Onesimus: The Enslaved Man Who Saved Boston from Smallpox and Yoruba’s Tradomedical Legacy

Published By Jerry Adesewo On Feb 12, 2025

Onesimus: The Enslaved Man Who Saved Boston from Smallpox and Yoruba’s Tradomedical Legacy

Jerry Adesewo

Every year, on February 13, in the City of Boston, in the United States of America, historians, medical professionals, and advocates of African heritage come together to commemorate Onesimus Day, honouring a man whose knowledge of traditional medicine transformed Western medicine. Onesimus, an enslaved African in 18th-century Boston, played a pivotal role in combating smallpox—a deadly disease that ravaged populations worldwide. Though long overshadowed, his contributions stand as a testament to the wisdom of African traditional medicine, a field that continues to thrive, particularly within Yoruba culture.

Today is another February 13, and as we reflect on Onesimus’ legacy, it becomes clear that his story is not just a singular historical event but part of a broader narrative that connects African medical traditions, particularly Yoruba tradomedical practices, to modern healthcare.

Onesimus and the Battle Against Smallpox

In the early 18th century, smallpox was one of the most feared diseases in the world. The highly contagious virus caused fever, painful rashes, and, in many cases, death. In 1721, Boston was hit with a severe smallpox outbreak that threatened the city’s entire population. During this time, Onesimus, an enslaved man owned by Puritan minister Cotton Mather, shared a remarkable medical knowledge that would change history.

Onesimus told Mather about a practice from his homeland—variolation, a method of inoculation used by many African societies, especially in the Yorubaland of Western Africa. Variolation involves deliberately introducing material from an infected person’s smallpox sores into a healthy individual, usually through a small cut in the skin, otherwise known in Yoruba culture as ‘Gbere’ (incision). While this might result in a mild infection, it granted the recipient immunity against severe smallpox.

This practice had been used for centuries in Yoruba culture, but it was largely unknown in Europe and the American colonies. Mather, recognising the potential of this knowledge, partnered with Dr. Zabdiel Boylston to test the method. Despite widespread skepticism and fierce opposition, they conducted a trial that ultimately proved successful—those who underwent variolation had significantly lower mortality rates than those who did not.

Onesimus’ contribution laid the foundation for modern immunization, influencing the later development of vaccines by Edward Jenner and, eventually, global vaccination programs. Yet, despite the significance of his role, Onesimus remained largely unacknowledged for centuries, his name obscured by history until recent efforts to reclaim his legacy.

The Yoruba Connection: Traditional Medicine and Immunization

Onesimus’ knowledge likely stemmed from West African medical traditions, which share similarities with Yoruba tradomedical practices that persist to this day. Yoruba medicine, known as ‘Oogun’, is an intricate system combining herbal remedies, spiritual healing, and preventative care.

Long before the advent of modern vaccines, Yoruba healers (known as ‘Babalawos’ and ‘Onisegun), employed various forms of immunisation and disease prevention. These methods included the use of herbal infusions, protective charms (‘ẹbọ’ and ‘ase’), and exposure to small doses of illnesses to build resistance—much like the variolation technique Onesimus described.

The Yoruba healing philosophy is holistic, recognising the interconnectedness of the body, spirit, and environment. For example, certain herbs like ‘Dogonyaro’ (neem) and ‘efirin’ (African basil) were used to boost immunity, while divination systems like Ifá guided healers in diagnosing and treating illnesses. This integration of science and spirituality remains a vital part of Yoruba medicine today.

Celebrating Onesimus Day: Honouring African Contributions to Medicine

Thus, February 13 is not just a day to remember Onesimus but an opportunity to celebrate Africa’s broader contributions to medicine. Across the world, historians, scientists, and cultural organizations are working to ensure that figures like Onesimus receive the recognition they deserve.

In Nigeria and the wider Yoruba-speaking world, this commemoration aligns with efforts to preserve and promote traditional medicine. Events on Onesimus Day often include lectures, symposiums, and cultural exhibitions showcasing Yoruba healing practices and their impact on global health.

Moreover, the day serves as a call to action for African governments and institutions to invest in research that bridges traditional medicine with modern healthcare. By supporting herbal medicine research, integrating indigenous healing into national health policies, and educating younger generations about the richness of African medical history, we can ensure that knowledge like Onesimus’, which abounds in every corner of the African continent, continues to benefit future generations.

The Future of African Traditional Medicine

As we move further into the 21st century, the challenge remains: how can Africa reclaim its medical heritage while embracing technological advancements? The key lies in fostering collaboration between traditional healers and biomedical researchers.

Countries like China and India have successfully integrated their traditional medicine systems—Traditional Chinese Medicine (TCM) and Ayurveda—into their national healthcare frameworks. Africa, and especially, Nigeria, can follow suit by creating regulatory bodies that ensure the safe and effective use of traditional remedies, funding clinical trials for herbal medicines, and developing educational programs that respect both indigenous and modern medical knowledge.

In Yoruba culture, there is a saying: ‘Ti a ba fi owo otun we osi, a fi ti osi we otun, Ohun ni owo fi nmo’ (When the right hand washes the left, and the left hand washes the right, both become clean). This proverb highlights the importance of balance and cooperation—precisely what is needed in the integration of traditional and modern medicine.

A Legacy That Lives On

Onesimus’ story is a powerful reminder that history is often written by those in power, while the contributions of marginalised voices are overlooked. By reclaiming his legacy, though belatedly, we acknowledge not only his impact but also the rich medical traditions of Africa that have shaped global healthcare.

As we celebrate Onesimus Day, let us not only honour his role in pioneering immunization but also recognise the countless African healers, scientists, and innovators whose knowledge has safeguarded lives for centuries. Whether through the strengthening of Yoruba tradomedical practices or the continued exploration of indigenous healing systems, Africa has much to offer the world.

The lesson from Onesimus is clear: wisdom transcends borders, and solutions to the world’s greatest challenges can emerge from the most unexpected places—even from an enslaved man who, centuries later, continues to save lives.

One could only hope that, someday, Onesimus would be celebrated in Africa by African leaders, and Yoruba heritage officially confirmed.

Happy Onesimus Day 2025