The 99th Dies Natalis celebration of Wageningen University. The health of people, animals, and their environments are closely connected: think of zoonosis, plant pests or other vector borne diseases. Understanding these interactions is crucial to safeguard the health of people everywhere on the planet. Besides these communicable diseases, a significant impact on public health is caused by global challenges, such as malnutrition, urbanisation and climate change. A Global One Health.