefers the perennially warm waters of places like Southeast Asia, Central America, and Hawaii, where most U.S. cases arise. Illinois can get mighty hot in the summer, but its frigid winters are normally sufficient to ward off the bug year-round.
The state's largest outbreak prior to Springfield's happened in 1991, when six boys went swimming in a small farm pond upstate. Leptospira bacteria is excreted in the urine of animals, most of whom show no sign of sickness but are only carriers of the thin spiral parasite. Though the illness is often mistaken for the flu and is rarely fatal, leptospirosis can stick around in someone for months. If not treated, it may progress to kidney or liver disease.
Though the mystery remains over what brought that bacteria to Lake Springfield, the incident has receded from public consciousness. Today the community seems content to assume that leptospira has sworn off the lake for good. Its shores are still the most desirable residential property in the city, as indicated by two recent proposals to build luxury condominiums there priced between $300,000 and $500,000.
Yet trouble may still lurk in the murky waters of Lake Springfield. Every summer since '98, bacteria in general has risen to unsafe and at times alarming levels. There is no quick test for leptospira, but measurements for a harmless variety of E. coli are taken twice a month to indicate when bacteria of all kinds are on the rise. The Illinois Department of Public Health recommends closing beaches when these readings rise above 235. But according to numbers posted on a Web site kept by City Water, Light and Power, which oversees Lake Springfield, that standard has been surpassed regularly after heavy rains, which wash bacteria into the lake from surrounding land. And last May and again in June, the numbers spiked up as high as 2,419 from a baseline in the single and double digits. In June 2001, readings in one end of the lake soared to 6,010. CWLP has closed the public beach for several days due to such high measurements, but it hasn't restricted swimming in the entire lake since 1998.
"We don't close the lake," says Tom Skelly, manager of CWLP's water division. "We tell the public to use common sense--their best judgment. If the water is dirty or brown, it's best not to swim."
This discretionary approach was devised in conjunction with a 1998 campaign to raise community awareness about leptospirosis--the only corrective actions that could be taken since no cause was ever cited. Skelly attributes the epidemic to "just bad timing," with heavy June rains falling before a triathlon in which more than 850 people swam a mile and a half through "very brown" water. But why the largest outbreak in U.S. history? "We had an awful lot of doctors sitting around a table here trying to figure that out," he says.
Three doctors were dispatched to Springfield from the Centers for Disease Control. They worked in conjunction with another eight researchers at CDC headquarters in Atlanta. The investigative team was coordinated by Springfield Clinic's Donald Graham and included three doctors from the state department of health and another from the city health department. Also lending a hand were Carole Bolin, a leptospirosis expert from the National Animal Disease Center in Ames, Iowa, and another doctor from the Wisconsin Division of Health.
"The medical community was stunned that these people had leptospirosis," recalls Paul McDevitt, organizer of the Ironhorse Triathlon, which has been held in Springfield every June since 1982.
In all, 28 people were hospitalized because of high fever, including one triathlete who had kidney failure. Two others had gall bladders needlessly removed because their doctors failed to recognize leptospirosis. One of the worst-hit triathletes was Bernard Lyles of Chicago, who was wracked with convulsions and had to be put on ice to bring down his 109-degree fever. His doctors said he was close to death.
At the outset Graham and Bolin told the State Journal-Register they were optimistic the cause would be found, given the enormous size of Lake Springfield in contrast to the rivers and ponds associated with previous outbreaks. Bolin had traced a 1995 leptospirosis epidemic affecting at least 2,000 people in Nicaragua to dogs that had contaminated a river. Host animals serve as lepto factories, spewing enormous quantities of bacteria into the environment through their urine.
Investigators spent months testing the blood or urine of every animal they could find in the lake's watershed: 39 horses and donkeys, 131 cattle, 15 pigs, 14 dogs, 8 sheep, 4 llamas, and 2 goats. They also tested 33 deer killed by hunters or vehicles, as well as 16 raccoons, 9 oppossums, and 3 muskrats. But when test after test came back negative, they began to focus their energies on some exotic animals in a small Chatham zoo whose owner had resisted testing. "The strain of leptospira bacteria was so unusual you had to have some unusual mammals causing it," explains Graham.
The horses, llamas, and donkeys at the Grindstone Valley Zoo had already tested negative, as did a water sample from its creek, which empties into the lake. But Brad Reynolds, owner of the rudimentary zoo, would not allow testing of his hippopatamus and kangaroos for fear that tranquilizing them to take samples might kill them. He accused the city of trying to pin the blame for the outbreak on him. Not long after the investigation began, he closed the zoo for good.
