Canadians first to illustrate Lyme disease bacterium
Published Wednesday, July 2, 2008 4:27PM EDT
Canadian researchers are the first in the world to use high-resolution, 3-D imaging to create dramatic new footage of the bacterium that causes Lyme disease as it moves through the bloodstream of a living host.
Microbiologists at the University of Calgary have been able to create a fluorescent strain of the bacterium Borrelia burgdorferi and observe its movement in mice.
B. burgdorferi is part of a group of bacteria known as pathogenic spirochetes, which cause a variety of bacterial diseases such as syphilis, leptospirosis and relapsing fever, as well as Lyme disease.
Until now, scientists have been unclear how these bacteria move from the blood to tissues in the body.
However, the ability to view the spirochete will allow scientists to better study and understand how these and other bacteria spread through the human body and lead to disease.
"When you get a tick bite, the spirochete gets into the blood and then hitchhikes through the body, gets out of the blood system and then gets into the heart, neurological tissue in the brain and in the joints," Dr. George Chaconas, one of the lead researchers, told CTV News. "So this is its way of getting transportation around the body."
The image of the bacterium was published in the journal PLoS Pathogens.
The new breakthrough comes at the beginning of the peak season for Lyme disease. Each year, about 23,000 new cases of Lyme disease are diagnosed in the United States. About 100 new cases are diagnosed in Canada.
Humans contract Lyme after they are bitten by an infected tick.
According to the Public Health Agency of Canada (PHAC), Canadians can get Lyme disease from two sources: the western blacklegged tick, which is found in British Columbia, and blacklegged ticks, which are found in southern and eastern Ontario, southeastern Manitoba and areas of Nova Scotia.
Early symptoms of Lyme disease include:
- A circular rash near the area of the tick bite
- Fatigue, chills and fever
- Headache, as well as muscle and joint pain
- Swollen lymph nodes
If left untreated, Lyme disease can lead to nervous system disorders, various neurological symptoms, arthritis or arthritis-like symptoms and extreme fatigue.
Prevention methods include wearing long-sleeved shirts and pants and tucking pants into socks or boots; using a bug spray containing DEET; and inspecting clothes and skin for ticks after being outside.
Lyme disease is diagnosed after a blood test identifies antibodies the body produces in response to the bacteria. A patient who is in the early stages of the disease can then take antibiotics to clear the bacteria. However, Lyme is harder to treat as it advances through the body.
Some Canadians are concerned that people who have symptoms of Lyme disease are not always taken seriously by doctors and are therefore not tested for the bacterium.
Protests are scheduled to take place in cities across the country on Friday. The aim of the protests is to advocate for better testing methods, more awareness of the disease and a better warning system for the public.
While the United States Centers for Disease Control has a detailed map on its website of where infected ticks can be found in the U.S., no such map exists in Canada. As well, the Canadian Lyme Disease Foundation believes that far more than 100 new cases of Lyme disease occur in Canada each year.
Mary deLisser fell ill in 2002 after camping in a park in Courtney, B.C. She came down with flu-like symptoms, including pain and fever, and developed short-term memory loss. A doctor at a walk-in clinic missed the signs and it wasn't until 10 months later that she found Dr. Ernie Murakami, who diagnosed her with Lyme disease within days.
Because her illness was already at a later stage, her round of antibiotics has not completely eradicated her symptoms.
"Since I've been treated I'm still left with a considerable amount of pain, although it's a lot better than it was," deLisser told CTV News.
"And I still have the terrible fatigue and the cognitive difficulties that get worse as the day goes on."
DeLisser said that PHAC should be tracking the disease more carefully and should have warnings about Lyme disease in places like public parks.
Robbin Lindsay, a research scientist at PHAC, said the agency has noticed that tick populations are expanding into provinces where they haven't been seen before. The agency is also working on ways to better inform people of the risks of contracting the disease.
"I suspect that in the next year or so, we will have maps like that available for general viewing by the public and for physicians to know where the ticks are established," Lindsay told CTV News.
Another problem for patients is that they could suffer for months, as deLisser did, or even years because doctors don't know enough about the disease and so don't think to test for it.
"It's under the radar here, perhaps under publicized and not enough people know about it. And in the case of Lyme disease, the best approach to dealing with it is prevention," Chaconas said.
With a report by CTV medical correspondent Avis Favaro and senior producer Elizabeth St. Philip
Real-Time High Resolution 3D Imaging of the Lyme Disease Spirochete Adhering to and Escaping from the Vasculature of a Living Host
Tara J. Moriarty, M. Ursula Norman, Pina Colarusso, Troy Bankhead, Paul Kubes, and George Chaconas
Pathogenic spirochetes are bacteria that cause a number of emerging and re-emerging diseases worldwide, including syphilis, leptospirosis, relapsing fever, and Lyme borreliosis. They navigate efficiently through dense extracellular matrix and cross the blood-brain barrier by unknown mechanisms. Due to their slender morphology, spirochetes are difficult to visualize by standard light microscopy, impeding studies of their behavior in situ. We engineered a fluorescent infectious strain of Borrelia burgdorferi, the Lyme disease pathogen, which expressed green fluorescent protein (GFP). Real-time 3D and 4D quantitative analysis of fluorescent spirochete dissemination from the microvasculature of living mice at high resolution revealed that dissemination was a multi-stage process that included transient tethering-type associations, short-term dragging interactions, and stationary adhesion. Stationary adhesions and extravasating spirochetes were most commonly observed at endothelial junctions, and translational motility of spirochetes appeared to play an integral role in transendothelial migration. To our knowledge, this is the first report of high resolution 3D and 4D visualization of dissemination of a bacterial pathogen in a living mammalian host, and provides the first direct insight into spirochete dissemination in vivo.