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Ticks spread the bacterium behind Lyme disease - but symptoms can persist even when the bug seems to have gone.Medical-on-Line/AlamySome patients with Lyme disease still show symptoms long after their treatment has finished. Now proteins have been discovered that set these people apart from those who are easily cured.
People who experience the symptoms of Lyme disease, which include fatigue, soreness and memory or concentration loss, after treatment for the disorder are sometimes diagnosed as having chronic Lyme disease or post-Lyme disease syndrome. But these diagnoses are difficult to make, because the individuals no longer seem to harbour the bacteria that cause Lyme disease. And the symptoms could instead be indicative of chronic fatigue syndrome or depression.
Now Armin Alaedini at Weill Cornell Medical College in New York and his colleagues have found that patients diagnosed with post-Lyme disease syndrome have antibodies that suggest they carried the infection for an unusually long time. The finding, published in Clinical Immunology1, might help the syndrome to be better understood, diagnosed and treated.
Alaedini's team looked at antibodies made in response to a protein called VlsE, which is found on the surface of Borrelia burgdorferi, the tick-borne bacterium that causes Lyme disease.
The antibodies recognize a snippet of the protein called an epitope, and recruit the immune system to attack the bacterium. The researchers found that post-Lyme sufferers have a greater variety of antibodies to this epitope than patients whose infection cleared up quickly.
This finding suggests that patients with chronic symptoms have experienced a prolonged infection, caused by microbes that have evaded the immune system by varying the epitopes they carry. As a result of these variations, the body makes new antibodies targeting the modified protein. The longer the microbe manages to keep changing, the more diverse its host's antibodies become.
Some post-Lyme sufferers had varied antibodies against VlsE epitopes despite being diagnosed and treated early, says Alaedini. "That could mean they naturally have a different antibody response to the infection than most people; it could mean they weren't treated properly; or it's possible they were reinfected and the second infection was never treated," he says.
"This is the first study I've seen that shows some immunologic difference between someone who resolves their Lyme and someone who develops post-Lyme disease syndrome," says Linda Bockenstedt, a rheumatologist and immunologist at Yale School of Medicine in New Haven, Connecticut.
The presence of varied antibodies hints that the chronic symptoms could be caused by an ongoing inflammatory response caused by antibodies mistakenly reacting to the body's own proteins, Bockenstedt suggests.
"The big question to me is whether this can lead to an autoimmune phenomenon," says Bockenstedt. "But if that were the case, I'd expect the disease to worsen without immune-modulating treatment, and it doesn't."
Alaedini suggests that higher levels of antibodies could increase the body's levels of cytokines, immune-system proteins that can trigger the symptoms experienced by patients with post-Lyme disease syndrome. "Various cytokine profiles have been associated with fatigue, anxiety and depression," he explains.
If these antibodies are unique to people with chronic Lyme disease, it could lead to a test and treatments for the disorder, Alaedini says. It could also guide treatment of the disease itself. "If patients with an acute infection develop antibodies to these epitopes, perhaps they require a more aggressive course of therapy," he adds.
But a predictive marker won't be useful without new therapies for the persistent symptoms, says Henry Feder Jr, a physician specializing in infectious diseases at the University of Connecticut Health Center in Farmington. If an immune response problem leads to the syndrome, antibiotics won't help. "I guarantee you that if you tell a patient they won't feel better after antibiotics, they won't," Feder says. "We need to know what's going on."
CHAMPAIGN, lll. — A new study offers a detailed look at the status of Lyme disease in Central Illinois and suggests that deer ticks and the Lyme disease bacteria they host are more adaptable to new habitats than previously appreciated.
A new study found a potential new reservoir of Lyme disease: the prairie vole (Microtus ochrogaster). | Photo by Michael Jeffords, Illinois Natural History Survey
Led by researchers at the University of Illinois, the study gives an up-close view of one region affected by the steady march of deer ticks across the upper Midwest. Their advance began in Wisconsin and Minnesota and is moving at a pace of up to two counties a year in Illinois and Indiana.
Today the deer tick is established in 26 Illinois counties, up from just eight in 1998, said Illinois Department of Public Health entomologist Linn Haramis. Reports of human Lyme disease cases in the state have more than tripled in the same period, he said.
“We’ve had several years in a row where we’ve had over 100 cases, up from about 30 per year more than 10 years ago,” Haramis said. “It’s not a huge increase, but it’s been steady and there’s an upward trend.”
Deer ticks are known to do best in forested areas, where they can readily move from small mammals (which provide their first meal) to moist leaf litter on the forest floor, and then to deer, on which they mate. Deer ticks do not pick up the Lyme infection from deer, said Jennifer Rydzewski, who completed her master’s degree with the study in the department of natural resources and environmental sciences at the University of Illinois.
“The deer tick will feed on a variety of mammals, birds and even reptiles,” she said. “But Borrelia burgdorferi, the bacterium that causes Lyme disease, replicates really well within white-footed mice, so white-footed mice are the main reservoir that passes that bacterium on to the immature ticks that are feeding on it.”
White-footed mice also are forest dwellers. Prior to the new study, little was known about whether, or how, Lyme disease persists in other habitat types.
To determine if Lyme disease had gained a foothold in the patchwork of forests, farms and prairies of Central Illinois, researchers trapped small mammals in Allerton Park, a 1,500-acre (600-hectare) natural area in Piatt County. They focused on four habitat types: young forest, mature forest, a flood plain and a 30-acre (12-hectare) patch of prairie surrounded by woods and agricultural fields.
The researchers removed deer ticks from the mammals they trapped and tested the ticks for Lyme disease.