The CDC's lead investigator, Juliette Morgan, doubts that the zoo was the source of the leptospira, however. She reasons that if any of the animals had been infected, the other animals would have tested positive, not only because of their proximity but because of the widespread contamination of the lake. "One hippo peeing into the lake probably wouldn't have been enough," she says.
Early on, rumors had spread that failing septic tanks were the problem. For the previous three years the Springfield City Council had been considering requiring new septic owners to have their tanks regularly inspected. In the Lake Springfield area, inspectors found that 49 percent of septic tanks were failing in 1998, which could result in untreated sewage going into the lake. That would explain high bacteria readings, since feces contain E. coli and other bacteria. The council approved the measure within three months of the outbreak.
The city also called for a three-year feasibility study of providing sewer service all around the lake. The study put a $27 million price tag on the project due to the numerous pumping stations required to service the hilly terrain. Currently only 298 lake properties out of 765 are connected to a sewer, with the rest on septic.
But from the start investigators dismissed septic tanks as the source of leptospira. "Septic tank leakage poses more of a threat of general bacterial contamination than leptospirosis," Graham says. "Even though we found numerous violations, we couldn't relate that to leptospirosis."
That's because septic tanks contain human waste, and the investigators were focused on animals. Animals can release large amounts of leptospira in their urine for months, whereas people are poor hosts for the bacteria, excreting only small amounts for a few days. Skelly says the doctors also told him that leptospira cannot live in a septic or sewage environment.
But Donald Reasoner, chief of the U.S. Environmental Protection Agency's microbial contaminants branch, maintains that sewage cannot be discounted as a source, even though as a parasite leptospira does thrive better in a host animal. He says failing septic tanks could conceivably harbor lepto if a lot of people living around the lake became infected.
A more likely source, Reasoner says, is sewers. He points out that leptospirosis is an occupational hazard for sewer workers because of the rats that regularly travel the pipes, urinating as they go. That fact is also mentioned on the CDC's Web site as well as on many others that disseminate information about leptospirosis. Yet, according to Skelly, sewers were never considered or even mentioned by the investigators as a possible source of leptospira.
When asked whether sewage could be the cause, Graham responds without hesitation: "I don't think sewage has anything to do with it." He had not considered the possibility of sewer rats. While he grants that rats can excrete large amounts of lepto, hesayshe was unaware of any sewers at the end of the lake where the triathlon was held. Informed otherwise, he maintains that rats were nonetheless an unlikely source of Springfield's outbreak, because there was "no sewer leak discovered" at the time. "Rats have been there forever," he says. "You have to look for a single event to explain such an unusual outbreak."
As to whether lepto can live in sewage, the CDC's Morgan says she has no reason to believeit couldn't. At the mention of sewer rats, she says, "That's a great point you bring up. It is well known that people who work in sewers are at risk." Sewers were not considered in the Springfield case, she explains, because "it was not obvious" there were any sewer mains at the sparsely populated end of the lake where most people were contaminated.
The primary areas around Lake Springfield that receive sewer service are the University of Illinois at Springfield and Lincoln Land Community College, as well as surrounding neighborhoods not far from CWLP headquarters and the Spaulding Dam. Sewer lines actually cross under water at the Lindsay Bridge and several inlets. Unbeknownst to Graham and Morgan, sewers are also found at the wilder end of the lake, where Sugar Creek feeds in from the south and Lick Creek flows in from the west. Cradled between these two creeks is the town of Chatham, which has experienced rapid growth in the last decade.
It is in this double-pronged end of the lake west of the I-55 bridge crossing that the high E. coli readings are usually registered. Bridgeview Beach, in the branch fed by Sugar Creek, was the site of the triathlon in 1998, and it was the only area of the lake to yield a water sample testing positive for pathogenic leptospira. The city had moved the triathlon in the 1990s from its original site near the Lindsay Bridge to this less congested area because of the burgeoning size of the race. As a result of the lepto incident, the triathlon was returned in 1999 to the Lindsay Bridge.
A pumping station just behind Bridgeview Beach forces sewage from the state police headquarters and several subdivisions south through a small force main, a pipe designed for pumping sewage uphill. It empties into a larger 18-inch main that carries the sewage downhill from the Ball and Glenwood schools west toward Chatham, crossing over the lake beneath Glasser Bridge, about a mile south of Bridgeview.
