Lyme Disease on Nantucket: A New Approach

For the last four decades, Dr. Timothy Lepore has been the main medical figure on Nantucket, Massachusetts—a small island off Cape Cod. As the head of the emergency room and the island’s only surgeon and medical examiner, he now oversees the only private practice treating numerous patients dealing with Lyme disease. This disease affects about 15% of the island’s residents, causing various symptoms such as fever, rash, facial paralysis, an irregular heartbeat, and arthritis.

Now at 80, Lepore might just retire if a scientific team’s aspirations to reduce Lyme disease transmission on the island succeed. Their goal shifts focus from deer and ticks to wild mice, the primary carriers of the Lyme bacteria. The idea is to genetically engineer mice to be resistant to Lyme disease and release them on Nantucket, limiting the number of disease-spreading mice.

Why Nantucket is Under the Microscope

The Lyme disease issue on Nantucket dates back to 1926 when locals decided to bring in two female deer to keep a lone male buck company. By the 1950s, preservation efforts had placed half the island into conservation, creating the perfect environment for Lyme’s hosts to flourish.

As deer numbers increased, so did ticks, which thrive on the deer. Female ticks feed on them, laying up to 2,000 eggs at a time. While deer themselves don’t get Lyme, they’re often hosts for ticks, helping to spread the disease across the island.

Interestingly, not every tick carries Lyme disease, and a bite doesn’t guarantee infection. For that to happen, the tick usually needs to be attached for over 24 hours. Most people associate Lyme disease primarily with deer and ticks, but the real culprits are white-footed mice. When an uninfected tick bites an infected mouse, Lyme bacteria transfer, enabling the cycle to continue.

Kevin Esvelt, a pioneer in genetic engineering at MIT, explained, “We have created conditions that are perfect for ticks and mice, which has backfired on us.” Lyme disease can be treated with antibiotics, but untreated infections may spread to vital organs and the nervous system, as seen in 33-year-old Shauna Asplint, who first discovered her Lyme disease at age 10. Years later, it resulted in paralysis on one side of her face—a lasting reminder of her battle with the disease.

The Centers for Disease Control and Prevention estimate that Lyme disease affects nearly half a million people annually in the U.S., though it seldom proves fatal.

Scientists’ Ambitious Plans

In 2013, Esvelt recognized that CRISPR technology could allow scientists to alter the genetics of species for good. This led to the establishment of Mice Against Ticks, an initiative within his lab. For nearly a decade, he and fellow researcher Joanna Buchthal have been investigating whether they could introduce a Lyme-preventing gene into mouse embryos consisting of just two cells. Their method involves injecting both cells to enhance the likelihood of successful genetic integration.

The injection contains both the antibody gene and CRISPR, which acts like tiny scissors to cut the DNA. Once the targeted area is cut, the antibody gene is inserted into the mouse’s genetic makeup. As a result, mice born from this process would be immune to Lyme disease, and that immunity would be passed on to their offspring.

The envisaged strategy involves releasing thousands of engineered mice over time, starting in the winter when the native population is lower. These immune mice wouldn’t pass Lyme onto ticks, thereby slowing the disease’s spread on Nantucket as their population grows.

Weighing the Consequences of Altering Nature

The scientists’ approach essentially accelerates a natural evolutionary process that typically unfolds over thousands or millions of years. “We need to tread carefully because we’re attempting to do things that wouldn’t happen in nature,” Esvelt cautioned.

To proceed, Esvelt must gain community support before releasing the genetically modified mice. Concerns about potential effects on the local ecosystem linger. At town halls, findings have been shared with residents who voice mixed feelings. One individual, who has battled Lyme disease twice, found the plan intriguing but expressed a hint of skepticism, noting that mice are crucial to the food chain.

Sam Telford, an epidemiologist at Tufts University and Esvelt’s collaborator, agrees that poisoning the island’s mice would be simpler and more cost-effective. Yet, he points out the possible repercussions on the local ecosystem, saying, “Tinkering with these mice could disrupt many levels of the food chain.”

Dr. Lepore, who is hesitant to retire yet supportive of the initiative, also seeks assurance about the potential ecological repercussions. Federal and state approvals are needed before any field trials, which may begin on a private island to assess effects before further experiments on Nantucket.

Ultimately, Esvelt shares similar concerns about interfering with nature. “On the other hand, I’m not particularly fond of nature when it’s giving my children diseases,” he remarked. “All technology says to nature, ‘We appreciate your beauty and aim to protect you, but sometimes we’re not content with the natural order. So, we’re going to adjust it.’”