Don’t get bitten Kent Wood/Science Photo Library

A new test can distinguish between Lyme disease and another tick-borne disease with nearly identical symptoms. This could enable doctors to treat the condition much sooner, preventing its debilitating symptoms from setting in.

Lyme disease – a bacterial infection transmitted by the blacklegged tick (pictured above) – is a major public health problem in the US, with around 300,000 people contracting it each year. Thanks in part to climate change, the ticks that carry the disease are no longer confined to small pockets of the US but are spreading through Asia and Europe, where people aren’t used to recognising its symptoms.

Diagnosis is largely based on the presence of the characteristic “bullseye” skin lesions around the site of a tick bite. However, an identical pattern is caused by a milder disease, southern tick-associated rash illness (STARI). While both are treated using antibiotics, they usually require different types.


Both conditions can give you chills, fatigue and joint ache, but if Lyme disease is left to linger it can cause facial paralysis and inflammation of the brain and spinal cord. This makes it critical to determine which infection a person has as soon as possible.

Early detection

Lyme disease is caused by the bacterium Borrelia burgdorferi. Ticks pick up the bacteria when they feed on infected mouse blood, and pass it onto humans through a bite. Previous tests have attempted to identify antibodies that your body produces to fight the bacteria, but they aren’t reliable at the early stages of infection. There is no diagnostic test for STARI.

When the body gets infected, it can mess with metabolism, affecting the chemicals present in the blood. John Belisle at Colorado State University and his colleagues wondered whether Lyme and STARI could be distinguished by measuring the changes each disease causes to the abundance of specific metabolites in the blood.

To find out, they screened 220 blood samples from people diagnosed with STARI or Lyme disease and compared them with samples from a healthy control group. The diseased samples were collected within six days of the appearance of a skin lesion.

The team identified several differences between the STARI and Lyme samples – including a variation in the level of fatty acids – and trained an algorithm to recognise these differences. When tested on a new set of samples, the algorithm was able to diagnose Lyme disease and STARI with an accuracy of 85 and 92 per cent, respectively. Healthy controls were identified with an accuracy of 93 per cent.

Fighting the spread

“We are working to develop this into a clinical test,” says Belisle. “We hope to have this completed within a year. This will need to be followed with robust clinical trials.”

A representative from UK charity Lyme Disease Action points out that the test may only be relevant to the specific bacterial strains that cause the disease in the US: “As Lyme disease in Europe is different to that in America, this research may not apply to European Lyme disease, which may result in a different set of metabolites.”

Although you may have vaccinated your dog against Lyme disease, no such vaccination exists yet for humans. A vaccine developed by Valneva, a biotech company based in France, is in early human trials. It is hoped that it will protect adults and children against most strains of Lyme disease, by neutralising the bacteria before it circulates around the bloodstream.

Journal reference: Science Translational Medicine, DOI: 10.1126/scitranslmed.aan2415

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