There's a new possible suspect behind the most commonly reported insect-borne illness in the US

Lyme disease, the most commonly reported insect-carried disease in the United States, is caused by a known bacteria found in ticks. But scientists have now found that another parasite may also be responsible for the nasty illness.

As The New York Times reports, researchers at the Mayo Clinic in Rochester, New York, identified six patients who were infected by a newly identified bacteria they named Borrelia mayonii.

The patients had symptoms similar to those caused by Borrelia burgdorferi, which was previously the only culprit behind Lyme disease in the US.

The findings, which were reported in the medical journal The Lancet Infectious Diseases, could help explain why so many people who suffer symptoms of Lyme test negative for it.

Symptoms and causes of Lyme disease

There were more than 25,000 confirmed cases of Lyme disease in 2014, though other sources estimate as many as 200,000 cases. It is transmitted by bites from deer (or black-legged) ticks, and typical symptoms include fever, headache, fatigue, and a telltale "bull's eye" rash.

The disease is often treatable with antibiotics, but if left untreated, it can spread to the joints, heart, and nervous system. (Some people report having lasting symptoms that don't respond to treatment, a controversial diagnosis referred to as post-treatment Lyme disease or chronic Lyme disease.)

In addition to the typical Lyme symptoms, the patients with the new bacteria also had nausea and vomiting, but only one out of the six people studied had the bull's eye rash, the Times reports. The antibiotics used to treat B. burgdorferi infections are reportedly also effective against B. mayonii.

Detecting and preventing infections

So far, the new parasite has only been found in the upper Midwest. Bobbi Pritt, the medical director of the microbiology laboratory at the Mayo Clinic, told the Times that people who have been exposed to ticks in Minnesota and Wisconsin and suspect they may have Lyme disease should get tested for B. mayonii infection.

Scientists have known for some time that Lyme disease can be caused by multiple species of Borrelia bacteria. But this is the first new species discovered in a decade.

Now that doctors know about it, they may be able to diagnose Lyme cases that current tests don't detect.

But prevention is always the best strategy. You should wear insect repellent or long-sleeves when spending time in outdoor, wooded areas, and check yourself thoroughly for ticks when you get home. Your chances of getting the disease are much lower if you remove the tick within 24 to 48 hours.

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