For the past 40 years, Dr. Timothy Lepore has served as the emergency room head, sole surgeon, and medical examiner on Nantucket, a picturesque island located off the coast of Cape Cod, Massachusetts. As he approaches the milestone of retirement at 80 years old, Dr. Lepore continues to manage the only private practice on the island, where he treats dozens of patients suffering from Lyme disease each year. Alarmingly, approximately 15% of Nantucket's residents have been afflicted by this disease, which can lead to a myriad of symptoms including fever, rash, facial paralysis, irregular heartbeat, and arthritis.
Dr. Lepore’s potential retirement may coincide with a groundbreaking initiative by a team of scientists who aim to significantly reduce the transmission of Lyme disease on the island. Rather than targeting the commonly blamed deer or ticks, these researchers are focusing on wild mice—the primary hosts of the Lyme bacteria. Their ambitious plan is to genetically engineer these mice to be immune to Lyme disease and subsequently release them on Nantucket. This strategy hopes to diminish the population of mice capable of spreading the disease.
The Lyme disease issue on Nantucket dates back to 1926, when the community made the decision to import two female deer to provide companionship for a solitary buck. By the 1950s, conservation efforts led to half of the island being protected, which inadvertently created an ideal environment for the hosts of Lyme disease to flourish. As the deer population increased, so did the tick population. Although deer are not affected by Lyme disease, female ticks that feed on them can lay up to 2,000 eggs in a single batch, contributing to the problem. These deer also transport infected ticks across the island, perpetuating the cycle of transmission.
Although not every tick carries Lyme disease, and a bite does not guarantee infection, the risk increases significantly after a tick attaches for more than 24 hours. Furthermore, white-footed mice are recognized as the primary hosts of the Lyme bacteria, playing a crucial role in the disease's transmission cycle.
According to the Centers for Disease Control and Prevention (CDC), Lyme disease affects nearly half a million individuals each year in the United States. While the disease is rarely fatal, it can lead to severe health complications if left untreated. For instance, 33-year-old Shauna Asplint, who was diagnosed with Lyme disease at the age of 10, has experienced lasting effects, including facial paralysis, due to the disease.
In 2013, Kevin Esvelt, a pioneer in genetic engineering and associate professor at MIT, was the first to recognize that CRISPR technology could be utilized to modify the genetics of a species permanently. This discovery led to the formation of the Mice Against Ticks project, spearheaded by Esvelt's Sculpting Evolution lab at MIT. Over the past nine years, he and researcher Joanna Buchthal have been investigating how to introduce a gene for an antibody that prevents Lyme disease into a mouse embryo.
The innovative method involves injecting a mix containing the antibody gene and CRISPR into a two-cell embryo, maximizing the chances of successfully incorporating the gene into the mouse's DNA. Once the engineered mice are born, they would not only be immune to Lyme disease but would also pass this immunity on to their offspring, creating a sustainable solution.
Before releasing genetically engineered mice on Nantucket, Esvelt and his team must secure community approval. Local residents have expressed both interest and caution regarding the potential impacts on the ecosystem. One resident, who has battled Lyme disease twice, acknowledged the innovative approach but raised concerns about the ecological ramifications, stating, "Mice are kind of the foundation of the food chain. So tinkering with the food chain makes me a little cautious."
Despite the complexities, Sam Telford, an epidemiologist at Tufts University and collaborator with Esvelt, recognizes that while it might be easier to poison the mice, such an action could disrupt the entire food chain dependent on these creatures. Dr. Lepore, supportive of the scientists' proposal, seeks further testing to ensure no unintended consequences arise for Nantucket’s ecosystem.
If federal and state regulators grant approval, the researchers plan to initiate a small field trial by releasing the engineered mice on a private island. This trial will help the team assess the ecological impacts before considering any experiments on Nantucket itself. While Esvelt admits to concerns about altering nature, he also emphasizes the necessity of these actions in the context of public health, stating, "I'm not terribly fond of Mother Nature if she's gonna give my kids disease."
In conclusion, the innovative approach to tackling Lyme disease on Nantucket through genetic engineering represents a promising avenue to reduce its prevalence. With the right community support and thorough ecological assessments, this project could potentially pave the way for a healthier future on the island.
