New Cause for Lyme Disease Complicates Already Murky Diagnos

New Cause for Lyme Disease Complicates Already Murky Diagnos

Postby Oscar » Wed Feb 17, 2016 10:06 am

New Cause for Lyme Disease Complicates Already Murky Diagnosis

[ http://www.scientificamerican.com/artic ... iagnosis1/ ]

Scientists claim a novel bacterium causes some different symptoms, adding to the body of research showing the complexity of the disease

By Melinda Wenner Moyer on February 16, 2016

Tick-borne Lyme disease in the U.S. has long been thought to be caused by a single microbe, a spiral-shaped bacterium called Borrelia burgdorferi. Last week this notion was challenged when a team led by scientists at the Mayo Clinic discovered that Lyme could be caused, albeit rarely, by a different bacterial species that may incite more serious symptoms ranging from vomiting to neurological issues. Scientists working in the contentious field of Lyme disagree, however, as to what this information means for public health and if these findings are truly the first of their kind. For years, they say, research has pointed to the notion that the spirochete that causes Lyme disease in the U.S. is more heterogeneous than many have acknowledged.

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All these scientific challenges could help explain why there are so many rifts within the Lyme research community. The organism is difficult to study and genetically diverse, and its ecology—the complicated and intricate dance that takes place between the ticks, their spirochetes and their numerous animal and human hosts—is immensely difficult to track and understand. “To me, the underlying biology that paves the way for controversy and vastly different perspectives is all a function of the amazing complexity and sophistication of Borrelia,” Ostfeld says. Adding to the problem, scientists bring to the field different backgrounds, methodologies, standards of evidence and preconceptions.

The new bacterium could complicate the diagnosis of Lyme, too, which has long been a contentious issue. Even with B. burgdorferi–caused Lyme, government-recommended diagnostic tests do not typically work in the first four weeks of infection; blood antibody levels are too low. (Three of the six patients who had B. mayonii in the Mayo Clinic study would have failed the standard Lyme tests based on their antibody results.)

Because of these difficulties, physicians diagnosing Lyme in its early stages are supposed to rely entirely on clinical cues such as the characteristic bulls-eye rash, fever, aches and fatigue. But what if a patient is vomiting and has a spotty rash? “People may not think of a tick-borne disease with that,” Aucott says, so cases of B. mayonii may go undiagnosed and untreated. (B. burgdorferi–caused Lyme disease, he adds, does not always cause a bulls-eye rash either.) Pritt and her colleagues recommend that physicians use their PCR (polymerase chain reaction) test to diagnose B. mayonii early on, as these bacteria, unlike B. burgdorferi, proliferate readily in blood. But Aucott points out that these tests require physicians to send samples to the Mayo Clinic, and “that just may not happen.”

According to the study, only six Americans since 2012 have been infected with B. mayonii. Looking at its evolutionary tree, the spirochete is probably not a new organism, Qiu and Ostfeld say; it has likely been lurking in small numbers in the environment for a long time, and may stay that way. Or it may become more common and spread geographically as other tick-borne diseases have done in recent years, thanks to various ecological factors. Although many questions remain, one thing does seem clear about the new finding: It is yet another paper to add to the pile suggesting that Lyme is not always a simple or straightforward beast. “It’s really not,” Lane says. “I can state that unequivocally.”
Oscar
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