Once across the lake, this sewage is then pumped through a force main that skirts Chatham's east side and empties into a 30-inch pipe to the north of Chatham. Installed in 1978, this large concrete pipe carries Chatham's sewage along Polecat Creek. Numerous sewer pipes cross under the creek to hook up to it.
Polecat Creek empties into the other branch of Lake Springfield not far from the mouth of Lick Creek near Piper Glen. At this point the large sewer main crosses underneath Polecat and Lick Creeks to continue on north along Veterans Parkway. According to Chatham engineer Jay Jesson, it is now close to capacity.
Storm sewers are not connected to sanitary sewers in Chatham or around Lake Springfield. However, storm water does find its way in through cracks, manhole covers, and illegal hookups of storm lines to sanitary sewers, according to Robert Leinweber, an engineering technician with the Springfield Metro Sanitary District. "There are a lot of ways the water can get in," he says, particularly in older pipes.
Rainwater inside the pipe could accelerate any leaking of sewage that might be taking place through cracks, if groundwater pressure outside the pipe does not squelch it. Any sewage that escapes into the soil before or during a rain could be washed into the lake, along with any rat urine that might be present. This scenario would account for both lepto and E. coli.
Leinweber says flow monitors at pumping stations can alert sanitary district technicians to major leaks, but minor leaks would be very difficult to detect. "With hundreds of miles of sewer lines," he says, "there's no way we can keep track of all leaks." Leaks are typically pinpointed by eyeballing the difference in flow between two adjacent manholes; consequently, repairs are made only when there is a noticeable change in flow.
Emil Cook, head of the water and wastewater department at the engineering firm of Crawford, Murphy & Tilly, says sewer systems in every community are subject to undetected leaks. "It's a phenomenon we deal with every day in our business," he says. "Sewer systems are not expected to stay bottle-tight over time. That just doesn't happen. As they deteriorate, you're going to have infiltration that occurs from rain events and so forth."
Even a major rupture of a force main in August 2000 went unnoticed by the Springfield Metro Sanitary District. After dead fish were reported in Sugar Creek downstream from the lake and Spaulding Dam, Illinois Department of Natural Resources biologist Dan Stephenson investigated a brushy ditch behind the Crowne Plaza Hotel. There he discovered a sewer pipe gushing like "an Old Faithful geyser," he says. By that time, the sewage had killed fish for three miles down the creek. According to Illinois EPA documents obtained through the Freedom of Information Act, the sanitary district was forced to pay $13,864 to cover the costs of 36,947 dead fish and the investigation into their death.
The sanitary district doesn't keep records of sewer main repairs, according to Leinweber,so he couldn't say whether there was a leak in the summer of '98. After checking with his boss, sanitary district director Andy Alves, Leinweber told me no one could recall a major sewer main break in the lake's watershed for well over ten years.
But EPA documents show that just last October a cracked force main leaked sewage into a tributary of Lick Creek, which empties into the lake. A construction crew installing a new force main along Veterans Parkway discovered the leak in a wooded area north of the Panther Creek subdivision. Workers noticed a foul odor for four or five days before they found the cause and alerted the sanitary district.
The sanitary district divvies up responsibility for sewer repairs around Lake Springfield with the city's Office of Public Works. Leinweber says there is often confusion within the agencies about which one should handle a sewer call. When that happens, they consult a map of Springfield showing county property in blue and city property in white. A glance at the lake shore on this map reveals a haphazard checkerboard of blue and white lots.
Another possible conduit for rat urine into the lake is storm sewers, which are easier for rats to get into than sanitary sewers. Chatham's storm sewers empty directly into Sugar and Polecat creeks, while others in the watershed empty directly into Lake Springfield.
Sewers are favorite haunts of rats because the pipes supply food and water as well as an underground passageway hidden from human eyes. Rats require much more water than other rodents, which is why they travel along waterways. They are adept at extracting grease, kitchen scraps, and undigested food from sewage while avoiding or adapting to any poisons. Indeed, they can learn to eat rat poisonfor food with no apparent ill effects.
Even though poison is set out regularly in Springfield's sewers, rats still inhabit them, says Mike Wallner, the city's superintendent of sewers. Sewer workers occasionally come across one when they are in a manhole, and the rodents often make an appearance above ground when garbage is left in the streets.
For the most part, they do us the favor of keeping out of sight until nighttime, when they come out to scavenge our refuse. They breed rapidly in colonies located in sewers, garbage dumps, or in linking burrows dug into the sides of ditches and creeks. Being partial to grain, they are also often found around farms. In short, rats are wherever there is an ample food supply, and there is much to entice them in the Lake Springfield watershed.