They found that the immature forest and the prairie hosted the highest percentage of deer-tick-infested mammals, the highest number of ticks per mammal trapped and the highest rates of ticks infected with Lyme disease of the four habitat types evaluated.
“The highest prevalence of B. burgdorferi infection was found (in deer tick larvae) from the prairie (27 percent) followed by the young forest (15 percent), the mature forest (6 percent) and the flood plain (6 percent),” the researchers wrote.
“Interestingly, all of the positive ticks from the prairie were from prairie voles, not the typical white-footed mouse,” Rydzewski said. There also were many more ticks per animal on the prairie voles than on the white-footed mice of the forest, she said.
This is the first study to report evidence that the prairie vole may potentially serve as a competent reservoir host for the Lyme disease bacterium, B. burgdorferi, said Nohra Mateus-Pinilla, a wildlife veterinary epidemiologist at the Illinois Natural History Survey who led the study with Rydzewski and natural resources and environmental sciences emeritus professor Richard Warner. (The Survey is a unit of the Prairie Research Institute at Illinois.)
“The fact that we found tick larvae feeding so prominently on prairie voles and those ticks were infected and hadn’t had a chance to feed on anything else is a very strong indicator that we are dealing with a different reservoir of Lyme disease that deserves more attention,” Mateus-Pinilla said.
The researchers hypothesize that when newly hatched ticks find themselves on the prairie, they latch on to the first small mammal that comes along, which in most cases is a prairie vole (white-footed mice prefer the forest). The abundance of prairie voles in the prairie is much lower than that of the white-footed mice in the forest, so more tick larvae and nymphs end up on the same few prairie voles. Since the number of ticks per animal is higher on the prairie, the likelihood of infection is higher there as well.
“The landscape of Illinois, especially the northern and central area, is very fragmented with agricultural and other development, so there aren’t really big continuous areas that are forested,” Rydzewski said. “And so maybe these ticks are finding new habitats to establish themselves in because of the lack of previous habitats.”
“What’s exciting about the new findings is that we are dealing with potentially new mechanisms of disease transmission that we just have not explored and perhaps we do not understand,” Mateus-Pinilla said. “We need to think outside of what we already know about Lyme disease transmission.”
The new study appears in the journal Vector-Borne and Zoonotic Diseases.
Researchers from the U. of I. department of pathobiology and Michigan State University also contributed to this study.
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WEDNESDAY, July 6 (HealthDay News) — Move over, Lyme disease: Another tick-borne illness is on the rise in various parts of the country, and this one can kill.
Known as babesiosis, the disease is caused by a microscopic parasite that attacks blood cells, causing flu-like symptoms that can make it difficult to accurately diagnose. Like Lyme disease, which is caused by bacteria, babesia microti parasites are carried by deer ticks.
First documented in Massachusetts in 1969, the once-obscure babesiosis has surfaced as a significant public health threat in parts of the Northeast and Upper Midwest over the last several years. A recent study in the journal Emerging Infectious Diseases, published by the U.S. Centers for Disease Control and Prevention, revealed that between 2001 and 2008 cases climbed from six to 119 in New York's Lower Hudson Valley -- a 20-fold regional increase.
And many cases may be escaping detection, experts say.
"I think it's underreported. One of the reasons we're seeing more about it is because people are becoming more aware," said Dr. Peter Krause, a babesiosis researcher and senior research scientist at the Yale University School of Public Health. "The theory is that it's spreading from east to west, as if you were dropping a pebble in a pond and it spread outward geographically."
About 1,000 cases are reported annually in affected locales, Krause said, but many people with babesiosis have no symptoms and never know they're harboring the parasite. For others, symptoms can include high fever, severe headache, fatigue, chills, and muscle aches and pains. It is treated with antimicrobial drugs, such as antibiotics.
People with compromised immune systems -- including the elderly and those with cancer, HIV or no spleens -- are especially at risk of potentially deadly complications such as organ failure. Between 10 percent and 20 percent of patients in those populations die as a result, Krause said.
The more prolific Lyme disease causes similar symptoms in early stage cases but is easier to diagnose by its telltale bullseye rash, said Dr. Barbara Herwaldt, a medical epidemiologist at the CDC who specializes in parasitic conditions.
Deer are pivotal to the life cycle of ticks carrying the babesia microti parasite by serving as a blood meal, shelter and a place to mate, Krause said. Ticks also feed on birds, who serve as carriers for Lyme disease, which affects the entire continental United States. Fortunately for humans, birds don't carry babesia microti.
Krause noted that ticks need a moist climate to thrive, so dry states such as Arizona are not likely to see babesiosis cases caused by tick bites. But the disease can potentially spread to all states in an even sneakier way -- through the blood supply.
Although a blood screening test is in trials, Krause said, donors are currently only asked if they have had babesiosis, and those who harbored it but never showed symptoms can pass it through their donated blood. And because most blood recipients are already physically compromised, babesiosis has about a 30 percent mortality rate in that group, he said.
"Getting babesiosis through the blood supply is a rare event and people shouldn't panic," he said. "I don't think it will reach a crisis level, but it's still a concern."
To help prevent babesiosis, the CDC advises people with compromised immune systems or other vulnerabilities to avoid tick-infested wooded areas, particularly during warm months. The agency also recommends that everyone walk in the middle of trails and avoid bushy areas with lots of leaves or tall grasses and to use the repellent DEET and pre-treat clothes with an insect repellent containing permethrin before going outdoors.
The CDC also recommends doing full-body checks and showering within a few hours of being in the woods, as well as tossing used clothes in the dryer to kill any ticks that might be hiding there.
The authors of the study also advised clinicians to consider babesiosis in patients who have been exposed to ticks or received blood products and who show up for treatment with a fever and anemia resulting from the destruction of red blood cells.
