My dog has better tick protection than I do - but that could change soon

Lyme disease is on the rise. But scientists are searching for ways to prevent it.

Each time I pull out a wriggling tick from my dog's fur, I flash back to my own brush with Lyme disease – a bacterial infection spread via tick bites. I never found the deer tick that bit me, but I remember the flu-like chills, the body aches and signature bullseye rash that ran up and down my arm. A month of intense antibiotics cleared the infection and I haven’t had any further problems, but other people aren't so lucky.

In addition to an oval or circular rash, Lyme disease can cause flu-like symptoms. Infections that go untreated in the short term can lead to potentially debilitating issues in the months and years that follow, such as fatigue, body aches or nerve damage.

Meanwhile, there are an estimated 476,000 cases of Lyme disease diagnosed in the US every year – and as ticks expand their territory, that risk is growing. In the US, there are currently no licensed vaccines to prevent Lyme disease in people – but that might be about to change. And scientists are developing other strategies to help prevent infections, too. This is the battle against a group of particularly resilient bacteria and their spider-like host – and it's heating up.  

"We are seeing many more patients, many more people actually getting infected," says Thomas Hart, assistant professor of molecular microbiology and immunology at Johns Hopkins Lyme and Tickborne Diseases Research and Education Institute, Maryland. "It's a good time for there to be a new preventative."

A public health threat on the rise

Tick populations are expanding their range throughout Europe and the US, thanks to expanding forest and deer populations and climate change creating milder winters. And while tick season usually stretches from spring to autumn in many places, climate change is now increasingly leading to longer, sometimes year-round tick activity.   

Ticks carry a number of pathogens that can infect people, leading to diseases that include encephalitis, anaplasmosis and babesiosis, among others. But Lyme disease, caused by some types of Borrelia bacteria, is the most common tick-related illness in Europe and North America.

To this day my labrador Walter continues bounding around in long grass, unscathed by the illnesses ticks carry. He is vaccinated against Lyme disease and eats his monthly chewable tablet, smothered in spray cheese, to ward off fleas, ticks and heartworm – a disease spread via mosquito bites.

Currently there are several anti-tick treatments for dogs and cats, which often rely on chemicals that kill ticks once they start to feed. Typically these are either applied directly to the skin as a "spot-on" treatment, disseminated via a collar, or delivered as a tablet.  

Developing preventative drugs for humans, on the other hand, is no easy task. Studies in people are harder and more costly to run than those in animals. For trials in people, scientists often need to recruit a large number of participants and follow them over time as they go about their lives. That's because only a small fraction of them will get bitten and develop a tick-borne disease, and there need to be enough infections to show if the vaccine or drug works.

In animal trials, meanwhile, researchers often put infected ticks directly on them, almost ensuring that they will get infected with a given tick-borne pathogen, making the trials easier to do. But scientists hesitate to use so-called........

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