DEC 23, 2022 10:08 AM PST

Finding the Route Lyme Pathogens Take Through the Body

WRITTEN BY: Carmen Leitch

While about 30,000 Americans are confirmed to have Lyme disease every year, the Centers for Disease Control and Prevention (CDC) has estimated that the number could be as high as 476,000. Lyme disease is also becoming more common in other countries, with an estimated 200,000 cases in Western Europe every year. Ixodes tick bites transmit the bacteria that cause Lyme disease; these pathogens are varieties of Borrelia bacteria, including Borrelia burgdorferi in the US and B. afzelii and B. garinii in Europe. The disease causes rash, fever, joint pain, and can lead to nervous system and heart complications.

A digitally colorized SEM image at high magnification, depicting three Borrelia burgdorferi bacteria, derived from a pure culture. / Credit: CDC/ Claudia Molins / Photo Credit: Jamice Haney Carr

Now scientists may have learned how Borrelia bacteria migrate from the site of a bite to an infected person's bloodstream. For this work, researchers created a specialized 3D tissue model that was meant to mimic a human blood vessel, the skin around it, and the tick bite. High-resolution optical imaging was used to monitor the bacteria. This showed that  B. burgdorferi basically uses trial and error to find an opening in spaces called junctions, which line blood vessels and can be found near the sites of bites. Once the pathogenic microbes break through, they can move into the bloodstream and on to other tissues and organs. The findings have been reported in Advanced Science.

If Borrelia could not find a junction right away, they kept searching until they found one, said senior study author Peter Searson, a professor at the Whiting School of Engineering of Johns Hopkins University. "The bacteria spend an hour or two using this behavior to find their way into the blood vessels, but once there, they are in circulation in a matter of seconds."

Understanding how these bacterial pathogens spread could help scientists develop treatments for Lyme disease, which can cause symptoms that last for months or even years. It may be possible to prevent the pathogens from moving beyond the site of the initial bite.

The researchers have experience developing vascular models with tissue engineering, and they applied what they knew to make a dermal tissue model.

"We also believe that the kind of human tissue-engineered model we created can be broadly applied to visualize the details of dynamic processes associated with other vector-borne diseases and not just Lyme disease," Searson added.

Sources: CDC, WHO, Johns Hopkins University, Advanced Science

About the Author
Bachelor's (BA/BS/Other)
Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
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