At a 1998 town meeting about the leptospirosis epidemic, residents wondered whether human sewage in Sugar Creek upstream of the lake could be a source of leptospira bacteria. Graham acknowledged the creek was contaminated but assured them it was unconnected to the outbreak.
Today Graham recalls the sewage came from Auburn's treatment plant, which releases treated waste into Sugar Creek about eight miles upstream from Lake Springfield. "There was visible junk with tons of bacteria," he says. "If you talk to people who live along the creek, they'll tell you there's a stench when the weather is warm. We didn't think that was necessarily good, but we couldn't relate it to leptospirosis."
If sewage is not treated properly, it could supply fodder for rodents living along the creek banks. EPA documents show the Auburn plant has had 17 violations for their discharge since February 2001; in September 2001, the plant exceeded its limit on suspended solids by as much as 229 percent. But it had no violations in 1998--indeed, no violations for the years 1997 through 2000. Roger Callaway, manager of Illinois EPA's compliance monitoring unit, verifies this four-year gap in violations, adding that during this time the Auburn plant had reported monthly readings as required.
The creek also receives effluents from some of the residents along its banks who have aeration septic systems, which must be installed where clay soils can't absorb the waste. About a third of septic systems in Sangamon County are aeration. Their effluents are touted to be colorless and odorless, but these units are more prone to failure than regular septic tanks. While residents around the lake have been required since October 1998 to have new aeration systems inspected twice a year to prevent contamination of the lake, people living along the feeder creeks are not subject to this requirement.
Wildwood Estates, a new Chatham subdivision on the east side of Sugar Creek, was intended to have septic systems until the City of Springfield took Chatham to court to stop the development, citing its potential to pollute the lake. The matter was resolved in April when Chatham agreed to install sewer service there, which will require a costly pumping station and force main. This force main will run north along I-55 and connect to the 18-inch trunk line that crosses over the lake at Glasser Bridge.
An added attraction for rodents in the creeks emptying into Lake Springfield is the runoff of livestock manure and fertilizers. These boost algae growth and its subsequent decomposition, forming a nest for insect larvae, which are rat delicacies. What's more, decomposition is abetted by the extremely slow flow of Sugar Creek.
Any putrefying mass is a magnet for rats and mice, which is why they are often spotted around garbage. In the year following Springfield's leptospirosis outbreak, hundreds of prisoners in the Philippines were laid low with lepto after heavy rains flooded their compound. The source was traced to rats that had infested garbage accumulating near the jail. In this country, inner-city dwellers are at risk for leptospirosis because of the prevalence of rats there.
Curiously enough, residents at the 1998 town meeting asked whether garbage and trash near the lake could be a source of leptospira. Random dumping of garbage in ditches along country roads and creeks has been a chronic problem at least since the 1990s, according to Sangamon County's environmental health director, Jim Henricks.
One homeowner near the Sugar Creek Covered Bridge Historic Site complains that people have been dumping their bags of trash there for years. When the bridge was raised and restored about nine years ago, his cat caught several rats near the creek after the construction disturbed their burrows. But he--like most people--normally never see rats.
Rodents have long been hidden vehicles of disease. They carried the plague bacteria in the Middle Ages, and even though Europeans didn't know that, they learned by the 17th century to scour their waterways and sweep the streets of garbage whenever plague threatened. Towns that mandated community cleaning days were often spared the epidemic.
Despite centuries of futile attempts to exterminate them, rodents continue to serve as red flags for human negligence and congestion. It is likely that the rat population in the Lake Springfield watershed has increased with the influx of people into Chatham and Auburn, though no one can vouch for it. Even today it might be worthwhile to test rats and mice in the area for lepto. In addition to sewers leaking rat urine, there's a possibility that the unusually heavy rains in June '98 flooded rodent burrows along Sugar and Lick creeks, releasing a torrent of lepto-laden urine into the lake.
Considering that Lake Springfield provides the city's drinking water, it seems risky to continue discounting the high bacteria levels as a normal consequence of heavy rainfall. Though the drinking water is treated to kill bacteria, EPA documents indicate that twice since 1990--in the summer of 1992 and in March of 1999--bacteria was present in more than the limit of five out of 100 water samples taken monthly by CWLP.
Just about everyone consulted for this article repeated the mantra that leptospirosis is a danger in any open body of fresh waterand that Springfield's outbreak was the result of an unlucky confluence of factors--a lot of people were in the water after a very heavy rain. The likelihood of it ever happening again, they say, is small. But was it just a fluke? Or is Springfield in a state of mass denial?