By Terri McCormick

The Lyme disease community is deeply grateful for the life and work of Dr. Alan B. MacDonald, MD.

Through decades of dedication, curiosity, and persistence, Dr. MacDonald helped advance understanding of Lyme disease and encouraged the medical world to look more closely at what this illness can do to the human body.

Dr. MacDonald was a pathologist, a doctor whose work focused on studying disease at the microscopic level. Beginning in the 1980s, he used his skills to investigate tick-borne illness by examining human tissue directly.

At a time when Lyme disease was still poorly understood and often dismissed, his work helped bring attention to evidence that could only be seen by looking closely at affected tissue.

One of Dr. MacDonald’s most important contributions came from his examination of brain tissue from people diagnosed with Alzheimer’s disease. In some cases, he reported finding structures consistent with Borrelia burgdorferi, the bacterium associated with Lyme disease, including spiral-shaped and round-bodied forms.

His findings raised important questions about whether chronic infection might play a role in neurodegenerative illness for at least some patients and helped open conversations that had not been widely explored before.

Dr. MacDonald believed that studying diseased tissue could reveal information not always captured through blood tests alone. This perspective helped broaden how Lyme disease was studied and discussed, encouraging researchers and clinicians to consider tissue-based evidence alongside traditional testing.

Featured in Under Our Skin

Beyond his work in the laboratory, Dr. MacDonald also helped bring Lyme disease research into the public conversation. He appeared in the documentary Under Our Skin, where he shared his pathology-based findings and helped viewers better understand the complexity of Lyme disease. His participation helped educate patients, families, and clinicians and gave visibility to scientific questions many had never heard discussed before.

Dr. MacDonald was also a connector and educator. In 1987, he organized the Southampton Lyme Symposium, bringing together early leaders in Lyme disease research from many medical specialties. At a time when Lyme disease was still emerging as a recognized illness, this gathering helped highlight its complexity and encouraged collaboration across fields.

Throughout his career, Dr. MacDonald remained committed to asking difficult questions and examining evidence others overlooked. His lectures, presentations, and published work continue to educate researchers, clinicians, and patients, and his influence is still felt within the Lyme disease community today.

In recognition of his contributions, Dr. MacDonald was honored with the Pioneer in Lyme Disease Award by the International Lyme and Associated Diseases Society in 2015. The award acknowledged his decades of pathology-based research and his willingness to pursue difficult questions that helped advance understanding of Lyme disease.

We are deeply grateful for Dr. MacDonald’s dedication, courage, and willingness to look deeper. His work helped move the needle in how Lyme disease is understood, and his contributions have left a lasting mark on research, education, and advocacy.

Our thoughts are with Dr. MacDonald’s family, friends, colleagues, and all those who were touched by his life and work. We hope they find comfort in knowing how meaningful his contributions have been to so many.

Terri McCormick is a writer and advocate with LymeDisease.org. She has several family members with Lyme disease, has facilitated a patient support group, and is author of the forthcoming book Being Misdiagnosed: Stories That Reveal the Hidden Epidemic of Lyme Disease.