The strong focus on species extinctions, a critical aspect of the contemporary pulse of biological extinction, leads to a common misimpression that Earth’s biota is not immediately threatened, just slowly entering an episode of major biodiversity loss. This view overlooks the current trends of population declines and extinctions.

Understanding the effects of biodiversity loss on zoonotic disease is of pressing importance to both conservation science and public health. This paper provides experimental evidence of increased landscape-level disease risk following declines in large wildlife, using the case study of the rodent-borne zoonosis, bartonellosis, in East Africa. This pattern is driven not by changes in community composition or diversity of hosts, as frequently proposed in other systems, but by increases in abundance of susceptible hosts following large mammal declines.